Slim Holes At Blue Mountain Geothermal Area (Fairbank Engineering...
Home Exploration Activity: Slim Holes At Blue Mountain Geothermal Area (Fairbank Engineering Ltd, 2003) Exploration Activity Details Location Blue Mountain Geothermal Area...
Slim Holes At Maui Area (DOE GTP) | Open Energy Information
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Slim Holes At Fort Bliss Area (DOE GTP) | Open Energy Information
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Slim Holes At Gabbs Valley Area (DOE GTP) | Open Energy Information
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Slim Holes At Glass Buttes Area (DOE GTP) | Open Energy Information
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New bits, motors improve economics of slim hole horizontal wells
McDonald, S. [Hughes Christensen Co., New Orleans, LA (United States); Felderhoff, F. [Hughes Christensen Co., Midland, TX (United States); Fisher, K. [Baker Hughes Inteq, New Orleans, LA (United States)
1996-03-11T23:59:59.000Z
The latest generation of small-diameter bits, combined with a new extended power section positive displacement motor (PDM), has improved the economics of slim hole drilling programs. As costs are driven down, redevelopment reserves are generated in the older, more established fields. New reserves result from increases in the ultimate recovery and accelerated production rates from the implementation of horizontal wells in reentry programs. This logic stimulated an entire development program for a Gulf of Mexico platform, which was performed without significant compromises in well bore geometry. The savings from this new-generation drilling system come from reducing the total number of trips required during the drilling phase. This paper reviews the design improvements of roller cone bits, PDC bits, and positive displacement motors for offshore directional drilling operations.
Slim Holes At Fish Lake Valley Area (Deymonaz, Et Al., 2008) | Open Energy
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Slim Holes At Flint Geothermal Area (DOE GTP) | Open Energy Information
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Slim Holes At Fort Bliss Area (Combs, Et Al., 1999) | Open Energy
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Slim Holes At Hot Pot Area (DOE GTP) | Open Energy Information
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Slim Holes At International Geothermal Area, Japan (Combs, Et Al., 1999) |
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Slim Holes At Jemez Pueblo Area (DOE GTP) | Open Energy Information
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Slim Holes At New River Area (DOE GTP) | Open Energy Information
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Slim Holes At Newberry Caldera Area (Combs, Et Al., 1999) | Open Energy
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Slim Holes At Newberry Caldera Area (DOE GTP) | Open Energy Information
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Slim Holes At Reese River Area (Henkle & Ronne, 2008) | Open Energy
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Slim Holes At Silver Peak Area (DOE GTP) | Open Energy Information
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Slim Holes At Snake River Plain Region (DOE GTP) | Open Energy Information
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Slim Holes At Steamboat Springs Area (Combs, Et Al., 1999) | Open Energy
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Slim Holes At Steamboat Springs Area (Warpinski, Et Al., 2002) | Open
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Slim Holes At Steamboat Springs Area (Warpinski, Et Al., 2004) | Open
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Phase 2 and 3 Slim Hole Drilling and Testing at the Lake City, California Geothermal Field
Dick Benoit; David Blackwell; Joe Moore; Colin Goranson
2005-10-27T23:59:59.000Z
During Phases 2 and 3 of the Lake City GRED II project two slim holes were cored to depths of 1728 and 4727 ft. Injection and production tests with temperature and pressure logging were performed on the OH-1 and LCSH-5 core holes. OH-1 was permanently modified by cementing an NQ tubing string in place below a depth of 947 ft. The LCSH-1a hole was drilled in Quaternary blue clay to a depth of 1727 ft and reached a temperature of 193 oF at a depth of 1649 ft. This hole failed to find evidence of a shallow geothermal system east of the Mud Volcano but the conductive temperature profile indicates temperatures near 325 oF could be present below depth of 4000 ft. The LCSH-5 hole was drilled to a depth of 4727 ft and encountered a significant shallow permeability between depths of 1443 and 1923 ft and below 3955 ft. LCSH-5 drilled impermeable Quaternary fanglomerate to a depth of 1270 ft. Below 1270 ft the rocks consist primarily of Tertiary sedimentary rocks. The most significant formation deep in LCSH-5 appears to be a series of poikoilitic mafic lava flows below a depth of 4244 ft that host the major deep permeable fracture encountered. The maximum static temperature deep in LCSH-5 is 323 oF and the maximum flowing temperature is 329 oF. This hole extended the known length of the geothermal system by ¾ of a mile toward the north and is located over ½ mile north of the northernmost hot spring. The OH-1 hole was briefly flow tested prior to cementing the NQ rods in place. This flow test confirmed the zone at 947 ft is the dominant permeability in the hole. The waters produced during testing of OH-1 and LCSH-5 are generally intermediate in character between the deep geothermal water produced by the Phipps #2 well and the thermal springs. Geothermometers applied to deeper fluids tend to predict higher subsurface temperatures with the maximum being 382 oF from the Phipps #2 well. The Lake City geothermal system can be viewed as having shallow (elevation > 4000 ft and temperatures of 270 to 310 oF), intermediate (elevation 2800 to 3700 ft and temperatures 270 to 320 oF ) and deep (elevations < 1000 ft and temperatures 323 to 337 oF) components. In the south part of the field, near Phipps #2 the shallow and deep components are present. In the central part of the field, near OH-1 the shallow and intermediate components are present and presumably the deep component is also present. In the north part of the field, the intermediate and deep components are present. Most or all of the fractures in the core have dips between 45 degrees and vertical and no strong stratigraphic control on the resource has yet been demonstrated. Conceptually, the Lake City geothermal resource seems to be located along the north-south trending range front in a relatively wide zone of fractured rock. The individual fractures do not seem to be associated with any readily identifiable fault. In fact, no major hydraulically conductive faults were identified by the core drilling.
SLIM, Short-pulse Technology for High Gradient Induction Accelerators
Krasnykh, A.; /SLAC; Kardo-Sysoev, A.; /Ioffe Phys. Tech. Inst.; Arntz, F.; /Diversified Tech., Bedford
2009-12-09T23:59:59.000Z
The conclusions of this paper are: (1) The gradient of the SLIM-based technology is believed to be achievable in the same range as it is for the gradient of a modern rf-linac technology ({approx}100 MeV per meter). (2) The SLIM concept is based on the nsec TEM pulse mode operation with no laser or rf systems. (3) Main components of SLIM are not stressed while the energy is pumped into the induction system. Components can accept the hard environment conditions such as a radiation dose, mismatch, hard electromagnetic nose level, etc. Only for several nanoseconds the switch is OFF and produces a stress in the induction system. At that time, the delivery of energy to the beam takes place. (4) The energy in the induction system initially is storied in the magnetic field when the switch is ON. That fact makes another benefit: a low voltage power supplies can be used. The reliability of a lower voltage power supply is higher and they are cheaper. (5) The coreless SLIM concept offers to work in the MHz range of repetition rate. The induction system has the high electric efficiency (much higher than the DWA). (6) The array of lined up and activated SLIM cells is believed to be a solid state structure of novel accelerating technology. The electron-hole plasma in the high power solid state structure is precisely controlled by the electromagnetic process of a pulsed power supply.
Slim Holes | Open Energy Information
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Category:Slim Holes | Open Energy Information
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SLIM, Short-pulse Technology for High Gradient Induction Accelerators
Arntz, Floyd; /Diversified Tech., Bedford; Kardo-Sysoev, A.; /Ioffe Phys. Tech. Inst.; Krasnykh, A.; /SLAC
2008-12-16T23:59:59.000Z
A novel short-pulse concept (SLIM) suited to a new generation of a high gradient induction particle accelerators is described herein. It applies advanced solid state semiconductor technology and modern microfabrication techniques to a coreless induction method of charged particle acceleration first proven on a macro scale in the 1960's. Because this approach avoids use of magnetic materials there is the prospect of such an accelerator working efficiently with accelerating pulses in the nanosecond range and, potentially, at megahertz pulse rates. The principal accelerator section is envisioned as a stack of coreless induction cells, the only active element within each being a single, extremely fast (subnanosecond) solid state opening switch: a Drift Step Recovery Diode (DSRD). Each coreless induction cell incorporates an electromagnetic pulse compressor in which inductive energy developed within a transmission-line feed structure over a period of tens of nanoseconds is diverted to the acceleration of the passing charge packet for a few nanoseconds by the abrupt opening of the DSRD switch. The duration of this accelerating output pulse--typically two-to-four nanoseconds--is precisely determined by a microfabricated pulse forming line connected to the cell. Because the accelerating pulse is only nanoseconds in duration, longitudinal accelerating gradients approaching 100 MeV per meter are believed to be achievable without inciting breakdown. Further benefits of this approach are that, (1) only a low voltage power supply is required to produce the high accelerating gradient, and, (2) since the DSRD switch is normally closed, voltage stress is limited to a few nanoseconds per period, hence the susceptibility to hostile environment conditions such as ionizing radiation, mismatch (e.g. in medical applications the peak beam current may be low), strong electromagnetic noise levels, etc is expected to be minimal. Finally, we observe the SLIM concept is not limited to linac applications; for instance, it could be employed to both accelerate the beam and to stabilize the superbunch mode of operation in circular track machines.
Spin orientation of supermassive black holes in active galaxies
W. Kollatschny
2003-11-12T23:59:59.000Z
Accretion of gas onto a central supermassive black hole is generally accepted to be the source of the emitted energy in active galactic nuclei.The broad emission lines we observe in their optical spectra are probably formed in the wind of an accretion disk at distances of light days to light years from the central black hole. The variable fraction of the emission lines originates at typical distances of only 1 to 50 light days from the central supermassive black hole. We derived a central black hole mass of M_orbital = 1.8 +/-0.4 x 10^7 M_sun in the Seyfert galaxy Mrk110 assuming the broad emission lines are generated in gas clouds orbiting within an accretion disk. This figure depends on the inclination angle of the accretion disk. Here we report on the detection of gravitational redshifted emission in the variable fraction of the broad emission lines. We derive a central black hole mass of M_grav = 14.0 +/-3.0 x 10^7 M_sun. These measurements are independent on the orientation of the accretion disk. The comparison of both black hole mass estimates allows to determine the projection of the central accretion disk angle i to 21 +/-5 deg. in Mrk110 and therefore the orientation of the spin axis of the central black hole.
Slim Holes At Blue Mountain Geothermal Area (Fairbank Engineering Ltd,
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Slim Holes At Alum Area (DOE GTP) | Open Energy Information
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The Fundamental Plane of Black Hole Activity in the Optical Band
Saikia, Payaswini; Falcke, Heino
2015-01-01T23:59:59.000Z
Black hole accretion and jet formation have long been thought to be scale invariant. One empirical relation suggesting scale invariance is the Fundamental Plane of Black Hole activity, which is a plane in the space given by black hole mass and the radio/X-ray luminosities. We search for an alternative version of this plane using the luminosity of [OIII] emission line instead of X-ray luminosity. We use a complete sample of 39 supermassive black holes selected from the Palomar Spectroscopic Survey with available radio and optical measurements and information on black hole mass. A sample of stellar mass X-ray binaries has also been included to examine if physical processes behind accretion is universal across the entire range of black hole mass. We present the results of multivariate regression analysis performed on the AGN sample and show that the sample stretches out as a plane in the 3D logarithmic space created by bolometric luminosity, radio luminosity and black hole mass. We reproduce the established Fund...
Lasota, Jean-Pierre
2015-01-01T23:59:59.000Z
This is an introduction to models of accretion discs around black holes. After a presentation of the non-relativistic equations describing the structure and evolution of geometrically thin accretion discs we discuss their steady-state solutions and compare them to observation. Next we describe in detail the thermal-viscous disc instability model and its application to dwarf novae for which it was designed and its X-ray irradiated-disc version which explains the soft X--ray transients, i.e. outbursting black-hole low-mass X-ray binaries. We then turn to the role of advection in accretion flow onto black holes illustrating its action and importance with a toy model describing both ADAFs and slim discs. We conclude with a presentation of the general-relativistic formalism describing accretion discs in the Kerr space-time.
Radio Jets in Galaxies with Actively Accreting Black Holes: new insights from the SDSS
Guinevere Kauffmann; Timothy M. Heckman; Philip N. Best
2007-09-19T23:59:59.000Z
The majority of nearby radio-loud AGN are found in massive, old elliptical galaxies with weak emission lines. At high redshifts,however, most known radio AGN have strong emission lines. In this paper, we examine a subset of radio AGN with emission lines selected from the Sloan Digital Sky Survey. The probability for a nearby radio AGN to have emission lines is a strongly decreasing function of galaxy mass and an increasing function of radio luminosity above 10^25 W/Hz. Emission line and radio luminosities are correlated, but with large dispersion. At a given radio power, AGN with small black holes have higher [OIII] luminosities (which we interpret as higher accretion rates) than AGN with big black holes. However, if we scale both radio and emission line luminosities by the black hole mass, we find a correlation between normalized radio power and accretion rate in Eddington units that is independent of black hole mass. There is also a clear correlation between normalized radio power and the age of the stellar population in the galaxy. Present-day AGN with the highest normalized radio powers are confined to galaxies with small black holes. High-redshift, high radio-luminosity AGN could be explained if big black holes were similarly active at earlier cosmic epochs. To investigate why only a small fraction of emission line AGN become radio loud, we create matched samples of radio-loud and radio-quiet AGN and compare their host galaxy properties and environments. The main difference lies in their environments; our local density estimates are a factor 2 larger around the radio-loud AGN. We propose a scenario in which radio-loud AGN with emission lines are located in galaxies where accretion of both cold and hot gas can occur simultaneously. (Abridged)
A MONTE CARLO MARKOV CHAIN BASED INVESTIGATION OF BLACK HOLE SPIN IN THE ACTIVE GALAXY NGC 3783
Reynolds, Christopher S.
The analysis of relativistically broadened X-ray spectral features from the inner accretion disk provides a powerful tool for measuring the spin of supermassive black holes in active galactic nuclei (AGNs). However, AGN ...
Phase 2 Reese River Geothermal Project Slim Well 56-4 Drilling and Testing
Henkle, William R.; Ronne, Joel
2008-06-15T23:59:59.000Z
This report covers the drilling and testing of the slim well 56-4 at the Reese River Geothermal Project in Lander County, Nevada. This well was partially funded through a GRED III Cooperative Funding Agreement # DE-FC36-04GO14344, from USDOE.
Slim Holes At Alvord Hot Springs Area (Combs, Et Al., 1999) | Open Energy
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Slim Holes At Hawthorne Area (Sabin, Et Al., 2010) | Open Energy
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Slim Holes At Salt Wells Area (Combs, Et Al., 1999) | Open Energy
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Slim Holes At Salton Sea Area (Sabin, Et Al., 2010) | Open Energy
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Slim Holes At Vale Hot Springs Area (Combs, Et Al., 1999) | Open Energy
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Slim Holes At Black Warrior Area (DOE GTP) | Open Energy Information
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Slim Holes At Blue Mountain Area (Warpinski, Et Al., 2002) | Open Energy
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Slim Holes At Crump's Hot Springs Area (DOE GTP) | Open Energy Information
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The cosmic growth of the active black hole population at 1
Schulze, A; Gavignaud, I; Schramm, M; Silverman, J; Merloni, A; Zamorani, G; Hirschmann, M; Mainieri, V; Wisotzki, L; Shankar, F; Fiore, F; Koekemoer, A M; Temporin, G
2014-01-01T23:59:59.000Z
We present a census of the active black hole population at 1
Garimella, Venkata BS; Ibrahim, Yehia M.; Webb, Ian K.; Tolmachev, Aleksey V.; Zhang, Xinyu; Prost, Spencer A.; Anderson, Gordon A.; Smith, Richard D.
2014-11-01T23:59:59.000Z
We report a conceptual study and computational evaluation of novel planar electrode Structures for Lossless Ion Manipulations (SLIM). Planar electrode SLIM devices were designed that allow for flexible ion confinement, transport and storage using a combination of RF and DC fields. Effective potentials can be generated that provide near ideal regions for confining ions in the presence of a gas. Ion trajectory simulations using SIMION 8.1 demonstrated the capability for lossless ion motion in these devices over a wide m/z range and a range of electric fields at low pressures (e.g. a few torr). More complex ion manipulations, e.g. turning ions by 90o and dynamically switching selected ion species into orthogonal channels, are also feasible. The performance of SLIM devices at ~4 torr pressure for performing ion mobility based separations (IMS) is computationally evaluated and compared to initial experimental results, and both of which agree closely with experimental and theoretical IMS performance for a conventional drift tube design.
On The Linearity of The Black Hole - Bulge Mass Relation in Active and in Nearby Galaxies
Ari Laor
2001-01-23T23:59:59.000Z
Analysis of PG quasar observations suggests a nonlinear relation between the black hole mass, M_BH, and the bulge mass, M_bulge, although a linear relation, as proposed for nearby galaxies, cannot be ruled out. New M_BH values for nearby galaxies from Gebhardt et al., and L_bulge measurements for Seyfert 1 galaxies from Virani et al., are used here to obtain a more accurate value for the slope of the M_BH-M_bulge relation. The combined sample of 40 active and non-active galaxies suggests a significantly nonlinear relation, M_BH\\propto M_bulge^{1.53\\pm 0.14}. Further support for a nonlinear relation is provided by the slope of the M_BH-stellar velocity dispersion relation found recently, and by the low M_BH found in late type spiral galaxies. The mean M_BH/M_bulge ratio is therefore not a universal constant, but rather drops from ~0.5% in bright (M_V ~ -22) ellipticals, to ~0.05% in low luminosity (M_V ~ -18) bulges. Hubble Space Telescope determinations of M_BH in late type spirals, and of the bulge magnitude in narrow line Seyfert 1 galaxies (both predicted to have low M_BH), can further test the validity of the nonlinear M_BH-M_bulge relation.
Energy input from quasars regulates the growth and activity of black holes and their host galaxies
Tiziana Di Matteo; Volker Springel; Lars Hernquist
2005-02-09T23:59:59.000Z
In the early Universe, while galaxies were still forming, black holes as massive as a billion solar masses powered quasars. Supermassive black holes are found at the centers of most galaxies today, where their masses are related to the velocity dispersions of stars in their host galaxies and hence to the mass of the central bulge of the galaxy. This suggests a link between the growth of the black holes and the host galaxies, which has indeed been assumed for a number of years. But the origin of the observed relation between black hole mass and stellar velocity dispersion, and its connection with the evolution of galaxies have remained unclear. Here we report simulations that simultaneously follow star formation and the growth of black holes during galaxy-galaxy collisions. We find that in addition to generating a burst of star formation, a merger leads to strong inflows that feed gas to the supermassive black hole and thereby power the quasar. The energy released by the quasar expels enough gas to quench both star formation and further black hole growth. This determines the lifetime of the quasar phase (approaching 100 million years) and explains the relationship between the black hole mass and the stellar velocity dispersion.
Roberto Soria; Alister W. Graham; Giuseppina Fabbiano; Alessandro Baldi; Martin Elvis; Helmut Jerjen; Silvia Pellegrini; Aneta Siemiginowska
2005-11-11T23:59:59.000Z
Our X-ray study of the nuclear activity in a new sample of six quiescent early-type galaxies, and in a larger sample from the literature, confirmed (Soria et al., Paper I) that the Bondi accretion rate of diffuse hot gas is not a good indicator of the supermassive black hole (SMBH) X-ray luminosity. Here we suggest that a more reliable estimate of the accretion rate must include the gas released by the stellar population inside the sphere of influence of the SMBH, in addition to the Bondi inflow of hot gas across that surface. We use optical surface-brightness profiles to estimate the mass-loss rate from stars in the nuclear region: we show that for our sample of galaxies it is an order of magnitude higher (~ 10^{-4} - 10^{-3} M_sun/yr) than the Bondi inflow rate of hot gas, as estimated from Chandra (Paper I). Only by taking into account both sources of fuel can we constrain the true accretion rate, the accretion efficiency, and the power budget. Radiatively efficient accretion is ruled out, for quiescent SMBHs. For typical radiatively inefficient flows, the observed X-ray luminosities of the SMBHs imply accretion fractions ~ 1 - 10% (ie, ~ 90 - 99% of the available gas does not reach the SMBH) for at least five of our six target galaxies, and most of the other galaxies with known SMBH masses. We discuss the conditions for mass conservation inside the sphere of influence, so that the total gas injection is balanced by accretion plus outflows. We show that a fraction of the total accretion power (mechanical plus radiative) would be sufficient to sustain a self-regulating, slow outflow which removes from the nuclear region all the gas that does not sink into the BH (``BH feedback''). The rest of the accretion power may be carried out in a jet, or advected. We also discuss scenarios that would lead to an intermittent nuclear activity.
Park, Daeseong; Bennert, Vardha N; Treu, Tommaso; Auger, Matthew W; Malkan, Matthew A
2014-01-01T23:59:59.000Z
We investigate the cosmic evolution of the black hole (BH) mass -- bulge luminosity relation using a sample of 52 active galaxies at $z \\sim 0.36$ and $z \\sim 0.57$ in the BH mass range of $10^{7.4-9.1} M_{\\odot}$. By consistently applying multi-component spectral and structural decomposition to high-quality Keck spectra and high-resolution HST images, BH masses ($M_{\\rm BH}$) are estimated using the H$\\beta$ broad emission line combined with the 5100 \\AA\\ nuclear luminosity, and bulge luminosities ($L_{\\rm bul}$) are derived from surface photometry. Comparing the resulting $M_{\\rm BH}-L_{\\rm bul}$ relation to local active galaxies and taking into account selection effects, we find evolution of the form $M_{\\rm BH} / L_{\\rm bul} \\propto (1+z)^{\\gamma}$ with $\\gamma=1.8\\pm0.7$, consistent with BH growth preceding that of the host galaxies. Including an additional sample of 27 active galaxies with $0.5
Accretion and nuclear activity of quiescent supermassive black holes. I: X-ray study
Roberto Soria; Giuseppina Fabbiano; Alister W. Graham; Alessandro Baldi; Martin Elvis; Helmut Jerjen; Silvia Pellegrini; Aneta Siemiginowska
2005-11-10T23:59:59.000Z
We have studied the nuclear activity in a sample of six quiescent early-type galaxies, with new Chandra data and archival HST optical images. Their nuclear sources have X-ray luminosities ~ 10^{38} - 10^{39} erg/s (L_X/L_Edd ~ 10^{-8} - 10^{-7}), and colors or spectra consistent with accreting supermassive black holes (SMBHs)--except for the nucleus of NGC 4486B, which is softer than typical AGN spectra. In a few cases, the X-ray morphology of the nuclear sources shows hints of marginally extended structures, in addition to the surrounding diffuse thermal emission from hot gas, which is detectable on scales >~ 1 kpc. In one case (NGC 5845), a dusty disk may partially obstruct our direct view of the SMBH. We have estimated the temperature and density of the hot interstellar medium, which is one major source of fuel for the accreting SMBH; typical central densities are n_e ~ (0.02 +/- 0.01) cm^{-3}. Assuming that the hot gas is captured by the SMBH at the Bondi rate, we show that the observed X-ray luminosities are too faint to be consistent with standard disk accretion, but brighter than predicted by radiatively-inefficient solutions (eg, ADAF). In total, there are ~ 20 galaxies for which SMBH mass, hot gas density, and nuclear X-ray luminosity are simultaneously known. In some cases, the nuclear sources are brighter than predicted by the ADAF model; in other cases, they are consistent or fainter. We discuss the apparent lack of correlations between Bondi rate and X-ray luminosity, and suggest that, in order to understand the observed distribution, we need to know two additional parameters: the amount of gas supplied by the stellar population inside the accretion radius, and the fraction (possibly << 1) of the total gas available that is accreted by the SMBH. We shall discuss these issues in our Paper II.
Brandt, W N
2015-01-01T23:59:59.000Z
We review results from cosmic X-ray surveys of active galactic nuclei (AGNs) over the past ~ 15 yr that have dramatically improved our understanding of growing supermassive black holes (SMBHs) in the distant universe. First, we discuss the utility of such surveys for AGN investigations and the capabilities of the missions making these surveys, emphasizing Chandra, XMM-Newton, and NuSTAR. Second, we briefly describe the main cosmic X-ray surveys, the essential roles of complementary multiwavelength data, and how AGNs are selected from these surveys. We then review key results from these surveys on the AGN population and its evolution ("demographics"), the physical processes operating in AGNs ("physics"), and the interactions between AGNs and their environments ("ecology"). We conclude by describing some significant unresolved questions and prospects for advancing the field.
Casanova, David, E-mail: david.casanova@ehu.es [Kimika Fakultatea, Euskal Herria Unibersitatea (UPV/EHU), Donostia International Physics Center (DIPC), P.K. 1072, 20080 Donostia, Spain and IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain)] [Kimika Fakultatea, Euskal Herria Unibersitatea (UPV/EHU), Donostia International Physics Center (DIPC), P.K. 1072, 20080 Donostia, Spain and IKERBASQUE, Basque Foundation for Science, 48011 Bilbao (Spain)
2014-04-14T23:59:59.000Z
Second-order corrections to the restricted active space configuration interaction (RASCI) with the hole and particle truncation of the excitation operator are developed. Theoretically, the computational cost of the implemented perturbative approach, abbreviated as RASCI(2), grows like its single reference counterpart in MP2. Two different forms of RASCI(2) have been explored, that is the generalized Davidson-Kapuy and the Epstein-Nesbet partitions of the Hamiltonian. The preliminary results indicate that the use of energy level shift of a few tenths of a Hartree might systematically improve the accuracy of the RASCI(2) energies. The method has been tested in the computation of the ground state energy profiles along the dissociation of the hydrogen fluoride and N{sub 2} molecules, the computation of correlation energy in the G2/97 molecular test set, and in the computation of excitation energies to low-lying states in small organic molecules.
Cranmer, Steven R
2009-01-01T23:59:59.000Z
Coronal holes are the darkest and least active regions of the Sun, as observed both on the solar disk and above the solar limb. Coronal holes are associated with rapidly expanding open magnetic fields and the acceleration of the high-speed solar wind. This paper reviews measurements of the plasma properties in coronal holes and how these measurements are used to reveal details about the physical processes that heat the solar corona and accelerate the solar wind. It is still unknown to what extent the solar wind is fed by flux tubes that remain open (and are energized by footpoint-driven wave-like fluctuations), and to what extent much of the mass and energy is input intermittently from closed loops into the open-field regions. Evidence for both paradigms is summarized in this paper. Special emphasis is also given to spectroscopic and coronagraphic measurements that allow the highly dynamic non-equilibrium evolution of the plasma to be followed as the asymptotic conditions in interplanetary space are establish...
Identification of the Active Species in Photochemical Hole Scavenging Reactions of Methanol on TiO2
Shen, Mingmin; Henderson, Michael A.
2011-11-03T23:59:59.000Z
Molecular and dissociative methanol adsorption species were prepared on rutile TiO2(110) surfaces to study photocatalytic oxidation of methanol in ultrahigh vacuum (UHV) using temperature-programmed desorption (TPD). Adsorbed methoxy groups (CH3O-) were found to be the photoactive form of adsorbed methanol converted to adsorbed formaldehyde and a surface OH group by hole-mediated C-H bond cleavage. These results suggest that adsorbed methoxy is the effective hole scavenger in photochemical reactions involving methanol.
P. K. Townsend
1997-07-04T23:59:59.000Z
Lecture notes for a 'Part III' course 'Black Holes' given in DAMTP, Cambridge. The course covers some of the developments in Black Hole physics of the 1960s and 1970s.
Black Warrior: Sub-soil gas and fluid inclusion exploration and slim well drilling
Broader source: Energy.gov [DOE]
DOE Geothermal Peer Review 2010 - Presentation. Project Objectives: Discover a blind, low-moderate temperature resource: Apply a combination of detailed sub-soil gas, hydrocarbon, and isotope data to define possible upflow areas; Calibrate the sub-soil chemistry with down-hole fluid inclusion stratigraphy and fluid analyses to define a follow-up exploration drilling target; Create short term jobs and long term employment through resource exploration, development and power plant operation; Extend and adapt the DOE sub-soil 2 meter probe technology to gas sampling.
BLACK HOLE AURORA POWERED BY A ROTATING BLACK HOLE
Takahashi, Masaaki [Department of Physics and Astronomy, Aichi University of Education, Kariya, Aichi 448-8542 (Japan); Takahashi, Rohta, E-mail: takahasi@phyas.aichi-edu.ac.j [Cosmic Radiation Laboratory, Institute of Physical and Chemical Research, 2-1 Hirosawa, Wako, Saitama 351-0198 (Japan)
2010-05-15T23:59:59.000Z
We present a model for high-energy emission sources generated by a standing magnetohydrodynamical (MHD) shock in a black hole magnetosphere. The black hole magnetosphere would be constructed around a black hole with an accretion disk, where a global magnetic field could be originated by currents in the accretion disk and its corona. Such a black hole magnetosphere may be considered as a model for the central engine of active galactic nuclei, some compact X-ray sources, and gamma-ray bursts. The energy sources of the emission from the magnetosphere are the gravitational and electromagnetic energies of magnetized accreting matters and the rotational energy of a rotating black hole. When the MHD shock generates in MHD accretion flows onto the black hole, the plasma's kinetic energy and the black hole's rotational energy can convert to radiative energy. In this Letter, we demonstrate the huge energy output at the shock front by showing negative energy postshock accreting MHD flows for a rapidly rotating black hole. This means that the extracted energy from the black hole can convert to the radiative energy at the MHD shock front. When an axisymmetric shock front is formed, we expect a ring-shaped region with very hot plasma near the black hole; this would look like an 'aurora'. The high-energy radiation generated from there would carry to us the information for the curved spacetime due to the strong gravity.
Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank...
search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank & Ross, 1999) Exploration Activity Details Location...
Thermal Gradient Holes At Blue Mountain Geothermal Area (Fairbank...
Blue Mountain Geothermal Area (Fairbank & Niggemann, 2004) Exploration Activity Details Location Blue Mountain Geothermal Area Exploration Technique Thermal Gradient Holes Activity...
Thermal Gradient Holes At Long Valley Caldera Geothermal Area...
Geothermal Area (Farrar, Et Al., 2003) Exploration Activity Details Location Long Valley Caldera Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1998 -...
Thermal Gradient Holes At Long Valley Caldera Geothermal Area...
Activity Details Location Long Valley Caldera Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1991 - 1991 Usefulness not useful DOE-funding Unknown...
Thermal Gradient Holes At Long Valley Caldera Geothermal Area...
Activity Details Location Long Valley Caldera Geothermal Area Exploration Technique Thermal Gradient Holes Activity Date 1978 - 1985 Usefulness useful DOE-funding Unknown...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Black Holes at RHIC? Further discussion by Physicist Dmitri Kharzeev on why RHIC cannot produce a real gravitational black hole Black holes are among the most mysterious objects in...
Thermal Gradient Holes At Waunita Hot Springs Geothermal Area...
Zacharakis, 1981) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Waunita Hot Springs Geothermal Area (Zacharakis,...
Thermal Gradient Holes At Lightning Dock Geothermal Area (Cunniff...
Thermal Gradient Holes At Lightning Dock Geothermal Area (Cunniff & Bowers, 2005) Exploration Activity Details Location Lightning Dock Geothermal Area Exploration Technique Thermal...
Thermal Gradient Holes At North Brawley Geothermal Area (Matlick...
Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At North Brawley Geothermal Area (Matlick & Jayne, 2008) Exploration...
Stanford University
geochemical and geophysical surveys as well as drilling temperature gradient holes (Sudarman et al, 1986 at Wayang Windu including 17 active production wells, two active reinjection wells and five slim holes and boundary conditions were defined based on available data from the drilled area. The distribution
Optoelectronic device with nanoparticle embedded hole injection/transport layer
Wang, Qingwu (Chelmsford, MA); Li, Wenguang (Andover, MA); Jiang, Hua (Methuen, MA)
2012-01-03T23:59:59.000Z
An optoelectronic device is disclosed that can function as an emitter of optical radiation, such as a light-emitting diode (LED), or as a photovoltaic (PV) device that can be used to convert optical radiation into electrical current, such as a photovoltaic solar cell. The optoelectronic device comprises an anode, a hole injection/transport layer, an active layer, and a cathode, where the hole injection/transport layer includes transparent conductive nanoparticles in a hole transport material.
Sean A. Hayward
2009-02-28T23:59:59.000Z
This is a review of current theory of black-hole dynamics, concentrating on the framework in terms of trapping horizons. Summaries are given of the history, the classical theory of black holes, the defining ideas of dynamical black holes, the basic laws, conservation laws for energy and angular momentum, other physical quantities and the limit of local equilibrium. Some new material concerns how processes such as black-hole evaporation and coalescence might be described by a single trapping horizon which manifests temporally as separate horizons.
B. Kleihaus; J. Kunz
2000-12-20T23:59:59.000Z
We construct stationary black holes in SU(2) Einstein-Yang-Mills theory, which carry angular momentum and electric charge. Possessing non-trivial non-abelian magnetic fields outside their regular event horizon, they represent non-perturbative rotating hairy black holes.
Disregarding the 'Hole Argument'
Bryan W. Roberts
2014-12-17T23:59:59.000Z
Jim Weatherall has suggested that Einstein's hole argument, as presented by Earman and Norton (1987), is based on a misleading use of mathematics. I argue on the contrary that Weatherall demands an implausible restriction on how mathematics is used. The hole argument, on the other hand, is in no new danger at all.
El Paso County Geothermal Project at Fort Bliss
Broader source: Energy.gov (indexed) [DOE]
GIS database development * Conceptual geologicgeothermal system modeling - Slim-hole drilling & Resource testing * Corecuttings analysis including XRD * Integrated wellbore...
Authors, Various
2011-01-01T23:59:59.000Z
drilling techniques and fluids should be optimized to decrease disturbance and contaminationJ slim-hole
On Noncommutative Black Holes Thermodynamics
Faizal, Mir; Ulhoa, S C
2015-01-01T23:59:59.000Z
In this paper, we will analyze noncommutative deformation of the Schwarzschild black holes and Kerr black holes. We will perform our analysis by relating the commutative and the noncommutative metrics using an Moyal product. We will also analyze the thermodynamics of these noncommutative black hole solutions. We will explicitly derive expression for the corrected entropy and temperature of these black hole solutions.
Fontana, Peter R.; Srivastava, Rajendra P.
1973-06-01T23:59:59.000Z
The decay of an atom in the presence of a static perturbation is investigated. The perturbation couples a decaying state with a nondecaying state. A "hole" appears in the emission line at a frequency equal to the frequency difference between...
J. W. Moffat
1993-02-22T23:59:59.000Z
The problem of information loss in black hole formation and the associated violations of basic laws of physics, such as conservation of energy, causality and unitarity, are avoided in the nonsymmetric gravitational theory, if the NGT charge of a black hole and its mass satisfy an inequality that does not violate any known experimental data and allows the existence of white dwarfs and neutron stars.
Helical superconducting black holes
Aristomenis Donos; Jerome P. Gauntlett
2012-05-17T23:59:59.000Z
We construct novel static, asymptotically $AdS_5$ black hole solutions with Bianchi VII$_0$ symmetry that are holographically dual to superconducting phases in four spacetime dimensions with a helical p-wave order. We calculate the precise temperature dependence of the pitch of the helical order. At zero temperature the black holes have vanishing entropy and approach domain wall solutions that reveal homogenous, non-isotropic dual ground states with emergent scaling symmetry.
Thermal Gradient Holes At Salt Wells Area (Bureau of Land Management...
Salt Wells Area (Bureau of Land Management, 2009) Jump to: navigation, search GEOTHERMAL ENERGYGeothermal Home Exploration Activity: Thermal Gradient Holes At Salt Wells Area...
Gravitating discs around black holes
V. Karas; J. -M. Hure; O. Semerak
2004-01-16T23:59:59.000Z
Fluid discs and tori around black holes are discussed within different approaches and with the emphasis on the role of disc gravity. First reviewed are the prospects of investigating the gravitational field of a black hole--disc system by analytical solutions of stationary, axially symmetric Einstein's equations. Then, more detailed considerations are focused to middle and outer parts of extended disc-like configurations where relativistic effects are small and the Newtonian description is adequate. Within general relativity, only a static case has been analysed in detail. Results are often very inspiring, however, simplifying assumptions must be imposed: ad hoc profiles of the disc density are commonly assumed and the effects of frame-dragging and completely lacking. Astrophysical discs (e.g. accretion discs in active galactic nuclei) typically extend far beyond the relativistic domain and are fairly diluted. However, self-gravity is still essential for their structure and evolution, as well as for their radiation emission and the impact on the environment around. For example, a nuclear star cluster in a galactic centre may bear various imprints of mutual star--disc interactions, which can be recognised in observational properties, such as the relation between the central mass and stellar velocity dispersion.
Analysis of spherically symmetric black holes in Braneworld models
A. B. Pavan
2010-05-25T23:59:59.000Z
Research on black holes and their physical proprieties has been active on last 90 years. With the appearance of the String Theory and the Braneworld models as alternative descriptions of our Universe, the interest on black holes, in these context, increased. In this work we studied black holes in Braneworld models. A class of spherically symmetric black holes is investigaded as well its stability under general perturbations. Thermodynamic proprieties and quasi-normal modes are discussed. The black holes studied are the SM (zero mass) and CFM solutions, obtained by Casadio {\\it et al.} and Bronnikov {\\it et al.}. The geometry of bulk is unknown. However the Campbell-Magaard Theorem guarantees the existence of a 5-dimensional solution in the bulk whose projection on the brane is the class of black holes considered. They are stable under scalar perturbations. Quasi-normal modes were observed in both models. The tail behavior of the perturbations is the same. The entropy upper bound of a body absorved by the black holes studied was calculated. This limit turned out to be independent of the black hole parameters.
Thermodynamical instability of black holes
V. V. Kiselev
2012-08-07T23:59:59.000Z
In contrast to Hawking radiation of black hole with a given spacetime structure, we consider a competitive transition due to a heat transfer from a hotter inner horizon to a colder outer horizon of Kerr black hole, that results in a stable thermodynamical state of extremal black hole. In this process, by supposing an emission of gravitational quanta, we calculate the mass of extremal black hole in the final state of transition.
Towards noncommutative quantum black holes
Lopez-Dominguez, J. C.; Obregon, O.; Sabido, M.; Ramirez, C. [Instituto de Fisica de la Universidad de Guanajuato, P.O. Box E-143, 37150 Leon Gto. (Mexico); Facultad de Ciencias Fisico Matematicas, Universidad Autonoma de Puebla, P.O. Box 1364, 72000 Puebla (Mexico)
2006-10-15T23:59:59.000Z
In this paper we study noncommutative black holes. We use a diffeomorphism between the Schwarzschild black hole and the Kantowski-Sachs cosmological model, which is generalized to noncommutative minisuperspace. Through the use of the Feynman-Hibbs procedure we are able to study the thermodynamics of the black hole, in particular, we calculate the Hawking's temperature and entropy for the noncommutative Schwarzschild black hole.
Underwood, Lance D; Norton, Ryan J; McKay, Ryan P; Mesnard, David R; Fraze, Jason D; Zediker, Mark S; Faircloth, Brian O
2014-01-14T23:59:59.000Z
There is provided for laser bottom hole assembly for providing a high power laser beam having greater than 5 kW of power for a laser mechanical drilling process to advance a borehole. This assembly utilizes a reverse Moineau motor type power section and provides a self-regulating system that addresses fluid flows relating to motive force, cooling and removal of cuttings.
M. B. Altaie
2001-05-07T23:59:59.000Z
In this paper we follow a new approach for particle creation by a localized strong gravitational field. The approach is based on a definition of the physical vacuum drawn from Heisenberg uncertainty principle. Using the fact that the gravitational field red-shifts the frequency modes of the vacuum, a condition on the minimum stregth of the gravitational field required to achieve real particle creation is derived. Application of this requirement on a Schwartzchid black hole resulted in deducing an upper limit on the region, outside the event horizon, where real particles can be created. Using this regional upper limit, and considering particle creation by black holes as a consequence of the Casimir effect, with the assumption that the created quanta are to be added to the initial energy, we deduce a natural power law for the development of the event horizon, and consequently a logarithmic law for the area spectrum of an inflating black hole. Application of the results on a cosmological model shows that if we start with a Planck-dimensional black hole, then through the process of particle creation we end up with a universe having the presently estimated critical density. Such a universe will be in a state of eternal inflation.
Bryan Webber
2006-04-06T23:59:59.000Z
In theories with large extra dimensions and TeV-scale gravity, black holes are copiously produced in particle collisions at energies well above the Planck scale. I briefly review some recent work on the phenomenology of this process, with emphasis on theoretical uncertainties and possible strategies for measuring the number of extra dimensions.
Absorption of planar massless scalar waves by Bardeen regular black holes
Caio F. B. Macedo; Luís C. B. Crispino
2014-09-09T23:59:59.000Z
Accretion of fields by black holes is a subject of great interest in physics. It is known that accretion plays a fundamental role in active galactic nuclei and in the evolution of black holes. Accretion of fundamental fields is often related to the study of absorption cross section. Basically all black holes for which absorption of fields has been studied so far present singularities. However, even within general relativity, it is possible to construct regular black holes: objects with event horizons but without singularities. Many physically motivated regular black hole solutions have been proposed in the past years, demanding the understanding of their absorption properties. We study the absorption of planar massless scalar waves by Bardeen regular black holes. We compare the absorption cross section of Bardeen and Reissner--Nordstr\\"om black holes, showing that the former always have a bigger absorption cross section for fixed values of the field frequency and of the normalized black hole charge. We also show that it is possible for a Bardeen black hole to have the same high-frequency absorption cross section of a Reissner--Nordstr\\"om black hole. Our results suggest that, in mid-to-high-frequency regimes, regular black holes can have compatible properties with black holes with singularities, as far as absorption is concerned.
Limits on New Physics from Black Holes
Clifford Cheung; Stefan Leichenauer
2014-08-02T23:59:59.000Z
Black holes emit high energy particles which induce a finite density potential for any scalar field $\\phi$ coupling to the emitted quanta. Due to energetic considerations, $\\phi$ evolves locally to minimize the effective masses of the outgoing states. In theories where $\\phi$ resides at a metastable minimum, this effect can drive $\\phi$ over its potential barrier and classically catalyze the decay of the vacuum. Because this is not a tunneling process, the decay rate is not exponentially suppressed and a single black hole in our past light cone may be sufficient to activate the decay. Moreover, decaying black holes radiate at ever higher temperatures, so they eventually probe the full spectrum of particles coupling to $\\phi$. We present a detailed analysis of vacuum decay catalyzed by a single particle, as well as by a black hole. The former is possible provided large couplings or a weak potential barrier. In contrast, the latter occurs much more easily and places new stringent limits on theories with hierarchical spectra. Finally, we comment on how these constraints apply to the standard model and its extensions, e.g. metastable supersymmetry breaking.
Clement, María E Gabach
2015-01-01T23:59:59.000Z
It is well known that celestial bodies tend to be spherical due to gravity and that rotation produces deviations from this sphericity. We discuss what is known and expected about the shape of black holes' horizons from their formation to their final, stationary state. We present some recent results showing that black hole rotation indeed manifests in the widening of their central regions, limits their global shapes and enforces their whole geometry to be close to the extreme Kerr horizon geometry at almost maximal rotation speed. The results depend only on the horizon area and angular momentum. In particular they are entirely independent of the surrounding geometry of the spacetime and of the presence of matter satisfying the strong energy condition. We also discuss the the relation of this result with the Hoop conjecture.
Black holes in massive gravity
Babichev, Eugeny
2015-01-01T23:59:59.000Z
We review the black hole solutions of the ghost-free massive gravity theory and its bimetric extension and outline the main results on the stability of these solutions against small perturbations. Massive (bi)-gravity accommodates exact black hole solutions, analogous to those of General Relativity. In addition to these solutions, hairy black holes -- solutions with no correspondent in General Relativity -- have been found numerically, whose existence is a natural consequence of the absence of the Birkhoff's theorem in these theories. The existence of extra propagating degrees of freedom, makes the stability properties of these black holes richer and more complex than those of General Relativity. In particular, the bi-Schwarzschild black hole exhibits an unstable spherically symmetric mode, while the bi-Kerr geometry is also generically unstable, both against the spherical mode and against superradiant instabilities. If astrophysical black holes are described by these solutions, the superradiant instability o...
Gia Dvali; Cesar Gomez
2012-03-29T23:59:59.000Z
According to the standard view classically black holes carry no hair, whereas quantum hair is at best exponentially weak. We show that suppression of hair is an artifact of the semi-classical treatment and that in the quantum picture hair appears as an inverse mass-square effect. Such hair is predicted in the microscopic quantum description in which a black hole represents a self-sustained leaky Bose-condensate of N soft gravitons. In this picture the Hawking radiation is the quantum depletion of the condensate. Within this picture we show that quantum black hole physics is fully compatible with continuous global symmetries and that global hair appears with the strength B/N, where B is the global charge swallowed by the black hole. For large charge this hair has dramatic effect on black hole dynamics. Our findings can have interesting astrophysical consequences, such as existence of black holes with large detectable baryonic and leptonic numbers.
Reconstructing the massive black hole cosmic history through gravitational waves
Alberto Sesana; Jonathan R. Gair; Emanuele Berti; Marta Volonteri
2010-11-25T23:59:59.000Z
The massive black holes we observe in galaxies today are the natural end-product of a complex evolutionary path, in which black holes seeded in proto-galaxies at high redshift grow through cosmic history via a sequence of mergers and accretion episodes. Electromagnetic observations probe a small subset of the population of massive black holes (namely, those that are active or those that are very close to us), but planned space-based gravitational-wave observatories such as the Laser Interferometer Space Antenna (LISA) can measure the parameters of ``electromagnetically invisible'' massive black holes out to high redshift. In this paper we introduce a Bayesian framework to analyze the information that can be gathered from a set of such measurements. Our goal is to connect a set of massive black hole binary merger observations to the underlying model of massive black hole formation. In other words, given a set of observed massive black hole coalescences, we assess what information can be extracted about the underlying massive black hole population model. For concreteness we consider ten specific models of massive black hole formation, chosen to probe four important (and largely unconstrained) aspects of the input physics used in structure formation simulations: seed formation, metallicity ``feedback'', accretion efficiency and accretion geometry. For the first time we allow for the possibility of ``model mixing'', by drawing the observed population from some combination of the ``pure'' models that have been simulated. A Bayesian analysis allows us to recover a posterior probability distribution for the ``mixing parameters'' that characterize the fractions of each model represented in the observed distribution. Our work shows that LISA has enormous potential to probe the underlying physics of structure formation.
Formation and Evolution of Galactic Black Holes
F. Combes
2002-08-06T23:59:59.000Z
The main requirements for fueling an active galactic nucleus and to form massive black holes are reviewed. Low-luminosity AGN can be fueled easily from the local star clusters, near the nucleus, and the various stellar processes are described. Above a certain luminosity (and therefore accretion rate) large-scale gas flows from galactic scales are required. These can be driven by gravity torques of non-axisymmetric perturbations, such as bars, spirals, galaxy interactions. Observational evidence that these mechanisms are in action is found for high enough luminosities. It is very frequent that starbursts are also triggered through the same mechanisms, and the dense nuclear star clusters formed provide fuel for the AGN over a longer time-scale. Secular internal evolution and more violent evolution through interactions and mergers contribute to grow both a massive black hole and a bulge, and this could explain the observed proportionality relation between the mass of these two components.
Slant hole completion test. Final report
Mann, R.L.
1993-07-01T23:59:59.000Z
One of the Department of Energy`s (DOE) Strategies and Objectives in the Natural Gas Program is to conduct activities to transfer technology from R&D programs to potential users. The Slant Hole Completion Test has achieved exactly this objective. The Slant Hole site is essentially the same as the Multiwell site and is located in the southeastern portion of the Piceance Basin near Rifle, Colorado. The Piceance Basin is typical of the Western low permeability basins that contain thick sequences of sands, silts and coals deposited during the Cretaceous period. These sequences contain vast amounts of natural gas but have proven to be resistant to commercial production because of the low permeability of the host rocks. Using the knowledge gained from the DOE`s earlier Multiwell experiment, the SHCT-1 was drilled to demonstrate that by intersecting the natural fractures found in these ``tight rocks,`` commercial gas production can be obtained.
Observational Evidence for Black Holes
Ramesh Narayan; Jeffrey E. McClintock
2014-07-20T23:59:59.000Z
Astronomers have discovered two populations of black holes: (i) stellar-mass black holes with masses in the range 5 to 30 solar masses, millions of which are present in each galaxy in the universe, and (ii) supermassive black holes with masses in the range 10^6 to 10^{10} solar masses, one each in the nucleus of every galaxy. There is strong circumstantial evidence that all these objects are true black holes with event horizons. The measured masses of supermassive black hole are strongly correlated with properties of their host galaxies, suggesting that these black holes, although extremely small in size, have a strong influence on the formation and evolution of entire galaxies. Spin parameters have recently been measured for a handful of black holes. Based on the data, there is an indication that the kinetic power of at least one class of relativistic jet ejected from accreting black holes may be correlated with black hole spin. If verified, it would suggest that these jets are powered by a generalized Penrose process mediated by magnetic fields.
S. N. Dolya
2014-10-18T23:59:59.000Z
This article considers an opportunity of disinfecting a part of the Earth surface, occupying a large area of ten thousand square kilometers. The sunlight will cause dissociation of molecular bromine into atoms; each bromine atom kills thirty thousand molecules of ozone. Each bromine plate has a mass of forty milligrams grams and destroys ozone in the area of hundred square meters. Thus, to form the ozone hole over the area of ten thousand square kilometers, it is required to have the total mass of bromine equal to the following four tons.
Supermassive black holes from OASIS and SAURON integral-field kinematics
M. Cappellari; R. Bacon; R. L. Davies; P. T. de Zeeuw; E. Emsellem; J. Falcon-Barroso; D. Krajnovic; H. Kuntschner; R. M. McDermid; R. F. Peletier; M. Sarzi; R. C. E. van den Bosch; G. van de Ven
2007-09-18T23:59:59.000Z
Supermassive black holes are a key element in our understanding of how galaxies form. Most of the progress in this very active field of research is based on just ~30 determinations of black hole mass, accumulated over the past decade. We illustrate how integral-field spectroscopy, and in particular our OASIS modeling effort, can help improve the current situation.
Supermassive black holes from OASIS and SAURON integral-field kinematics
Cappellari, M; Davies, R L; De Zeeuw, P T; Emsellem, E; Falcon-Barroso, J; Krajnovic, D; Kuntschner, H; McDermid, R M; Peletier, R F; Sarzi, M; Bosch, R C E van den; van de Ven, G
2007-01-01T23:59:59.000Z
Supermassive black holes are a key element in our understanding of how galaxies form. Most of the progress in this very active field of research is based on just ~30 determinations of black hole mass, accumulated over the past decade. We illustrate how integral-field spectroscopy, and in particular our OASIS modeling effort, can help improve the current situation.
The Ozone Hole Some perspective
Toohey, Darin W.
The Ozone Hole · Some perspective · The British Antarctic Survey · The "Ozone Hole" · International of the predicted ozone losses! This was quite a controversy. Ultimately, ozone losses started appearing in the late 1980s (see Figure below), but by then, there was already a credibility issue for ozone scientists. #12
Optical black holes and solitons
Shawn Westmoreland
2010-12-21T23:59:59.000Z
We exhibit a static, cylindrically symmetric, exact solution to the Euler-Heisenberg field equations (EHFE) and prove that its effective geometry contains (optical) black holes. It is conjectured that there are also soliton solutions to the EHFE which contain black hole geometries.
R. B. Mann
1997-05-06T23:59:59.000Z
I demonstrate that, under certain circumstances, regions of negative energy density can undergo gravitational collapse into a black hole. The resultant exterior black hole spacetimes necessarily have negative mass and non-trivial topology. A full theory of quantum gravity, in which topology-changing processes take place, could give rise to such spacetimes.
Strings, higher curvature corrections, and black holes
Thomas Mohaupt
2005-12-05T23:59:59.000Z
We review old and recent results on subleading contributions to black hole entropy in string theory.
Alternate Explosions: Collapse and Accretion Events with Red Holes instead of Black Holes
James S. Graber
1999-08-10T23:59:59.000Z
A red hole is "just like a black hole" except it lacks an event horizon and a singularity. As a result, a red hole emits much more energy than a black hole during a collapse or accretion event. We consider how a red hole solution can solve the "energy crisis" and power extremely energetic gamma ray bursts and hypernovae.
ON THE PROSPECT OF CONSTRAINING BLACK HOLE SPIN THROUGH X-RAY SPECTROSCOPY OF HOTSPOTS
Yaqoob, Tahir
Future X-ray instrumentation is expected to allow us to significantly improve the constraints derived from the Fe?K lines in active galactic nuclei, such as the black hole angular momentum (spin) and the inclination angle ...
Thermodynamics of regular black hole
Yun Soo Myung; Yong-Wan Kim; Young-Jai Park
2008-09-21T23:59:59.000Z
We investigate thermodynamics for a magnetically charged regular black hole (MCRBH), which comes from the action of general relativity and nonlinear electromagnetics, comparing with the Reissner-Norstr\\"om (RN) black hole in both four and two dimensions after dimensional reduction. We find that there is no thermodynamic difference between the regular and RN black holes for a fixed charge $Q$ in both dimensions. This means that the condition for either singularity or regularity at the origin of coordinate does not affect the thermodynamics of black hole. Furthermore, we describe the near-horizon AdS$_2$ thermodynamics of the MCRBH with the connection of the Jackiw-Teitelboim theory. We also identify the near-horizon entropy as the statistical entropy by using the AdS$_2$/CFT$_1$ correspondence.
Black Hole Interior Mass Formula
Parthapratim Pradhan
2014-05-06T23:59:59.000Z
We argue by explicit computations that, although the area product, horizon radii product, entropy product and \\emph {irreducible mass product} of the event horizon and Cauchy horizon are universal, the \\emph{surface gravity product}, \\emph{surface temperature product} and \\emph{Komar energy product} of the said horizons do not seem to be universal for Kerr-Newman (KN) black hole space-time. We show the black hole mass formula on the \\emph{Cauchy horizon} following the seminal work by Smarr\\cite{smarr} for the outer horizon. We also prescribed the \\emph{four} laws of black hole mechanics for the \\emph{inner horizon}. New definition of the extremal limit of a black hole is discussed.
A. Brotas
2006-09-01T23:59:59.000Z
The coordinate system $(\\bar{x},\\bar{t})$ defined by $r = 2m + K\\bar{x}- c K \\bar{t}$ and $t=\\bar{x}/cK - 1 /cK \\int_{r_a}^r (1- 2m/r + K^2)^{1/2} (1 - 2m/r)^{-1}dr$ allow us to write the Schwarzschild metric in the form: \\[ds^2=c^2 d\\bar{t}^2 + (W^2/K^2 - 2W/K) d\\bar{x}^2 + 2c (1 + W/K) d\\bar{x}d\\bar{t} - r^2 (d\\theta^2 + cos^2\\theta d\\phi^2)\\] with $W=(1 - 2m/r + K^2)^{1/2}$, in which the coefficients' pathologies are moved to $r_K = 2m/(1+K^2)$. This new coordinate system is used to study the entrance into a black hole of a rigid line (a line in which the shock waves propagate with velocity c).
Pilgrim Hot Springs, Alaska | Department of Energy
Broader source: Energy.gov (indexed) [DOE]
new and old data sets to develop conceptual model. Confirm this model through drilling two confirmation slim holes. validationholdmannpilgrimhotsprings.pdf More...
Sadeghi, J
2015-01-01T23:59:59.000Z
As we know, the cosmological constant in different theories of gravity acts as a thermodynamics variable. The cosmological constant exists in different actions of gravity and also appears in the solution of such theories. These lead to use the black hole as a heat engines. Also, there are two values for the cosmological constant as positive and negative values. The case of negative cosmological constant supplies a natural realization of these engines in terms of the field theory description of the fluids to which they are holographically dual. In this paper, we are going to define heat engines for two different black holes as Dyonic BH and Kerr BH. And also, we calculate maximum efficiency for two black holes.
J. Sadeghi; Kh. Jafarzade
2015-04-29T23:59:59.000Z
As we know, the cosmological constant in different theories of gravity acts as a thermodynamics variable. The cosmological constant exists in different actions of gravity and also appears in the solution of such theories. These lead to use the black hole as a heat engines. Also, there are two values for the cosmological constant as positive and negative values. The case of negative cosmological constant supplies a natural realization of these engines in terms of the field theory description of the fluids to which they are holographically dual. In this paper, we are going to define heat engines for two different black holes as Dyonic BH and Kerr BH. And also, we calculate maximum efficiency for two black holes.
Energy on black hole spacetimes
Alejandro Corichi
2012-07-18T23:59:59.000Z
We consider the issue of defining energy for test particles on a background black hole spacetime. We revisit the different notions of energy as defined by different observers. The existence of a time-like isometry allows for the notion of a total conserved energy to be well defined, and subsequently the notion of a gravitational potential energy is also meaningful. We then consider the situation in which the test particle is adsorbed by the black hole, and analyze the energetics in detail. In particular, we show that the notion of horizon energy es defined by the isolated horizons formalism provides a satisfactory notion of energy compatible with the particle's conserved energy. As another example, we comment a recent proposal to define energy of the black hole as seen by an observer at rest. This account is intended to be pedagogical and is aimed at the level of and as a complement to the standard textbooks on the subject.
Introduction to Black Hole Evaporation
Pierre-Henry Lambert
2014-01-16T23:59:59.000Z
These lecture notes are an elementary and pedagogical introduction to the black hole evaporation, based on a lecture given by the author at the Ninth Modave Summer School in Mathematical Physics and are intended for PhD students. First, quantum field theory in curved spacetime is studied and tools needed for the remaining of the course are introduced. Then, quantum field theory in Rindler spacetime in 1+1 dimensions and in the spacetime of a spherically collapsing star are considered, leading to Unruh and Hawking effects, respectively. Finally, some consequences such as thermodynamics of black holes and information loss paradox are discussed.
Hawking Emission and Black Hole Thermodynamics
Don N. Page
2006-12-18T23:59:59.000Z
A brief review of Hawking radiation and black hole thermodynamics is given, based largely upon hep-th/0409024.
High precision, rapid laser hole drilling
Chang, Jim J.; Friedman, Herbert W.; Comaskey, Brian J.
2013-04-02T23:59:59.000Z
A laser system produces a first laser beam for rapidly removing the bulk of material in an area to form a ragged hole. The laser system produces a second laser beam for accurately cleaning up the ragged hole so that the final hole has dimensions of high precision.
Signatures of black holes at the LHC
Marco Cavaglia; Romulus Godang; Lucien M. Cremaldi; Donald J. Summers
2007-07-02T23:59:59.000Z
Signatures of black hole events at CERN's Large Hadron Collider are discussed. Event simulations are carried out with the Fortran Monte Carlo generator CATFISH. Inelasticity effects, exact field emissivities, color and charge conservation, corrections to semiclassical black hole evaporation, gravitational energy loss at formation and possibility of a black hole remnant are included in the analysis.
High precision, rapid laser hole drilling
Chang, Jim J.; Friedman, Herbert W.; Comaskey, Brian J.
2007-03-20T23:59:59.000Z
A laser system produces a first laser beam for rapidly removing the bulk of material in an area to form a ragged hole. The laser system produces a second laser beam for accurately cleaning up the ragged hole so that the final hole has dimensions of high precision.
High precision, rapid laser hole drilling
Chang, Jim J.; Friedman, Herbert W.; Comaskey, Brian J.
2005-03-08T23:59:59.000Z
A laser system produces a first laser beam for rapidly removing the bulk of material in an area to form a ragged hole. The laser system produces a second laser beam for accurately cleaning up the ragged hole so that the final hole has dimensions of high precision.
Absorption cross section in Lifshitz black hole
Taeyoon Moon; Yun Soo Myung
2012-10-05T23:59:59.000Z
We derive the absorption cross section of a minimally coupled scalar in the Lifshitz black hole obtained from the new massive gravity. The absorption cross section reduces to the horizon area in the low energy and massless limit of s-wave mode propagation, indicating that the Lifshitz black hole also satisfies the universality of low energy absorption cross section for black holes.
Einstein, Black Holes Gravitational Waves
Cook, Greg
1 #12;Einstein, Black Holes and Gravitational Waves Gregory B. Cook Wake Forest University 2 #12;Einstein's Miraculous Year: 1905 · Einstein, A. "¨Uber einen die Erzeugung und Verwandlung des Lichtes Concerning the Production and Transformation of Light. · Einstein, A. "¨Uber die von der molekularkinetischen
Fenimore, Edward E. [Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
2014-10-06T23:59:59.000Z
Pinhole photography has made major contributions to astrophysics through the use of “coded apertures”. Coded apertures were instrumental in locating gamma-ray bursts and proving that they originate in faraway galaxies, some from the birth of black holes from the first stars that formed just after the big bang.
TIPS TO REMAIN SLIM * Set realistic goals.
Srivastava, Kumar Vaibhav
a week. * Aerobic exercise like jogging, swimming, cycling, running accelerates weight loss. Consult in the morning. * Go for skimmed milk. * As far as possible avoid weight loss supplements. * When you have a physician before starting any weight loss program. Aerobic exercise combined with healthy eating
Black Holes in Galaxy Mergers: Evolution of Quasars
Philip F. Hopkins; Lars Hernquist; Thomas J. Cox; Tiziana Di Matteo; Paul Martini; Brant Robertson; Volker Springel
2005-06-13T23:59:59.000Z
Based on numerical simulations of gas-rich galaxy mergers, we discuss a model in which quasar activity is tied to the self-regulated growth of supermassive black holes in galaxies. Nuclear inflow of gas attending a galaxy collision triggers a starburst and feeds black hole growth, but for most of the duration of the starburst, the black hole is heavily obscured by surrounding gas and dust which limits the visibility of the quasar, especially at optical and UV wavelengths. Eventually, feedback energy from accretion heats the gas and expels it in a powerful wind, leaving a 'dead quasar'. Between buried and dead phases there is a window during which the galaxy would be seen as a luminous quasar. Because the black hole mass, radiative output, and distribution of obscuring gas and dust all evolve strongly with time, the duration of this phase of observable quasar activity depends on both the waveband and imposed luminosity threshold. We determine the observed and intrinsic lifetimes as a function of luminosity and frequency, and calculate observable lifetimes ~10 Myr for bright quasars in the optical B-band, in good agreement with empirical estimates and much smaller than the black hole growth timescales ~100 Myr, naturally producing a substantial population of 'buried' quasars. However, observed and intrinsic energy outputs converge in the IR and hard X-ray bands as attenuation becomes weaker and chances of observation greatly increase. We obtain the distribution of column densities along sightlines in which the quasar is seen above a given luminosity, and find that our result agrees remarkably well with observed estimates of the column density distribution from the SDSS for appropriate luminosity thresholds. (Abridged)
Black Hole Radiation and Volume Statistical Entropy
Mario Rabinowitz
2005-06-29T23:59:59.000Z
The simplest possible equation for Hawking radiation, and other black hole radiated power is derived in terms of black hole density. Black hole density also leads to the simplest possible model of a gas of elementary constituents confined inside a gravitational bottle of Schwarzchild radius at tremendous pressure, which yields identically the same functional dependence as the traditional black hole entropy. Variations of Sbh can be obtained which depend on the occupancy of phase space cells. A relation is derived between the constituent momenta and the black hole radius which is similar to the Compton wavelength relation.
Black hole mimickers: Regular versus singular behavior
Lemos, Jose P. S.; Zaslavskii, Oleg B. [Centro Multidisciplinar de Astrofisica, CENTRA, Departamento de Fisica, Instituto Superior Tecnico-IST, Universidade Tecnica de Lisboa-UTL, Avenida Rovisco Pais 1, 1049-001 Lisboa (Portugal); Astronomical Institute of Kharkov, V. N. Karazin National University, 35 Sumskaya Street, Kharkov, 61022 (Ukraine)
2008-07-15T23:59:59.000Z
Black hole mimickers are possible alternatives to black holes; they would look observationally almost like black holes but would have no horizon. The properties in the near-horizon region where gravity is strong can be quite different for both types of objects, but at infinity it could be difficult to discern black holes from their mimickers. To disentangle this possible confusion, we examine the near-horizon properties, and their connection with far away asymptotic properties, of some candidates to black mimickers. We study spherically symmetric uncharged or charged but nonextremal objects, as well as spherically symmetric charged extremal objects. Within the uncharged or charged but nonextremal black hole mimickers, we study nonextremal {epsilon}-wormholes on the threshold of the formation of an event horizon, of which a subclass are called black foils, and gravastars. Within the charged extremal black hole mimickers we study extremal {epsilon}-wormholes on the threshold of the formation of an event horizon, quasi-black holes, and wormholes on the basis of quasi-black holes from Bonnor stars. We elucidate whether or not the objects belonging to these two classes remain regular in the near-horizon limit. The requirement of full regularity, i.e., finite curvature and absence of naked behavior, up to an arbitrary neighborhood of the gravitational radius of the object enables one to rule out potential mimickers in most of the cases. A list ranking the best black hole mimickers up to the worst, both nonextremal and extremal, is as follows: wormholes on the basis of extremal black holes or on the basis of quasi-black holes, quasi-black holes, wormholes on the basis of nonextremal black holes (black foils), and gravastars. Since in observational astrophysics it is difficult to find extremal configurations (the best mimickers in the ranking), whereas nonextremal configurations are really bad mimickers, the task of distinguishing black holes from their mimickers seems to be less difficult than one could think of it.
Black Hole Evaporation as a Nonequilibrium Process
Hiromi Saida
2008-11-11T23:59:59.000Z
When a black hole evaporates, there arises a net energy flow from the black hole into its outside environment due to the Hawking radiation and the energy accretion onto black hole. Exactly speaking, due to the net energy flow, the black hole evaporation is a nonequilibrium process. To study details of evaporation process, nonequilibrium effects of the net energy flow should be taken into account. In this article we simplify the situation so that the Hawking radiation consists of non-self-interacting massless matter fields and also the energy accretion onto the black hole consists of the same fields. Then we find that the nonequilibrium nature of black hole evaporation is described by a nonequilibrium state of that field, and we formulate nonequilibrium thermodynamics of non-self-interacting massless fields. By applying it to black hole evaporation, followings are shown: (1) Nonequilibrium effects of the energy flow tends to accelerate the black hole evaporation, and, consequently, a specific nonequilibrium phenomenon of semi-classical black hole evaporation is suggested. Furthermore a suggestion about the end state of quantum size black hole evaporation is proposed in the context of information loss paradox. (2) Negative heat capacity of black hole is the physical essence of the generalized second law of black hole thermodynamics, and self-entropy production inside the matter around black hole is not necessary to ensure the generalized second law. Furthermore a lower bound for total entropy at the end of black hole evaporation is given. A relation of the lower bound with the so-called covariant entropy bound conjecture is interesting but left as an open issue.
BSW process of the slowly evaporating charged black hole
Liancheng Wang; Feng He; Xiangyun Fu
2015-02-09T23:59:59.000Z
In this paper, we study the BSW process of the slowly evaporating charged black hole. It can be found that the BSW process will also arise near black hole horizon when the evaporation of charged black hole is very slow. But now the background black hole does not have to be an extremal black hole, and it will be approximately an extremal black hole unless it is nearly a huge stationary black hole.
Down hole periodic seismic generator
Hardee, Harry C. (Albuquerque, NM); Hills, Richard G. (Las Cruces, NM); Striker, Richard P. (Albuquerque, NM)
1989-01-01T23:59:59.000Z
A down hole periodic seismic generator system for transmitting variable frequency, predominantly shear-wave vibration into earth strata surrounding a borehole. The system comprises a unitary housing operably connected to a well head by support and electrical cabling and contains clamping apparatus for selectively clamping the housing to the walls of the borehole. The system further comprises a variable speed pneumatic oscillator and a self-contained pneumatic reservoir for producing a frequency-swept seismic output over a discrete frequency range.
"Meissner effect" and Blandford-Znajek mechanism in conductive black hole magnetospheres
S. S. Komissarov; J. C. McKinney
2007-02-14T23:59:59.000Z
The expulsion of axisymmetric magnetic field from the event horizons of rapidly rotating black holes has been seen as an astrophysically important effect that may significantly reduce or even nullify the efficiency of the Blandford-Znajek mechanism of powering the relativistic jets in Active Galactic Nuclei and Gamma Ray Bursts. However, this Meissner-like effect is seen in vacuum solutions of black hole electrodynamics whereas the Blandford-Znajek mechanism is concerned with plasma-filled magnetospheres. In this paper we argue that conductivity dramatically changes the properties of axisymmetric electromagnetic solutions -- even for a maximally rotating Kerr black hole the magnetic field is pulled inside the event horizon. Moreover, the conditions resulting in outgoing Poynting flux in the Blandford-Znajek mechanism exist not on the event horizon but everywhere within the black hole ergosphere. Thus, the Meissner effect is unlikely to be of interest in astrophysics of black holes, at least not in the way this has been suggested so far. These conclusions are supported by the results of time-dependent numerical simulations with three different computer codes. The test problems involve black holes with the rotation parameter ranging from $a=0.999$ to $a=1$. The pure electrodynamic simulations deal with the structure of conductive magnetospheres of black holes placed in a uniform-at-infinity magnetic field (Wald's problem) and the magnetohydrodynamic simulations are used to study the magnetospheres arising in the problem of disk accretion.
Supermassive Black Hole Growth and Merger Rates from Cosmological N-body Simulations
Miroslav Micic; Kelly Holley-Bockelmann; Steinn Sigurdsson; Tom Abel
2007-03-20T23:59:59.000Z
Understanding how seed black holes grow into intermediate and supermassive black holes (IMBHs and SMBHs, respectively) has important implications for the duty-cycle of active galactic nuclei (AGN), galaxy evolution, and gravitational wave astronomy. Most studies of the cosmological growth and merger history of black holes have used semianalytic models and have concentrated on SMBH growth in luminous galaxies. Using high resolution cosmological N-body simulations, we track the assembly of black holes over a large range of final masses -- from seed black holes to SMBHs -- over widely varying dynamical histories. We used the dynamics of dark matter halos to track the evolution of seed black holes in three different gas accretion scenarios. We have found that growth of Sagittarius A* - size SMBH reaches its maximum mass M_{SMBH}~10^6Msun at z~6 through early gaseous accretion episodes, after which it stays at near constant mass. At the same redshift, the duty-cycle of the host AGN ends, hence redshift z=6 marks the transition from an AGN to a starburst galaxy which eventually becomes the Milky Way. By tracking black hole growth as a function of time and mass, we estimate that the IMBH merger rate reaches a maximum of R_{max}=55 yr^-1 at z=11. From IMBH merger rates we calculate N_{ULX}=7 per Milky Way type galaxy per redshift in redshift range 2
Charged spinning black holes as particle accelerators
Wei Shaowen; Liu Yuxiao; Guo Heng; Fu Chune [Institute of Theoretical Physics, Lanzhou University, Lanzhou 730000 (China)
2010-11-15T23:59:59.000Z
It has recently been pointed out that the spinning Kerr black hole with maximal spin could act as a particle collider with arbitrarily high center-of-mass energy. In this paper, we will extend the result to the charged spinning black hole, the Kerr-Newman black hole. The center-of-mass energy of collision for two uncharged particles falling freely from rest at infinity depends not only on the spin a but also on the charge Q of the black hole. We find that an unlimited center-of-mass energy can be approached with the conditions: (1) the collision takes place at the horizon of an extremal black hole; (2) one of the colliding particles has critical angular momentum; (3) the spin a of the extremal black hole satisfies (1/{radical}(3)){<=}(a/M){<=}1, where M is the mass of the Kerr-Newman black hole. The third condition implies that to obtain an arbitrarily high energy, the extremal Kerr-Newman black hole must have a large value of spin, which is a significant difference between the Kerr and Kerr-Newman black holes. Furthermore, we also show that, for a near-extremal black hole, there always exists a finite upper bound for center-of-mass energy, which decreases with the increase of the charge Q.
Submicron patterned metal hole etching
McCarthy, Anthony M. (Menlo Park, CA); Contolini, Robert J. (Lake Oswego, OR); Liberman, Vladimir (Needham, MA); Morse, Jeffrey (Martinez, CA)
2000-01-01T23:59:59.000Z
A wet chemical process for etching submicron patterned holes in thin metal layers using electrochemical etching with the aid of a wetting agent. In this process, the processed wafer to be etched is immersed in a wetting agent, such as methanol, for a few seconds prior to inserting the processed wafer into an electrochemical etching setup, with the wafer maintained horizontal during transfer to maintain a film of methanol covering the patterned areas. The electrochemical etching setup includes a tube which seals the edges of the wafer preventing loss of the methanol. An electrolyte composed of 4:1 water: sulfuric is poured into the tube and the electrolyte replaces the wetting agent in the patterned holes. A working electrode is attached to a metal layer of the wafer, with reference and counter electrodes inserted in the electrolyte with all electrodes connected to a potentiostat. A single pulse on the counter electrode, such as a 100 ms pulse at +10.2 volts, is used to excite the electrochemical circuit and perform the etch. The process produces uniform etching of the patterned holes in the metal layers, such as chromium and molybdenum of the wafer without adversely effecting the patterned mask.
Quantum Geometry and Black Holes
G., J Fernando Barbero
2015-01-01T23:59:59.000Z
We present an overall picture of the advances in the description of black hole physics from the perspective of loop quantum gravity. After an introduction that discusses the main conceptual issues we present some details about the classical and quantum geometry of isolated horizons and their quantum geometry and then use this scheme to give a natural definition of the entropy of black holes. The entropy computations can be neatly expressed in the form of combinatorial problems solvable with the help of methods based on number theory and the use of generating functions. The recovery of the Bekenstein-Hawking law and corrections to it is explained in some detail. After this, due attention is paid to the discussion of semiclassical issues. An important point in this respect is the proper interpretation of the horizon area as the energy that should appear in the statistical-mechanical treatment of the black hole model presented here. The chapter ends with a comparison between the microscopic and semiclassical app...
Black holes are almost optimal quantum cloners
C. Adami; G. Ver Steeg
2015-04-15T23:59:59.000Z
If black holes were able to clone quantum states, a number of paradoxes in black hole physics would disappear. However, the linearity of quantum mechanics forbids exact cloning of quantum states. Here we show that black holes indeed clone incoming quantum states with a fidelity that depends on the black hole's absorption coefficient, without violating the no-cloning theorem because the clones are only approximate. Perfectly reflecting black holes are optimal universal "quantum cloning machines" and operate on the principle of stimulated emission, exactly as their quantum optical counterparts. In the limit of perfect absorption, the fidelity of clones is equal to what can be obtained via quantum state estimation methods. But for any absorption probability less than one, the cloning fidelity is nearly optimal as long as $\\omega/T\\geq10$, a common parameter for modest-sized black holes.
Remarks on Renormalization of Black Hole Entropy
Sang Pyo Kim; Sung Ku Kim; Kwang-Sup Soh; Jae Hyung Yee
1996-07-07T23:59:59.000Z
We elaborate the renormalization process of entropy of a nonextremal and an extremal Reissner-Nordstr\\"{o}m black hole by using the Pauli-Villars regularization method, in which the regulator fields obey either the Bose-Einstein or Fermi-Dirac distribution depending on their spin-statistics. The black hole entropy involves only two renormalization constants. We also discuss the entropy and temperature of the extremal black hole.
Hole cleaning requirements with seabed returns
Nordt, David Paul
1988-01-01T23:59:59.000Z
of different non-Newtonian fluids 56 INTRODUCTION A drilling fluid is used for removing cuttings from the hole, controlling subsurface pressures, preventing caving-in of the formations, suspension of cuttings, weighting materials, and many other uses... of the hole. The drilling problems related to hole cleaning can occur at low as well as high annular velocities. Cuttings can travel no faster than the fluid in which they are transported; however, they can travel more slowly. Their fall (slip) rate...
Probing the Constituent Structure of Black Holes
Lukas Gruending; Stefan Hofmann; Sophia Müller; Tehseen Rug
2014-12-12T23:59:59.000Z
We calculate the cross section for scattering processes between graviton emitters on the near side of a Schwarzschild surface and absorbers on its far side, that is black hole constituents. We show that these scatterings allow to directly extract structural observables such as the momentum distribution of black hole constituents. For this we employ a quantum bound state description originally developed in quantum chromodynamics and recently applied to general relativity that allows to consider black holes in a relativistic Hartree like framework.
Black hole initial data without elliptic equations
István Rácz; Jeffrey Winicour
2015-02-24T23:59:59.000Z
We explore whether a new method to solve the constraints of Einstein's equations, which does not involve elliptic equations, can be applied to provide initial data for black holes. We show that this method can be successfully applied to a nonlinear perturbation of a Schwarzschild black hole by establishing the well-posedness of the resulting constraint problem. We discuss its possible generalization to the boosted, spinning multiple black hole problem.
Absorption cross section of RN black hole
Sini R.; V. C. Kuriakose
2007-08-23T23:59:59.000Z
The behavior of a charged scalar field in the RN black hole space time is studied using WKB approximation. In the present work it is assumed that matter waves can get reflected from the event horizon. Using this effect, the Hawking temperature and the absorption cross section for RN black hole placed in a charged scalar field are calculated. The absorption cross section $\\sigma _{abs}$ is found to be inversely proportional to square of the Hawking temperature of the black hole.
Black holes with massive graviton hair
Richard Brito; Vitor Cardoso; Paolo Pani
2013-09-03T23:59:59.000Z
No-hair theorems exclude the existence of nontrivial scalar and massive vector hair outside four-dimensional, static, asymptotically flat black-hole spacetimes. We show, by explicitly building nonlinear solutions, that black holes can support massive graviton hair in theories of massive gravity. These hairy solutions are, most likely, the generic end state of the recently discovered monopole instability of Schwarzschild black holes in massive graviton theories.
Supermassive black holes (SMBH) and formation of galaxies
F. Combes
2003-07-31T23:59:59.000Z
The recently confirmed correlation between the mass of SMBH and bulges of galaxies (and their central velocity dispersion), suggest a common formation scenario for galaxies and their central black holes. Common fueling can be invoked through internal dynamical processes, external accretion, and hierarchical merging of structures. The success of recent theories is reviewed, as the self-regulated growth of both bulges and SMBHs, the predicted AGN statistics, when activity is triggered by accretion and mergers, the predicted frequency of binary SMBH and consequences. In particular, the SMBH growth problem can now be revised, invoking intermediate-mass black holes (IMBH) as BH seeds in the early universe. As a by-product, the merger of binary SMBHs help to heat and destroy central stellar cusps. Remaining problems are mentioned.
Thermoelectric DC conductivities from black hole horizons
Aristomenis Donos; Jerome P. Gauntlett
2014-10-14T23:59:59.000Z
An analytic expression for the DC electrical conductivity in terms of black hole horizon data was recently obtained for a class of holographic black holes exhibiting momentum dissipation. We generalise this result to obtain analogous expressions for the DC thermoelectric and thermal conductivities. We illustrate our results using some holographic Q-lattice black holes as well as for some black holes with linear massless axions, in both $D=4$ and $D=5$ bulk spacetime dimensions, which include both spatially isotropic and anisotropic examples. We show that some recently constructed ground states of holographic Q-lattices, which can be either electrically insulating or metallic, are all thermal insulators.
Mineral Test Hole Regulatory Act (Tennessee)
Broader source: Energy.gov [DOE]
The Mineral Hole Regulatory Act is applicable to any person (individual, corporation, company, association, joint venture, partnership, receiver, trustee, guardian, executor, administrator,...
Black Holes: from Speculations to Observations
Thomas W. Baumgarte
2006-04-13T23:59:59.000Z
This paper provides a brief review of the history of our understanding and knowledge of black holes. Starting with early speculations on ``dark stars'' I discuss the Schwarzschild "black hole" solution to Einstein's field equations and the development of its interpretation from "physically meaningless" to describing the perhaps most exotic and yet "most perfect" macroscopic object in the universe. I describe different astrophysical black hole populations and discuss some of their observational evidence. Finally I close by speculating about future observations of black holes with the new generation of gravitational wave detectors.
Lower Dimensional Black Holes: Inside and Out
R. B. Mann
1995-01-27T23:59:59.000Z
I survey the physics of black holes in two and three spacetime dimensions, with special attention given to an understanding of their exterior and interior properties.
Approximate initial data for binary black holes
Kenneth A. Dennison; Thomas W. Baumgarte; Harald P. Pfeiffer
2006-08-26T23:59:59.000Z
We construct approximate analytical solutions to the constraint equations of general relativity for binary black holes of arbitrary mass ratio in quasicircular orbit. We adopt the puncture method to solve the constraint equations in the transverse-traceless decomposition and consider perturbations of Schwarzschild black holes caused by boosts and the presence of a binary companion. A superposition of these two perturbations then yields approximate, but fully analytic binary black hole initial data that are accurate to first order in the inverse of the binary separation and the square of the black holes' momenta.
Herdeiro, Carlos A R
2014-01-01T23:59:59.000Z
We show that scalar hair can be added to rotating, vacuum black holes of general relativity. These hairy black holes (HBHs) clarify a lingering question concerning gravitational solitons: if a black hole can be added at the centre of a boson star, as it typically can for other solitons. We argue that it can, but only if it is spinning. The existence of such HBHs is related to the Kerr superradiant instability triggered by a massive scalar field. This connection leads to the following conjecture: a (hairless) black hole which is afflicted by the superradiant instability of a given field must allow hairy generalizations with that field.
Rotating embedded black holes: Entropy and Hawking's radiation
Ng Ibohal
2004-12-27T23:59:59.000Z
In this paper we derive a class of rotating embedded black holes. Then we study Hawking's radiation effects on these embedded black holes. The surface gravity, entropy and angular velocity are given for each of these black holes.
Black Holes at the LHC: Progress since 2002
Park, Seong Chan [FRDP, Department of Physics and Astronomy, Seoul National University, Seoul (Korea, Republic of)
2008-11-23T23:59:59.000Z
We review the recent noticeable progresses in black hole physics focusing on the up-coming super-collider, the LHC. We discuss the classical formation of black holes by particle collision, the greybody factors for higher dimensional rotating black holes, the deep implications of black hole physics to the 'energy-distance' relation, the security issues of the LHC associated with black hole formation and the newly developed Monte-Carlo generators for black hole events.
Topological Black Holes in Quantum Gravity
J. Kowalski-Glikman; D. Nowak-Szczepaniak
2000-07-31T23:59:59.000Z
We derive the black hole solutions with horizons of non-trivial topology and investigate their properties in the framework of an approach to quantum gravity being an extension of Bohm's formulation of quantum mechanics. The solutions we found tend asymptotically (for large $r$) to topological black holes. We also analyze the thermodynamics of these space-times.
Primordial black holes and asteroid danger
Alexander Shatskiy
2008-02-21T23:59:59.000Z
Probability for a primordial black hole to invade the Kuiper belt was calculated. We showed that primordial black holes of certain masses can significantly change asteroids' orbits. These events may result in disasters, local for our solar system and global for the Earth (like the Tunguska meteorite). We also estimated how often such events occur.
Dynamics of Primordial Black Hole Formation
J. C. Niemeyer; K. Jedamzik
1999-01-21T23:59:59.000Z
We present a numerical investigation of the gravitational collapse of horizon-size density fluctuations to primordial black holes (PBHs) during the radiation-dominated phase of the Early Universe. The collapse dynamics of three different families of initial perturbation shapes, imposed at the time of horizon crossing, is computed. The perturbation threshold for black hole formation, needed for estimations of the cosmological PBH mass function, is found to be $\\delta_{\\rm c} \\approx 0.7$ rather than the generally employed $\\delta_{\\rm c} \\approx 1/3$, if $\\delta$ is defined as $\\Delta M/\\mh$, the relative excess mass within the initial horizon volume. In order to study the accretion onto the newly formed black holes, we use a numerical scheme that allows us to follow the evolution for long times after formation of the event horizon. In general, small black holes (compared to the horizon mass at the onset of the collapse) give rise to a fluid bounce that effectively shuts off accretion onto the black hole, while large ones do not. In both cases, the growth of the black hole mass owing to accretion is insignificant. Furthermore, the scaling of black hole mass with distance from the formation threshold, known to occur in near-critical gravitational collapse, is demonstrated to apply to primordial black hole formation.
Black holes cannot support conformal scalar hair
T. Zannias
1994-09-14T23:59:59.000Z
It is shown that the only static asymptotically flat non-extrema black hole solution of the Einstein-conformally invariant scalar field equations having the scalar field bounded on the horizon, is the Schwarzschild one. Thus black holes cannot be endowed with conformal scalar hair of finite length.
Strings, black holes, and quantum information
Kallosh, Renata; Linde, Andrei [Department of Physics, Stanford University, Stanford, California 94305 (United States)
2006-05-15T23:59:59.000Z
We find multiple relations between extremal black holes in string theory and 2- and 3-qubit systems in quantum information theory. We show that the entropy of the axion-dilaton extremal black hole is related to the concurrence of a 2-qubit state, whereas the entropy of the STU black holes, Bogomol'nyi-Prasad-Sommerfield (BPS) as well as non-BPS, is related to the 3-tangle of a 3-qubit state. We relate the 3-qubit states with the string theory states with some number of D-branes. We identify a set of large black holes with the maximally entangled Greenberger, Horne, Zeilinger (GHZ) class of states and small black holes with separable, bipartite, and W states. We sort out the relation between 3-qubit states, twistors, octonions, and black holes. We give a simple expression for the entropy and the area of stretched horizon of small black holes in terms of a norm and 2-tangles of a 3-qubit system. Finally, we show that the most general expression for the black hole and black ring entropy in N=8 supergravity/M theory, which is given by the famous quartic Cartan E{sub 7(7)} invariant, can be reduced to Cayley's hyperdeterminant describing the 3-tangle of a 3-qubit state.
Quantum Entropy of Charged Rotating Black Holes
R. B. Mann
1996-07-10T23:59:59.000Z
I discuss a method for obtaining the one-loop quantum corrections to the tree-level entropy for a charged Kerr black hole. Divergences which appear can be removed by renormalization of couplings in the tree-level gravitational action in a manner similar to that for a static black hole.
Phosphine Oxide Based Electron Transporting and Hole Blocking...
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Oxide Based Electron Transporting and Hole Blocking Materials for Blue Electrophosphorescent Organic Light Emitting Phosphine Oxide Based Electron Transporting and Hole Blocking...
Three Hydrogen Bond Donor Catalysts: Oxyanion Hole Mimics and...
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Hydrogen Bond Donor Catalysts: Oxyanion Hole Mimics and Transition State Analogues. Three Hydrogen Bond Donor Catalysts: Oxyanion Hole Mimics and Transition State Analogues....
T-623: HP Business Availability Center Input Validation Hole...
Broader source: Energy.gov (indexed) [DOE]
3: HP Business Availability Center Input Validation Hole Permits Cross-Site Scripting Attacks T-623: HP Business Availability Center Input Validation Hole Permits Cross-Site...
Lake, Matthew J
2015-01-01T23:59:59.000Z
The discovery of a large number of supermassive black holes at redshifts $z> 6$, when the Universe was only nine hundred million years old, has raised the fundamental question of how such massive compact objects could form in a (cosmologically) short time interval. Each of the proposed standard scenarios for black hole formation, involving rapid accretion of seed black holes, or black hole mergers, faces severe theoretical difficulties in explaining the short time formation of supermassive objects. In the present Letter, we propose an alternative scenario for the formation of supermassive black holes in the early Universe in which energy transfer from superconducting cosmic strings, piercing small seed black holes, is the main physical process leading to rapid mass increase. The increase in mass of a primordial seed black hole pierced by two antipodal strings is estimated and it is shown that this increases linearly in time. Due to the high energy transfer rate from the cosmic strings, we find that supermassi...
Black hole and holographic dark energy
Yun Soo Myung
2007-04-11T23:59:59.000Z
We discuss the connection between black hole and holographic dark energy. We examine the issue of the equation of state (EOS) for holographic energy density as a candidate for the dark energy carefully. This is closely related to the EOS for black hole, because the holographic dark energy comes from the black hole energy density. In order to derive the EOS of a black hole, we may use its dual (quantum) systems. Finally, a regular black hole without the singularity is introduced to describe an accelerating universe inside the cosmological horizon. Inspired by this, we show that the holographic energy density with the cosmological horizon as the IR cutoff leads to the dark energy-dominated universe with $\\omega_{\\rm \\Lambda}=-1$.
Quantum Black Hole Model and Hawking's Radiation
V. A. Berezin
1996-02-12T23:59:59.000Z
The black hole model with a self-gravitating charged spherical symmetric dust thin shell as a source is considered. The Schroedinger-type equation for such a model is derived. This equation appeared to be a finite differences equation. A theory of such an equation is developed and general solution is found and investigated in details. The discrete spectrum of the bound state energy levels is obtained. All the eigenvalues appeared to be infinitely degenerate. The ground state wave functions are evaluated explicitly. The quantum black hole states are selected and investigated. It is shown that the obtained black hole mass spectrum is compatible with the existence of Hawking's radiation in the limit of low temperatures both for large and nearly extreme Reissner-Nordstrom black holes. The above mentioned infinite degeneracy of the mass (energy) eigenvalues may appeared helpful in resolving the well known information paradox in the black hole physics.
Black Hole Thermodynamics Based on Unitary Evolutions
Feng, Yu-Lei
2015-01-01T23:59:59.000Z
In this paper, we try to construct black hole thermodynamics based on the fact that, the formation and evaporation of a black hole can be described by quantum unitary evolutions. First, we show that the Bekenstein-Hawking entropy $S_{BH}$ cannot be a Boltzmann or thermal entropy. To confirm this statement, we show that the original black hole's "first law" cannot be treated as the first law of thermodynamics formally, due to some missing metric perturbations caused by matter. Then, by including those (quantum) metric perturbations, we show that the black hole formation and evaporation can be described in a unitary manner effectively, through a quantum channel between the exterior and interior of the event horizon. In this way, the paradoxes of information loss and firewall can be resolved effectively. Finally, we show that black hole thermodynamics can be constructed in an ordinary way, by constructing statistical mechanics.
Fourier Analysis of the BTZ Black Hole
Ian M. Tolfree
2009-11-11T23:59:59.000Z
In this paper we extend our previous work regarding the role of the Fourier transformation in bulk to boundary mappings to include the BTZ black hole. We follow standard procedures for modifying Fourier Transformations to accommodate quotient spaces and arrive at a bulk to boundary mapping in a black hole background. We show that this mapping is consistent with known results and lends a new insight into the AdS/CFT duality. We find that the micro-states corresponding to the entropy of a bulk scalar field are the Fourier coefficients on the boundary, which transform under the principal series representation of $SL(2,R)$. Building upon this we present a toy model to analyze the implications of this for the origin of black hole entropy. We find that the black hole micro-states live on the boundary and correspond to the possible emission modes of the black hole
An electromagnetic black hole made of metamaterials
Cheng, Qiang
2009-01-01T23:59:59.000Z
Traditionally, a black hole is a region of space with huge gravitational field in the means of general relativity, which absorbs everything hitting it including the light. In general relativity, the presence of matter-energy densities results in the motion of matter propagating in a curved spacetime1, which is similar to the electromagnetic-wave propagation in a curved space and in an inhomogeneous metamaterial2. Hence one can simulate the black hole using electromagnetic fields and metamaterials. In a recent theoretical work, an optical black hole has been proposed based on metamaterials, in which the numerical simulations showed a highly efficient light absorption3. Here we report the first experimental demonstration of electromagnetic black hole in the microwave frequencies. The proposed black hole is composed of non-resonant and resonant metamaterial structures, which can absorb electromagnetic waves efficiently coming from all directions due to the local control of electromagnetic fields. Hence the elect...
Fermionic greybody factors in dilaton black holes
Jahed Abedi; Hessamaddin Arfaei
2014-09-17T23:59:59.000Z
In this paper the question of emission of fermions in the process of dilaton black hole evolution and its characters for different dilaton coupling constants $\\alpha$ is studied. The main quantity of interest, the greybody factors are calculated both numerically and in analytical approximation. The dependence of rates of evaporation and behaviour on the dilaton coupling constant is analyzed. Having calculated the greybody factors we are able to address the question of the final fate of the dilaton black hole. For that we also need to make dynamical treatment of the solution by considering the backreaction which will show a crucial effect on the final result. We find a transition line in $(Q/M, \\alpha)$ plane that separates the two regimes for the fate of the black hole, decay regime and extremal regime. In the decay regime the black hole completely evaporates, while in the extremal regime the black hole approaches the extremal limit by radiation and becomes stable.
Black holes in Asymptotically Safe Gravity
Saueressig, Frank; D'Odorico, Giulio; Vidotto, Francesca
2015-01-01T23:59:59.000Z
Black holes are among the most fascinating objects populating our universe. Their characteristic features, encompassing spacetime singularities, event horizons, and black hole thermodynamics, provide a rich testing ground for quantum gravity ideas. In this note we observe that the renormalization group improved Schwarzschild black holes constructed by Bonanno and Reuter within Weinberg's asymptotic safety program constitute a prototypical example of a Hayward geometry used to model non-singular black holes within quantum gravity phenomenology. Moreover, they share many features of a Planck star: their effective geometry naturally incorporates the one-loop corrections found in the effective field theory framework, their Kretschmann scalar is bounded, and the black hole singularity is replaced by a regular de Sitter patch. The role of the cosmological constant in the renormalization group improvement process is briefly discussed.
The balance of power: accretion and feedback in stellar mass black holes
Fender, Rob
2015-01-01T23:59:59.000Z
In this review we discuss the population of stellar-mass black holes in our galaxy and beyond, which are the extreme endpoints of massive star evolution. In particular we focus on how we can attempt to balance the available accretion energy with feedback to the environment via radiation, jets and winds, considering also possible contributions to the energy balance from black hole spin and advection. We review quantitatively the methods which are used to estimate these quantities, regardless of the details of the astrophysics close to the black hole. Once these methods have been outlined, we work through an outburst of a black hole X-ray binary system, estimating the flow of mass and energy through the different accretion rates and states. While we focus on feedback from stellar mass black holes in X-ray binary systems, we also consider the applicability of what we have learned to supermassive black holes in active galactic nuclei. As an important control sample we also review the coupling between accretion an...
Gravitational waves versus black holes
Trevor W. Marshall
2007-07-02T23:59:59.000Z
It is argued that, in order for the gravitational field to be propagated as a wave, it is necessary for it to satisfy a further set of field equations, in addition to those of Einstein and Hilbert, and these equations mean there is a preferred coordinate frame, called the Global Inertial Frame, giving rise to a unique metric . The implication is that a true gravitational field is not compatible with Einstein's Principle of Equivalence, which is in contradiction with his other fundamental concept of locality. The additional field equations ensure that gravitational collapse does not go below the Schwarzschild radius, thereby excluding the possibility of singular solutions (black holes) of the Einstein-Hilbert equations. Such solutions would also violate Einstein's locality principle.
Krotov, D. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect 7a, Moscow 117312 (Russian Federation); Moscow State University, Department of Physics, Vorobjevy Gory, Moscow, 119899 (Russian Federation); Institute of Theoretical and Experimental Physics, B. Cheremushkinskaya, 25, Moscow, 117259 (Russian Federation); Rebbi, C. [Department of Physics, Boston University, 590 Commonwealth Avenue, Boston Massachusetts 02215 (United States); Rubakov, V. [Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary prospect 7a, Moscow 117312 (Russian Federation); Zakharov, V. [Max-Planck Institut fuer Physik, Foeringer Ring 6, 80805, Munichn (Germany)
2005-02-15T23:59:59.000Z
In a recently proposed model of 'ghost condensation', spatially homogeneous states may mix, via tunneling, with inhomogeneous states which are somewhat similar to bubbles in the theory of false vacuum decay, the corresponding bubble nucleation rate being exponentially sensitive to the ultraviolet completion of the model. The conservation of energy and charge requires that the energy density is negative and the field is strongly unstable in a part of the nucleated bubble. Unlike in the theory of false vacuum decay, this region does not expand during subsequent real-time evolution. In the outer part, positive energy outgoing waves develop, which eventually form shocks. Behind the outgoing waves and away from the bubble center, the background settles down to its original value. The outcome of the entire process is thus a microscopic region of negative energy and strong field - 'hole in the ghost condensate' - plus a collection of outgoing waves (particles of the ghost condensate field) carrying away finite energy.
Thermodynamics of Dyonic Lifshitz Black Holes
Tobias Zingg
2011-07-15T23:59:59.000Z
Black holes with asymptotic anisotropic scaling are conjectured to be gravity duals of condensed matter system close to quantum critical points with non-trivial dynamical exponent z at finite temperature. A holographic renormalization procedure is presented that allows thermodynamic potentials to be defined for objects with both electric and magnetic charge in such a way that standard thermodynamic relations hold. Black holes in asymptotic Lifshitz spacetimes can exhibit paramagnetic behavior at low temperature limit for certain values of the critical exponent z, whereas the behavior of AdS black holes is always diamagnetic.
Some remarks on black hole thermodynamics
R. Y. Chiao
2011-02-04T23:59:59.000Z
Two thermodynamic "paradoxes" of black hole physics are re-examined. The first is that there is a thermal instability involving two coupled blackbody cavities containing two black holes, and second is that a classical black hole can swallow up entropy in the form of ambient blackbody photons without increasing its mass. The resolution of the second paradox by Bekenstein and by Hawking is re-visited. The link between Hawking radiation and Wigner's superluminal tunneling time is discussed using two equivalent Feynman diagrams, and Feynman's re-interpretation principle.
Black hole hair in higher dimensions
Chao Cao; Yi-Xin Chen; Jian-Long Li
2008-04-02T23:59:59.000Z
We study the property of matter in equilibrium with a static, spherically symmetric black hole in D-dimensional spacetime. It requires this kind of matter has an equation of state (\\omega\\equiv p_r/\\rho=-1/(1+2kn), k,n\\in \\mathbb{N}), which seems to be independent of D. However, when we associate this with specific models, some interesting limits on space could be found: (i)(D=2+2kn) while the black hole is surrounded by cosmic strings; (ii)the black hole can be surrounded by linear dilaton field only in 4-dimensional spacetime. In both cases, D=4 is special.
Radion clouds around evaporating black holes
J. R. Morris
2009-09-03T23:59:59.000Z
A Kaluza-Klein model, with a matter source associated with Hawking radiation from an evaporating black hole, is used to obtain a simple form for the radion effective potential. The environmental effect generally causes a matter-induced shift of the radion vacuum, resulting in the formation of a radion cloud around the hole. There is an albedo due to the radion cloud, with an energy dependent reflection coefficient that depends upon the size of the extra dimensions and the temperature of the hole.
Podgornik, Rudolf
Electrical Conduction in Native Deoxyribonucleic Acid: Hole Hopping Transfer Mechanism? Zdravko with the activation energy of 0:9 eV; however, based on the quality of the fits, the hopping ansatz cannot be ruled, and for possible applications in nanoelec- tronic circuit technology [2,5,6]. However, despite inten- sive
Thermodynamics of Schwarzschild-de Sitter black hole: thermal stability of Nariai black hole
Yun Soo Myung
2008-03-28T23:59:59.000Z
We study thermodynamics of the Schwarzschild-de Sitter black hole in five dimensions by introducing two temperatures based on the standard and Bousso-Hawking normalizations. We use the first-law of thermodynamics to derive thermodynamic quantities. The two temperatures indicate that the Nariai black hole is thermodynamically unstable. However, it seems that black hole thermodynamics favors the standard normalization, and does not favor the Bousso-Hawking normalization.
Black hole evolution: I. Supernova-regulated black hole growth
Dubois, Yohan; Silk, Joseph; Devriendt, Julien; Slyz, Adrianne; Teyssier, Romain
2015-01-01T23:59:59.000Z
The growth of a supermassive black hole (BH) is determined by how much gas the host galaxy is able to feed it, which in turn is controlled by the cosmic environment, through galaxy mergers and accretion of cosmic flows that time how galaxies obtain their gas, but also by internal processes in the galaxy, such as star formation and feedback from stars and the BH itself. In this paper, we study the growth of a 10^12 Msun halo at z=2, which is the progenitor of an archetypical group of galaxies at z=0, and of its central BH by means of a high-resolution zoomed cosmological simulation, the Seth simulation. We study the evolution of the BH driven by the accretion of cold gas in the galaxy, and explore the efficiency of the feedback from supernovae (SNe). For a relatively inefficient energy input from SNe, the BH grows at the Eddington rate from early times, and reaches self-regulation once it is massive enough. We find that at early cosmic times z>3.5, efficient feedback from SNe forbids the formation of a settled...
Tucker Wireline Open Hole Wireline Logging
Milliken, M.
2002-05-23T23:59:59.000Z
The Tucker Wireline unit ran a suite of open hole logs right behind the RMOTC logging contractor for comparison purposes. The tools included Dual Laterolog, Phased Induction, BHC Sonic, and Density-Porosity.
Towards Black Hole Entropy in Shape Dynamics
Gabriel Herczeg; Vasudev Shyam
2014-10-21T23:59:59.000Z
Shape dynamics is classical theory of gravity which agrees with general relativity in many important cases, but possesses different gauge symmetries and constraints. Rather than spacetime diffeomorphism invariance, shape dynamics takes spatial diffeomorphism invariance and spatial Weyl invariance as the fundamental gauge symmetries associated with the gravitational field. Since the area of the event horizon of a black hole transforms under a generic spatial Weyl transformation, there has been some doubt that one can speak sensibly about the thermodynamics of black holes in shape dynamics. The purpose of this paper is to show that by treating the event horizon of a black hole as an interior boundary, one can recover familiar notions of black hole thermodynamics in shape dynamics and define a gauge invariant entropy that agrees with general relativity.
Multipole moments of bumpy black holes
Vigeland, Sarah Jane
General relativity predicts the existence of black holes, compact objects whose spacetimes depend only on their mass, spin, and charge in vacuum (the “no-hair” theorem). As various observations probe deeper into the strong ...
Hole Coupling Resonator for Free Electron Lasers
Xie, M.
2011-01-01T23:59:59.000Z
3. Total round-trip power loss, coupling efficiency and themicron. Total round-trip power loss and coupling efficiencythe total fractional power loss per round trip, the hole
Black Hole Thermodynamics in Modified Gravity
Jonas R. Mureika; John W. Moffat; Mir Faizal
2015-03-03T23:59:59.000Z
We analyze the thermodynamics of a non-rotating and rotating black hole in a modified theory of gravity that includes scalar and vector modifications to general relativity, which results in a modified gravitational constant $G = G_N(1+\\alpha)$ and a new gravitational charge $Q = \\sqrt{\\alpha G_N}M$. The influence of the parameter $\\alpha$ alters the non-rotating black hole's lifetime, temperature and entropy profiles from the standard Schwarzschild case. The thermodynamics of a rotating black hole is analyzed and it is shown to possess stable, cold remnants. The thermodynamic properties of a vacuum solution regular at $r=0$ are investigated and the solution without a horizon called a "gray hole" is not expected to possess an information loss problem.
Energy of 4-Dimensional Black Hole, etc
Dmitriy Palatnik
2011-07-18T23:59:59.000Z
In this letter I suggest possible redefinition of mass density, not depending on speed of the mass element, which leads to a more simple stress-energy for an object. I calculate energy of black hole.
Anosov maps with rectangular holes. Nonergodic cases.
Ingenier'ia. Universidad de la Rep'ublica C.C. 30, Montevideo, Uruguay EÂmail: roma@fing.edu.uy; Fax: (598 Partially supported by CONICYT (Uruguay). 1 #12; Running head: Anosov maps with rectangular holes Address
Horizon Operator Approach to Black Hole Quantization
G. 't Hooft
1994-02-21T23:59:59.000Z
The $S$-matrix Ansatz for the construction of a quantum theory of black holes is further exploited. We first note that treating the metric tensor $g_{\\m\
Topological Black Holes -- Outside Looking In
R. B. Mann
1997-09-15T23:59:59.000Z
I describe the general mathematical construction and physical picture of topological black holes, which are black holes whose event horizons are surfaces of non-trivial topology. The construction is carried out in an arbitrary number of dimensions, and includes all known special cases which have appeared before in the literature. I describe the basic features of massive charged topological black holes in $(3+1)$ dimensions, from both an exterior and interior point of view. To investigate their interiors, it is necessary to understand the radiative falloff behaviour of a given massless field at late times in the background of a topological black hole. I describe the results of a numerical investigation of such behaviour for a conformally coupled scalar field. Significant differences emerge between spherical and higher genus topologies.
Spacetime constraints on accreting black holes
Garofalo, David [Jet Propulsion Laboratory, California Institute of Technology, Pasadena California 91109 (United States)
2009-06-15T23:59:59.000Z
We study the spin dependence of accretion onto rotating Kerr black holes using analytic techniques. In its linear regime, angular momentum transport in MHD turbulent accretion flow involves the generation of radial magnetic field connecting plasma in a differentially rotating flow. We take a first principles approach, highlighting the constraint that limits the generation and amplification of radial magnetic fields, stemming from the transfer of energy from mechanical to magnetic form. Because the energy transferred in magnetic form is ultimately constrained by gravitational potential energy or Killing energy, the spin dependence of the latter allows us to derive spin-dependent constraints on the success of the accreting plasma to expel its angular momentum. We find an inverse relationship between this ability and black hole spin. If this radial magnetic field generation forms the basis for angular momentum transfer in accretion flows, accretion rates involving Kerr black holes are expected to be lower as the black hole spin increases in the prograde sense.
Scattering map for two black holes
Alessandro P. S. de Moura; Patricio S. Letelier
1999-10-25T23:59:59.000Z
We study the motion of light in the gravitational field of two Schwarzschild black holes, making the approximation that they are far apart, so that the motion of light rays in the neighborhood of one black hole can be considered to be the result of the action of each black hole separately. Using this approximation, the dynamics is reduced to a 2-dimensional map, which we study both numerically and analytically. The map is found to be chaotic, with a fractal basin boundary separating the possible outcomes of the orbits (escape or falling into one of the black holes). In the limit of large separation distances, the basin boundary becomes a self-similar Cantor set, and we find that the box-counting dimension decays slowly with the separation distance, following a logarithmic decay law.
Radioactive hot cell access hole decontamination machine
Simpson, William E. (Richland, WA)
1982-01-01T23:59:59.000Z
Radioactive hot cell access hole decontamination machine. A mobile housing has an opening large enough to encircle the access hole and has a shielding door, with a door opening and closing mechanism, for uncovering and covering the opening. The housing contains a shaft which has an apparatus for rotating the shaft and a device for independently translating the shaft from the housing through the opening and access hole into the hot cell chamber. A properly sized cylindrical pig containing wire brushes and cloth or other disks, with an arrangement for releasably attaching it to the end of the shaft, circumferentially cleans the access hole wall of radioactive contamination and thereafter detaches from the shaft to fall into the hot cell chamber.
Thermodynamics and evaporation of the noncommutative black hole
Yun Soo Myung; Yong-Wan Kim; Young-Jai Park
2007-01-21T23:59:59.000Z
We investigate the thermodynamics of the noncommutative black hole whose static picture is similar to that of the nonsingular black hole known as the de Sitter-Schwarzschild black hole. It turns out that the final remnant of extremal black hole is a thermodynamically stable object. We describe the evaporation process of this black hole by using the noncommutativity-corrected Vaidya metric. It is found that there exists a close relationship between thermodynamic approach and evaporation process.
Spacetime noncommutative effect on black hole as particle accelerators
Chikun Ding; Changqing Liu; Qian Guo
2013-01-08T23:59:59.000Z
We study the spacetime noncommutative effect on black hole as particle accelerators and, find that particle falling from infinity with zero velocity cannot collide with unbound energy when the noncommutative Kerr black hole is exactly extremal. Our results also show that the bigger of the spinning black hole's mass is, the higher of center of mass energy that the particles obtain. For small and medium noncommutative Schwarzschild black hole, the collision energy depends on the black holes' mass.
Light curve of a source orbiting around a black hole: A fitting-formula
V. Karas
1996-05-15T23:59:59.000Z
A simple, analytical fitting-formula for a photometric light curve of a source of light orbiting around a black hole is presented. The formula is applicable for sources on a circular orbit with radius smaller than 45 gravitational radii from the black hole. This range of radii requires gravitational focusation of light rays and the Doppler effect to be taken into account with care. The fitting-formula is therefore useful for modelling the X-ray variability of inner regions in active galactic nuclei.
Comment on "Black holes constrain varying constants"
V. V. Flambaum
2002-08-20T23:59:59.000Z
A recent paper [DDL] claims that the increase of the proton electric charge e leads to a (forbidden) decrease of black hole entropy, therefore, possible evidence for variation of $\\alpha=e^2/\\hbar c$ [alpha] must be interpreted as a decrease of the speed of light. We argue that purely theoretical consideration of black holes possibly cannot give any model-independent limitations on variation of fundamental constants.
Fractionated Branes and Black Hole Interiors
Martinec, Emil J
2015-01-01T23:59:59.000Z
Combining a variety of results in string theory and general relativity, a picture of the black hole interior is developed wherein spacetime caps off at an inner horizon, and the inter-horizon region is occupied by a Hagedorn gas of a very low tension state of fractionated branes. This picture leads to natural resolutions of a variety of puzzles concerning quantum black holes. Gravity Research Foundation 2015 Fourth Prize Award for Essays on Gravitation.
Fractionated Branes and Black Hole Interiors
Emil J. Martinec
2015-05-20T23:59:59.000Z
Combining a variety of results in string theory and general relativity, a picture of the black hole interior is developed wherein spacetime caps off at an inner horizon, and the inter-horizon region is occupied by a Hagedorn gas of a very low tension state of fractionated branes. This picture leads to natural resolutions of a variety of puzzles concerning quantum black holes. Gravity Research Foundation 2015 Fourth Prize Award for Essays on Gravitation.
Local temperature for dynamical black holes
Sean A. Hayward; R. Di Criscienzo; M. Nadalini; L. Vanzo; S. Zerbini
2008-12-13T23:59:59.000Z
A local Hawking temperature was recently derived for any future outer trapping horizon in spherical symmetry, using a Hamilton-Jacobi tunneling method, and is given by a dynamical surface gravity as defined geometrically. Descriptions are given of the operational meaning of the temperature, in terms of what observers measure, and its relation to the usual Hawking temperature for static black holes. Implications for the final fate of an evaporating black hole are discussed.
Notes on Black Hole Fluctuations and Backreaction
B. L. Hu; Alpan Raval; Sukanya Sinha
1999-01-05T23:59:59.000Z
In these notes we prepare the ground for a systematic investigation into the issues of black hole fluctuations and backreaction by discussing the formulation of the problem, commenting on possible advantages and shortcomings of existing works, and introducing our own approach via a stochastic semiclassical theory of gravity based on the Einstein-Langevin equation and the fluctuation-dissipation relation for a self-consistent description of metric fluctuations and dissipative dynamics of the black hole with backreaction of its Hawking radiance.
The obscuration by dust of most of the growth of supermassive black holes
Alejo Martinez-Sansigre; Steve Rawlings; Mark Lacy; Dario Fadda; Francine R. Marleau; Chris Simpson; Chris J. Willott; Matt J. Jarvis
2005-07-29T23:59:59.000Z
Supermassive black holes underwent periods of exponential growth during which we seem them as quasars in the distant Universe. The summed emission from these quasars generates the cosmic X-ray background, the spectrum of which has been used to argue that most black-hole growth is obscured. There are clear examples of obscured black-hole growth in the form of `type-2' quasars, but their numbers are fewer than expected from modelling of the X-ray background. Here we report on the direct detection of a population of distant type-2 quasars which is at least comparable in size to the well-known unobscured type-1 population. We selected objects that have mid-infrared and radio emissions characteristic of quasars, but which are faint at near-infrared and optical wavelengths. This population is responsible for most of the black hole growth in the young Universe and, throughout cosmic history, black-hole growth occurs in the dusty, gas-rich centres of active galaxies.
Black holes at the centers of nearby dwarf galaxies
Moran, Edward C.; Shahinyan, Karlen; Sugarman, Hannah R.; Vélez, Darik O. [Astronomy Department, Wesleyan University, Middletown, CT 06459 (United States); Eracleous, Michael [Department of Astronomy and Astrophysics, and Institute for Gravitation and the Cosmos, The Pennsylvania State University, 525 Davey Lab, University Park, PA 16802 (United States)
2014-12-01T23:59:59.000Z
Using a distance-limited portion of the Sloan Digital Sky Survey (SDSS) Data Release 7, we have identified 28 active galactic nuclei (AGNs) in nearby (d?80 Mpc) low-mass, low-luminosity dwarf galaxies. The accreting objects at the galaxy centers are expected to be intermediate-mass black holes (IMBHs) with M{sub BH}?10{sup 6} M{sub ?}. The AGNs were selected using several optical emission-line diagnostics after careful modeling of the continuum present in the spectra. We have limited our survey to objects with spectral characteristics similar to those of Seyfert nuclei, excluding emission-line galaxies with ambiguous spectra that could be powered by stellar processes. Thus, as a set, the host galaxies in our sample are the least massive objects in the very local universe certain to contain central black holes. Our sample is dominated by narrow-line (type 2) AGNs, and it appears to have a much lower fraction of broad-line objects than that observed for luminous, optically selected Seyfert galaxies. Given our focus on the nearest objects included in the SDSS, our survey is more sensitive to low-luminosity emission than previous optical searches for AGNs in low-mass galaxies. The [O iii] ?5007 luminosities of the Seyfert nuclei in our sample have a median value of L{sub 5007}=2×10{sup 5} L{sub ?} and extend down to ?10{sup 4} L{sub ?}. Using published data for broad-line IMBH candidates, we have derived an [O iii] bolometric correction of log(L{sub bol}/L{sub 5007})=3.0±0.3, which is significantly lower than values obtained for high-luminosity AGNs. Applying this correction to our sample, we obtain minimum black hole mass estimates that fall mainly in the 10{sup 3} M{sub ?}–10{sup 4} M{sub ?} range, which is roughly where the predicted mass functions for different black hole seed formation scenarios overlap the most. In the stellar mass range that includes the bulk of the AGN host galaxies in our sample, we derive a lower limit on the AGN fraction of a few percent, indicating that active nuclei in dwarf galaxies are not as rare as previously thought.
The Revival of White Holes as Small Bangs
Alon Retter; Shlomo Heller
2011-07-17T23:59:59.000Z
Black holes are extremely dense and compact objects from which light cannot escape. There is an overall consensus that black holes exist and many astronomical objects are identified with black holes. White holes were understood as the exact time reversal of black holes, therefore they should continuously throw away material. It is accepted, however, that a persistent ejection of mass leads to gravitational pressure, the formation of a black hole and thus to the "death of while holes". So far, no astronomical source has been successfully tagged a white hole. The only known white hole is the Big Bang which was instantaneous rather than continuous or long-lasting. We thus suggest that the emergence of a white hole, which we name a 'Small Bang', is spontaneous - all the matter is ejected at a single pulse. Unlike black holes, white holes cannot be continuously observed rather their effect can only be detected around the event itself. Gamma ray bursts are the most energetic explosions in the universe. Long gamma-ray bursts were connected with supernova eruptions. There is a new group of gamma-ray bursts, which are relatively close to Earth, but surprisingly lack any supernova emission. We propose identifying these bursts with white holes. White holes seem like the best explanation of gamma-ray bursts that appear in voids. We also predict the detection of rare gigantic gamma-ray bursts with energies much higher than typically observed.
Holographic superconductor in the exact hairy black hole
Yun Soo Myung; Chanyong Park
2011-09-13T23:59:59.000Z
We study the charged black hole of hyperbolic horizon with scalar hair (charged Martinez-Troncoso-Zanelli: CMTZ black hole) as a model of analytic hairy black hole for holographic superconductor. For this purpose, we investigate the second order phase transition between CMTZ and hyperbolic Reissner-Nordstr\\"om-AdS (HRNAdS) black holes. However, this transition unlikely occur. As an analytic treatment for holographic superconductor, we develop superconductor in the bulk and superfluidity on the boundary using the CMTZ black hole below the critical temperature. The presence of charge destroys the condensates around the zero temperature, which is in accord with the thermodynamic analysis of the CMTZ black hole.
The Environmental Impact of Supermassive Black Holes
Abraham Loeb
2004-08-10T23:59:59.000Z
The supermassive black holes observed at the centers of almost all present-day galaxies, had a profound impact on their environment. I highlight the principle of self-regulation, by which supermassive black holes grow until they release sufficient energy to unbind the gas that feeds them from their host galaxy. This principle explains several observed facts, including the correlation between the mass of a central black hole and the depth of the gravitational potential well of its host galaxy, and the abundance and clustering properties of bright quasars in the redshift interval of z~2-6. At lower redshifts, quasars might have limited the maximum mass of galaxies through the suppression of cooling flows in X-ray clusters. The seeds of supermassive black holes were likely planted in dwarf galaxies at redshifts z>10, through the collapse of massive or supermassive stars. The minimum seed mass can be identified observationally through the detection of gravitational waves from black hole binaries by Advanced LIGO or LISA. Aside from shaping their host galaxies, quasar outflows filled the intergalactic medium with magnetic fields and heavy elements. Beyond the reach of these outflows, the brightest quasars at z>6 have ionized exceedingly large volumes of gas (tens of comoving Mpc) prior to global reionization, and must have suppressed the faint end of the galaxy luminosity function in these volumes before the same occurred through the rest of the universe.
Perturbative String Thermodynamics near Black Hole Horizons
Thomas G. Mertens; Henri Verschelde; Valentin I. Zakharov
2014-10-29T23:59:59.000Z
We provide further computations and ideas to the problem of near-Hagedorn string thermodynamics near (uncharged) black hole horizons, building upon our earlier work JHEP 1403 (2014) 086. The relevance of long strings to one-loop black hole thermodynamics is emphasized. We then provide an argument in favor of the absence of $\\alpha'$-corrections for the (quadratic) heterotic thermal scalar action in Rindler space. We also compute the large $k$ limit of the cigar orbifold partition functions (for both bosonic and type II superstrings) which allows a better comparison between the flat cones and the cigar cones. A discussion is made on the general McClain-Roth-O'Brien-Tan theorem and on the fact that different torus embeddings lead to different aspects of string thermodynamics. The black hole/string correspondence principle for the 2d black hole is discussed in terms of the thermal scalar. Finally, we present an argument to deal with arbitrary higher genus partition functions, suggesting the breakdown of string perturbation theory (in $g_s$) to compute thermodynamical quantities in black hole spacetimes.
Investigating Dark Energy with Black Hole Binaries
Laura Mersini-Houghton; Adam Kelleher
2009-06-08T23:59:59.000Z
The accelerated expansion of the universe is ascribed to the existence of dark energy. Black holes accretion of dark energy induces a mass change proportional to the energy density and pressure of the background dark energy fluid. The time scale during which the mass of black holes changes considerably is too long relative to the age of the universe, thus beyond detection possibilities. We propose to take advantage of the modified black hole masses for exploring the equation of state $w[z]$ of dark energy, by investigating the evolution of supermassive black hole binaries on a dark energy background. Deriving the signatures of dark energy accretion on the evolution of binaries, we find that dark energy imprints on the emitted gravitational radiation and on the changes in the orbital radius of the binary can be within detection limits for certain supermassive black hole binaries. In this talk I describe how binaries can provide a useful tool in obtaining complementary information on the nature of dark energy, based on the work done with A.Kelleher.
Black Holes with Flavors of Quantum Hair?
Gia Dvali
2006-07-20T23:59:59.000Z
We show that black holes can posses a long-range quantum hair of super-massive tensor fields, which can be detected by Aharonov-Bohm tabletop interference experiments, in which a quantum-hairy black hole, or a remnant particle, passes through the loop of a magnetic solenoid. The long distance effect does not decouple for an arbitrarily high mass of the hair-providing field. Because Kaluza-Klein and String theories contain infinite number of massive tensor fields, we study black holes with quantum Kaluza-Klein hair. We show that in five dimensions such a black hole can be interpreted as a string of `combed' generalized magnetic monopoles, with their fluxes confined along it. For the compactification on a translation-invariant circle, this substructure uncovers hidden flux conservation and quantization of the monopole charges, which constrain the quantum hair of the resulting four-dimensional black hole. For the spin-2 quantum hair this result is somewhat unexpected, since the constituent `magnetic' charges have no `electric' counterparts. Nevertheless, the information about their quantization is encoded in singularity.
Black Hole Chromosphere at the LHC
Luis Anchordoqui; Haim Goldberg
2003-02-26T23:59:59.000Z
If the scale of quantum gravity is near a TeV, black holes will be copiously produced at the LHC. In this work we study the main properties of the light descendants of these black holes. We show that the emitted partons are closely spaced outside the horizon, and hence they do not fragment into hadrons in vacuum but more likely into a kind of quark-gluon plasma. Consequently, the thermal emission occurs far from the horizon, at a temperature characteristic of the QCD scale. We analyze the energy spectrum of the particles emerging from the "chromosphere", and find that the hard hadronic jets are almost entirely suppressed. They are replaced by an isotropic distribution of soft photons and hadrons, with hundreds of particles in the GeV range. This provides a new distinctive signature for black hole events at LHC.
Hole interactions with molecular vibrations on DNA
A. Omerzu; M. Licer; T. Mertelj; V. V. Kabanov; D. Mihailovic
2004-05-13T23:59:59.000Z
We report on a study of the interactions between holes and molecular vibrations on dry DNA using photoinduced infrared absorption spectroscopy. Laser photoexcited (PE) holes are found to have a room-temperature lifetime in excess of 1 ms, clearly indicating the presence of localization. However, from a quantitative model analysis of the frequency shifts of vibrational modes caused by the PE holes, we find the holevibrational coupling constant to be relatively small, 0.2. This interaction leads to a change in the conformational energy of 0.015 eV, which is too small to cause selftrapping at room temperature. We conclude that, at least in the dry (A) form, DNA is best understood in terms of a double chain of coupled quantum dots arising from the pseudo-random chain sequence of base pairs, in which Anderson localization prevents the formation of a metallic state.
Neutrino Majorana Mass from Black Hole
Yosuke Uehara
2002-05-25T23:59:59.000Z
We propose a new mechanism to generate the neutrino Majorana mass in TeV-scale gravity models. The black hole violates all non-gauged symmetries and can become the origin of lepton number violating processes. The fluctuation of higher-dimensional spacetime can result in the production of a black hole, which emits 2 neutrinos. If neutrinos are Majorana particles, this process is equivalent to the free propagation of a neutrino with the insertion of the black hole. From this fact, we derive the neutrino Majorana mass. The result is completely consistent with the recently observed evidence of neutrinoless double beta decay. And the obtained neutrino Majorana mass satisfies the constraint from the density of the neutrino dark matter, which affects the cosmic structure formation. Furthermore, we can explain the ultrahigh energy cosmic rays by the Z-burst scenario with it.
Particle-hole symmetry parameters for nuclei
Ian Bentley
2015-03-10T23:59:59.000Z
Two parameters, nu and zeta, motivated by particle-hole symmetry are introduced. These parameters are determined using the number of proton (or neutron) particles and holes counted from neighboring shell closures. The new parameters can be used to evaluate particle-hole and proton-neutron symmetries of adopted B(E2) values, which indicate that both symmetries are approximate for A>100. The combined symmetries motivate empirical fits of binding energies and the energy ratio E(4_1^+)/E(2_1^+). A global binding energy fit consisting of a traditional liquid droplet and one new shell term, comprised of a function of nu and zeta, reproduces the experimental binding energies of 2353 nuclei with an r.m.s. standard deviation of 1.55 MeV.
Turbodrilling in the hot-hole environment
Herbert, P.
1982-10-01T23:59:59.000Z
Historically, geothermal and other types of hot-hole drilling have presented what seemed to be insurmountable barriers to efficient and extended use of downhole drilling motors, particularly those containing elastomeric bearing or motor components. Typical temperatures of 350 to 700/sup 0/F (177 to 371/sup 0/C) damage the elastomers and create other operating problems, reducing the life of the motors and their ability to drill efficiently. Recent innovations in turbodrill design have opened heretofore unrealized potentials and have allowed, for the first time, extended downhole drilling time in hot-hole conditions. The unique feature of this turbodrill is the lack of any elastomers or other temperature-sensitive materials. Its capabilities are matched closely to the requirements of drilling in elevated-temperature environments. The bearing assembly can withstand conditions encountered in typical geothermal formations and provides the performance necessary to stay in the hole. The result is increased rate of penetration (ROP) and more economical drilling.
Structure of the Spherical Black Hole Interior
A. Bonanno; S. Droz; W. Israel; S. M. Morsink
1994-11-18T23:59:59.000Z
The internal structure of a charged spherical black hole is still a topic of debate. In a nonrotating but aspherical gravitational collapse to form a spherical charged black hole, the backscattered gravitational wave tails enter the black hole and are blueshifted at the Cauchy horizon. This has a catastrophic effect if combined with an outflux crossing the Cauchy horizon: a singularity develops at the Cauchy horizon and the effective mass inflates. Recently a numerical study of a massless scalar field in the \\RN background suggested that a spacelike singularity may form before the Cauchy horizon forms. We will show that there exists an approximate analytic solution of the scalar field equations which allows the mass inflation singularity at the Cauchy horizon to exist. In particular, we see no evidence that the Cauchy horizon is preceded by a spacelike singularity.
Gravitational energy of rotating black holes
J. W. Maluf; E. F. Martins; A. Kneip
1996-08-21T23:59:59.000Z
In the teleparallel equivalent of general relativity the energy density of asymptotically flat gravitational fields can be naturaly defined as a scalar density restricted to a three-dimensional spacelike hypersurface $\\Sigma$. Integration over the whole $\\Sigma$ yields the standard ADM energy. After establishing the reference space with zero gravitational energy we obtain the expression of the localized energy for a Kerr black hole. The expression of the energy inside a surface of constant radius can be explicitly calculated in the limit of small $a$, the specific angular momentum. Such expression turns out to be exactly the same as the one obtained by means of the method preposed recently by Brown and York. We also calculate the energy contained within the outer horizon of the black hole for {\\it any} value of $a$. The result is practically indistinguishable from $E=2M_{ir}$, where $M_{ir}$ is the irreducible mass of the black hole.
Vacuum polarization for lukewarm black holes
Elizabeth Winstanley; Phil M. Young
2007-12-20T23:59:59.000Z
We compute the renormalized expectation value of the square of a quantum scalar field on a Reissner-Nordstrom-de Sitter black hole in which the temperatures of the event and cosmological horizons are equal (`lukewarm' black hole). Our numerical calculations for a thermal state at the same temperature as the two horizons indicate that this renormalized expectation value is regular on both the event and cosmological horizons. We are able to show analytically, using an approximation for the field modes near the horizons, that this is indeed the case.
Vacuum polarization for lukewarm black holes
Winstanley, Elizabeth; Young, Phil M. [Department of Applied Mathematics, The University of Sheffield, Hicks Building, Hounsfield Road, Sheffield, S3 7RH (United Kingdom)
2008-01-15T23:59:59.000Z
We compute the renormalized expectation value of the square of a quantum scalar field on a Reissner-Nordstroem-de Sitter black hole in which the temperatures of the event and cosmological horizons are equal ('lukewarm' black hole). Our numerical calculations for a thermal state at the same temperature as the two horizons indicate that this renormalized expectation value is regular on both the event and cosmological horizons. We are able to show analytically, using an approximation for the field modes near the horizons, that this is indeed the case.
Tachyon Perturbation on Two Dimensional Black Hole
Aniket Basu
2014-07-03T23:59:59.000Z
We study the black hole geometry in the presence of tachyonic perturbations, and solve for the form of allowed tachyonic hair in the presence of back reaction, and for the form of the metric under the assumption that only the metric is perturbed but not the dilaton. We evaluate the Kretschmann scalar and argue that the horizon becomes singular in the presence of tachyons, implying that the black hole has turned into a naked singularity. A form of the allowed tachyon potential emerges as a requirement of self-consistency of our solution.
Thermal Gravitational Waves from Primordial Black Holes
C. Sivaram; Kenath Arun
2010-05-19T23:59:59.000Z
Thermal gravitational waves can be generated in various sources such as, in the cores of stars, white dwarfs and neutron stars due to the fermion collisions in the dense degenerate Fermi gas. Such high frequency thermal gravitational waves can also be produced during the collisions in a gamma ray burst or during the final stages of the evaporation of primordial black holes. Here we estimate the thermal gravitational waves from primordial black holes and estimate the integrated energy of the gravitational wave emission over the entire volume of the universe and over Hubble time. We also estimate the gravitational wave flux from gamma ray bursts and jets.
Einstein-Yang-Mills-Lorentz Black Holes
Jose A. R. Cembranos; Jorge Gigante Valcarcel
2015-01-28T23:59:59.000Z
Different black hole solutions of the coupled Einstein-Yang-Mills equations are well known from long time. They have attracted much attention from mathematicians and physicists from their discovery. In this work, we analyze black holes associated with the gauge Lorentz group. In particular, we study solutions which identify the gauge connection with the spin connection. This ansatz allows to find exact solutions to the complete system of equations. By using this procedure, we show the equivalence between the Yang-Mills-Lorentz model in curved space-time and a particular set of extended gravitational theories.
Chaotic Information Processing by Extremal Black Holes
Axenides, Minos; Nicolis, Stam
2015-01-01T23:59:59.000Z
We review an explicit regularization of the AdS$_2$/CFT$_1$ correspondence, that preserves all isometries of bulk and boundary degrees of freedom. This scheme is useful to characterize the space of the unitary evolution operators that describe the dynamics of the microstates of extremal black holes in four spacetime dimensions. Using techniques from algebraic number theory to evaluate the transition amplitudes, we remark that the regularization scheme expresses the fast quantum computation capability of black holes as well as its chaotic nature.
Dynamics of galaxy cores and supermassive black holes
David Merritt
2006-05-02T23:59:59.000Z
Recent work on the dynamical evolution of galactic nuclei containing supermassive black holes is reviewed. Topics include galaxy structural properties; collisionless and collisional equilibria; loss-cone dynamics; and dynamics of binary and multiple supermassive black holes.
Yield, variance and spatial distribution of electron–hole...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Yield, variance and spatial distribution of electron–hole pairs in CsI. Yield, variance and spatial distribution of electron–hole pairs in CsI. Abstract: A Monte Carlo...
Evaluation of Coso Geothermal Exploratory Hole No. 1 (CGEH-1...
hole with drill cuttings. The second test, on November 2, 1978, utilized a nitrogen-foam-water mixture to clean residual particles from bottom hole, following which nitrogen was...
Topological black holes in Horava-Lifshitz gravity
Cai Ronggen [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China) and Kavli Institute for Theoretical Physics China (KITPC), Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China); Cao Liming [Asia Pacific Center for Theoretical Physics, Pohang, Gyeongbuk 790-784 (Korea, Republic of); Ohta, Nobuyoshi [Department of Physics, Kinki University, Higashi-Osaka, Osaka 577-8502 (Japan)
2009-07-15T23:59:59.000Z
We find topological (charged) black holes whose horizon has an arbitrary constant scalar curvature 2k in Horava-Lifshitz theory. Without loss of generality, one may take k=1, 0, and -1. The black hole solution is asymptotically anti-de Sitter with a nonstandard asymptotic behavior. Using the Hamiltonian approach, we define a finite mass associated with the solution. We discuss the thermodynamics of the topological black holes and find that the black hole entropy has a logarithmic term in addition to an area term. We find a duality in Hawking temperature between topological black holes in Horava-Lifshitz theory and Einstein's general relativity: the temperature behaviors of black holes with k=1, 0, and -1 in Horava-Lifshitz theory are, respectively, dual to those of topological black holes with k=-1, 0, and 1 in Einstein's general relativity. The topological black holes in Horava-Lifshitz theory are thermodynamically stable.
Thermal Gradient Holes At Upper Hot Creek Ranch Area (Benoit...
planned but higher than anticipated drilling and permitting costs within a fixed budget reduced the number of holes to five. Four of the five holes drilled to depths of 300...
A Note on Black Hole Temperature and Entropy
P. R. Silva
2006-05-09T23:59:59.000Z
We propose intuitive derivations of the Hawking temperature and the Bekenstein-Hawking entropy of a Schwarzschild black hole.
Entropy of charged dilaton-axion black hole
Tanwi Ghosh; Soumitra SenGupta
2008-06-06T23:59:59.000Z
Using brick wall method the entropy of charged dilaton-axion black hole is determined for both asymptotically flat and non-flat cases. The entropy turns out to be proportional to the horizon area of the black hole confirming the Beckenstien, Hawking area-entropy formula for black holes. The leading order logarithmic corrections to the entropy are also derived for such black holes.
Can the fluctuations of a black hole be treated thermodynamically?
Kostyantyn Ropotenko
2008-03-31T23:59:59.000Z
Since the temperature of a typical Schwarzschild black hole is very low, some doubts are raised about whether the fluctuations of the black hole can be treated thermodynamically. It is shown that this is not the case: the thermodynamic fluctuations of a black hole are considerably larger than the corresponding quantum fluctuations. Moreover the ratio of the mean square thermodynamic fluctuation to the corresponding quantum fluctuation can be interpreted as a number of the effective constituents of a black hole.
Black holes in Born-Infeld extended new massive gravity
Ghodsi, Ahmad; Yekta, Davood Mahdavian [Department of Physics, Ferdowsi University of Mashhad, P.O. Box 1436, Mashhad (Iran, Islamic Republic of)
2011-05-15T23:59:59.000Z
In this paper we find different types of black holes for the Born-Infeld extended new massive gravity. Our solutions include (un)charged warped (anti-)de Sitter black holes for four and six derivative expanded action. We also look at the black holes in unexpanded Born-Infeld action. In each case we calculate the entropy, angular momentum and mass of the black holes. We also find the central charges for the conformal field theory duals.
Entropy and Area of Black Holes in Loop Quantum Gravity
I. B. Khriplovich
2002-03-31T23:59:59.000Z
Simple arguments related to the entropy of black holes strongly constrain the spectrum of the area operator for a Schwarzschild black hole in loop quantum gravity. In particular, this spectrum is fixed completely by the assumption that the black hole entropy is maximum. Within the approach discussed, one arrives in loop quantum gravity at a quantization rule with integer quantum numbers $n$ for the entropy and area of a black hole.
Active negative-index metamaterial powered by an electron beam
Shapiro, Michael
An active negative index metamaterial that derives its gain from an electron beam is introduced. The metamaterial consists of a stack of equidistant parallel metal plates perforated by a periodic array of holes shaped as ...
THE CLUSTER AND FIELD GALAXY ACTIVE GALACTIC NUCLEUS FRACTION AT
Martini, Paul
The fraction of cluster galaxies that host luminous active galactic nuclei (AGNs) is an important probe of AGN fueling processes, the cold interstellar medium at the centers of galaxies, and how tightly black holes and ...
ANCHIALINE ECOSYSTEMS Microbial hotspots in anchialine blue holes
Iliffe, Thomas M.
ANCHIALINE ECOSYSTEMS Microbial hotspots in anchialine blue holes: initial discoveries from+Business Media B.V. 2011 Abstract Inland blue holes of the Bahamas are anchialine ecosystems with distinct fresh and geomicrobiology exploration of blue holes are providing a first glimpse of the geochemistry and microbial life
Einstein Algebras and the Hole Argument JONATHAN BAIN
Aronov, Boris
1 Einstein Algebras and the Hole Argument JONATHAN BAIN Department of Humanities and Social@duke.poly.edu word count: 5498 #12;2 word count: 5498 Einstein Algebras and the Hole Argument ABSTRACT. Einstein. In particular, I suggest that a gauge-invariant interpretation of Einstein algebras that avoids the hole
MOTION OF ELECTRON-HOLE DROPS IN Ge
Westervelt, R.M.
2011-01-01T23:59:59.000Z
MOTION OF ELECTRON-HOLE DROPS IN Ge R. M. Westervelt, J. C.MOTION OF ELECTRON-HOLE DROPS IN Ge R. M. Westervelt, J. C.OF ELECTRON-HOLE DROPS IN Ge R M Westervelt, J C Culbertson
The Role of Primordial Kicks on Black Hole Merger Rates
Miroslav Micic; Tom Abel; Steinn Sigurdsson
2006-09-06T23:59:59.000Z
Primordial stars are likely to be very massive $\\geq30\\Msun$, form in isolation, and will likely leave black holes as remnants in the centers of their host dark matter halos in the mass range $10^{6}-10^{10}\\Ms$. Such early black holes, at redshifts z$\\gtsim10$, could be the seed black holes for the many supermassive black holes found in galaxies in the local universe. If they exist, their mergers with nearby supermassive black holes may be a prime signal for long wavelength gravitational wave detectors. We simulate formation of black holes in the center of high redshift dark matter halos and explore implications of initial natal kick velocities conjectured by some formation models. The central concentration of early black holes in present day galaxies is reduced if they are born even with moderate kicks of tens of km/s. The modest kicks allow the black holes to leave their parent halo, which consequently leads to dynamical friction being less effective on the lower mass black holes as compared to those still embedded in their parent halos. Therefore, merger rates may be reduced by more than an order of magnitude. Using analytical and illustrative cosmological N--body simulations we quantify the role of natal kicks of black holes formed from massive metal free stars on their merger rates with supermassive black holes in present day galaxies. Our results also apply to black holes ejected by the gravitational slingshot mechanism.
On Space-Time Singularities, Holes, and Extensions
Manchak, John
On Space-Time Singularities, Holes, and Extensions John Byron Manchak*y Here, we clarify the relationship among three space-time conditions of interest: geodesic completeness, hole. In what follows, we consider three space-time conditions of interest: geodesic completeness, hole
Remote down-hole well telemetry
Briles, Scott D. (Los Alamos, NM); Neagley, Daniel L. (Albuquerque, NM); Coates, Don M. (Santa Fe, NM); Freund, Samuel M. (Los Alamos, NM)
2004-07-20T23:59:59.000Z
The present invention includes an apparatus and method for telemetry communication with oil-well monitoring and recording instruments located in the vicinity of the bottom of gas or oil recovery pipes. Such instruments are currently monitored using electrical cabling that is inserted into the pipes; cabling has a short life in this environment, and requires periodic replacement with the concomitant, costly shutdown of the well. Modulated reflectance, a wireless communication method that does not require signal transmission power from the telemetry package will provide a long-lived and reliable way to monitor down-hole conditions. Normal wireless technology is not practical since batteries and capacitors have to frequently be replaced or recharged, again with the well being removed from service. RF energy generated above ground can also be received, converted and stored down-hole without the use of wires, for actuating down-hole valves, as one example. Although modulated reflectance reduces or eliminates the loss of energy at the sensor package because energy is not consumed, during the transmission process, additional stored extra energy down-hole is needed.
Schwarzschild black hole in dark energy background
Ngangbam Ishwarchandra; Ng. Ibohal; K. Yugindro Singh
2014-09-27T23:59:59.000Z
In this paper we present an exact solution of Einstein's field equations describing the Schwarzschild black hole in dark energy background. It is also regarded as an embedded solution that the Schwarzschild black hole is embedded into the dark energy space producing Schwarzschild-dark energy black hole. It is found that the space-time geometry of Schwarzschild-dark energy solution is non-vacuum Petrov type $D$ in the classification of space-times. We study the energy conditions (like weak, strong and dominant conditions) for the energy-momentum tensor of the Schwarzschild-dark energy solution. We also find that the energy-momentum tensor of the Schwarzschild-dark energy solution violates the strong energy condition due to the negative pressure leading to a repulsive gravitational force of the matter field in the space-time. It is shown that the time-like vector field for an observer in the Schwarzschild-dark energy space is expanding, accelerating, shearing and non-rotating. We investigate the surface gravity and the area of the horizons for the Schwarzschild-dark energy black hole.
Black hole formation in the early universe
Latif, M A; Schmidt, W; Niemeyer, J
2013-01-01T23:59:59.000Z
Supermassive black holes with up to a $\\rm 10^{9}~M_{\\odot}$ dwell in the centers of present-day galaxies, and their presence has been confirmed at z $\\geq$ 6. Their formation at such early epochs is still an enigma. Different pathways have been suggested to assemble supermassive black holes in the first billion years after the Big Bang. Direct collapse has emerged as a highly plausible scenario to form black holes as it provides seed masses of $\\rm 10^{5}-10^{6}~M_{\\odot}$. Gravitational collapse in atomic cooling haloes with virial temperatures T$_{vir} \\geq 10^{4}$~K may lead to the formation of massive seed black holes in the presence of an intense background UV flux. Turbulence plays a central role in regulating accretion and transporting angular momentum. We present here the highest resolution cosmological large-eddy simulations to date which track the evolution of high-density regions on scales of $0.25$~AU beyond the formation of the first peak, and study the impact of subgrid-scale turbulence. The pe...
Vector particles tunneling from BTZ black holes
Ge-Rui Chen; Shiwei Zhou; Yong-Chang Huang
2014-09-21T23:59:59.000Z
In this paper we investigate vector particles' Hawking radiation from a BTZ black hole. By applying the WKB approximation and the Hamilton-Jacobi Ansatz to the Proca equation, we obtain the tunneling spectrum of vector particles. The expected Hawking temperature is recovered.
Brief review on higher spin black holes
Alfredo Perez; David Tempo; Ricardo Troncoso
2014-05-12T23:59:59.000Z
We review some relevant results in the context of higher spin black holes in three-dimensional spacetimes, focusing on their asymptotic behaviour and thermodynamic properties. For simplicity, we mainly discuss the case of gravity nonminimally coupled to spin-3 fields, being nonperturbatively described by a Chern-Simons theory of two independent sl(3,R) gauge fields. Since the analysis is particularly transparent in the Hamiltonian formalism, we provide a concise discussion of their basic aspects in this context; and as a warming up exercise, we briefly analyze the asymptotic behaviour of pure gravity, as well as the BTZ black hole and its thermodynamics, exclusively in terms of gauge fields. The discussion is then extended to the case of black holes endowed with higher spin fields, briefly signaling the agreements and discrepancies found through different approaches. We conclude explaining how the puzzles become resolved once the fall off of the fields is precisely specified and extended to include chemical potentials, in a way that it is compatible with the asymptotic symmetries. Hence, the global charges become completely identified in an unambiguous way, so that different sets of asymptotic conditions turn out to contain inequivalent classes of black hole solutions being characterized by a different set of global charges.
Deep-hole drilling Fruit Flies & Zebrafish
Li, Yi
surface to purify air, employing existing technology in a new way. It is the brainchild of artistFEATURE Deep-hole drilling Fruit Flies & Zebrafish BjÃ¶rk FEATURE Academics & Industry: ResearchIScOvER mAGAZInE discover@sheffield.ac.uk Research and Innovation Services University of Sheffield New
Weighing black holes from zero to high redshift
A. Marconi; D. Axon; R. Maiolino; T. Nagao; P. Pietrini; A. Robinson; G. Torricelli
2008-09-02T23:59:59.000Z
The application of the virial theorem provides a tool to estimate supermassive black hole (BH) masses in large samples of active galactic nuclei (AGN) with broad emission lines at all redshifts and luminosities, if the broad line region (BLR) is gravitationally bound. In this paper we discuss the importance of radiation forces on BLR clouds arising from the deposition of momentum by ionizing photons. Such radiation forces counteract gravitational ones and, if not taken into account, BH masses can be severely underestimated. We provide virial relations corrected for the effect of radiation pressure and we discuss their physical meaning and application. If these corrections to virial masses, calibrated with low luminosity objects, are extrapolated to high luminosities then the BLRs of most quasars might be gravitationally unbound. The importance of radiation forces in high luminosity objects must be thoroughly investigated to assess the reliability of quasar BH masses.
Eight powers of ten: similarities in black hole accretion on all mass scales
Rob Fender; Elmar Koerding; Tomaso Belloni; Phil Uttley; Ian McHardy; Tasso Tzioumis
2007-06-26T23:59:59.000Z
In this paper we discuss the recent advances in the quantitative comparison of accretion, and the accretion:jet coupling, in accreting black holes in both X-ray binaries (where M ~ 10Msun) and Active Galactic Nuclei (10^5Msun < M < 10^9Msun). These similarities include the radiative efficiency and jet power as a function of accretion rate, which are themselves probably the origin of the `fundamental plane of black hole activity'. A second `fundamental plane' which connects mass, accretion rate and timing properties provides us with a further physical diagnostic. Patterns of radio loudness (i.e. jet production) as a function of luminosity and accretion state are shown to be similar for X-ray binaries and AGN. Finally we discuss how neutron stars are a useful control sample, and what the future may hold for this field.
The river model of black holes
Andrew J. S. Hamilton; Jason P. Lisle
2006-08-31T23:59:59.000Z
This paper presents an under-appreciated way to conceptualize stationary black holes, which we call the river model. The river model is mathematically sound, yet simple enough that the basic picture can be understood by non-experts. %that can by understood by non-experts. In the river model, space itself flows like a river through a flat background, while objects move through the river according to the rules of special relativity. In a spherical black hole, the river of space falls into the black hole at the Newtonian escape velocity, hitting the speed of light at the horizon. Inside the horizon, the river flows inward faster than light, carrying everything with it. We show that the river model works also for rotating (Kerr-Newman) black holes, though with a surprising twist. As in the spherical case, the river of space can be regarded as moving through a flat background. However, the river does not spiral inward, as one might have anticipated, but rather falls inward with no azimuthal swirl at all. Instead, the river has at each point not only a velocity but also a rotation, or twist. That is, the river has a Lorentz structure, characterized by six numbers (velocity and rotation), not just three (velocity). As an object moves through the river, it changes its velocity and rotation in response to tidal changes in the velocity and twist of the river along its path. An explicit expression is given for the river field, a six-component bivector field that encodes the velocity and twist of the river at each point, and that encapsulates all the properties of a stationary rotating black hole.
Gardner, Andy
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Improved methods for simulating nearly extremal binary black holes
Mark A. Scheel; Matthew Giesler; Daniel A. Hemberger; Geoffrey Lovelace; Kevin Kuper; Michael Boyle; Bela Szilagyi; Lawrence E. Kidder
2014-12-04T23:59:59.000Z
Astrophysical black holes could be nearly extremal (that is, rotating nearly as fast as possible); therefore, nearly extremal black holes could be among the binaries that current and future gravitational-wave observatories will detect. Predicting the gravitational waves emitted by merging black holes requires numerical-relativity simulations, but these simulations are especially challenging when one or both holes have mass $m$ and spin $S$ exceeding the Bowen-York limit of $S/m^2=0.93$. We present improved methods that enable us to simulate merging, nearly extremal black holes more robustly and more efficiently. We use these methods to simulate an unequal-mass, precessing binary black hole coalescence, where the larger black hole has $S/m^2=0.99$. We also use these methods to simulate a non-precessing binary black hole coalescence, where both black holes have $S/m^2=0.994$, nearly reaching the Novikov-Thorne upper bound for holes spun up by thin accretion disks. We demonstrate numerical convergence and estimate the numerical errors of the waveforms; we compare numerical waveforms from our simulations with post-Newtonian and effective-one-body waveforms; we compare the evolution of the black-hole masses and spins with analytic predictions; and we explore the effect of increasing spin magnitude on the orbital dynamics (the so-called "orbital hangup" effect).
Acoustic clouds: standing sound waves around a black hole analogue
Carolina L. Benone; Luis C. B. Crispino; Carlos Herdeiro; Eugen Radu
2015-01-28T23:59:59.000Z
Under certain conditions sound waves in fluids experience an acoustic horizon with analogue properties to those of a black hole event horizon. In particular, a draining bathtub-like model can give rise to a rotating acoustic horizon and hence a rotating black hole (acoustic) analogue. We show that sound waves, when enclosed in a cylindrical cavity, can form stationary waves around such rotating acoustic black holes. These acoustic perturbations display similar properties to the scalar clouds that have been studied around Kerr and Kerr-Newman black holes; thus they are dubbed acoustic clouds. We make the comparison between scalar clouds around Kerr black holes and acoustic clouds around the draining bathtub explicit by studying also the properties of scalar clouds around Kerr black holes enclosed in a cavity. Acoustic clouds suggest the possibility of testing, experimentally, the existence and properties of black hole clouds, using analog models.
Acoustic clouds: standing sound waves around a black hole analogue
Benone, Carolina L; Herdeiro, Carlos; Radu, Eugen
2014-01-01T23:59:59.000Z
Under certain conditions sound waves in fluids experience an acoustic horizon with analogue properties to those of a black hole event horizon. In particular, a draining bathtub-like model can give rise to a rotating acoustic horizon and hence a rotating black hole (acoustic) analogue. We show that sound waves, when enclosed in a cylindrical cavity, can form stationary waves around such rotating acoustic black holes. These acoustic perturbations display similar properties to the scalar clouds that have been studied around Kerr and Kerr-Newman black holes; thus they are dubbed acoustic clouds. We make the comparison between scalar clouds around Kerr black holes and acoustic clouds around the draining bathtub explicit by studying also the properties of scalar clouds around Kerr black holes enclosed in a cavity. Acoustic clouds suggest the possibility of testing, experimentally, the existence and properties of black hole clouds, using analog models.
Predictability in Quantum Gravity and Black Hole Evaporation
J. W. Moffat
1993-12-09T23:59:59.000Z
A possible resolution of the information loss paradox for black holes is proposed in which a phase transition occurs when the temperature of an evaporating black hole equals a critical value, $T_c$, and Lorentz invariance and diffeomorphism invariance are spontaneously broken. This allows a generalization of Schr\\"odinger's equation for the quantum mechanical density matrix, such that a pure state can evolve into a mixed state, because in the symmetry broken phase the conservation of energy-momentum is spontaneously violated. TCP invariance is also spontaneously broken together with time reversal invariance, allowing the existence of white holes, which are black holes moving backwards in time. Domain walls would form which separate the black holes and white holes (anti-black holes) in the broken symmetry regime, and the system could evolve into equilibrium producing a balance of information loss and gain.
Hole-transport material variation in fully vacuum deposited perovskite solar cells
Polander, Lauren E.; Pahner, Paul; Schwarze, Martin; Saalfrank, Matthias; Koerner, Christian; Leo, Karl, E-mail: karl.leo@iapp.de [Institut für Angewandte Photophysik, Technische Universität Dresden, 01069 Dresden (Germany)
2014-08-01T23:59:59.000Z
This work addresses the effect of energy level alignment between the hole-transporting material and the active layer in vacuum deposited, planar-heterojunction CH{sub 3}NH{sub 3}PbI{sub x?3}Cl{sub x} perovskite solar cells. Through a series of hole-transport materials, with conductivity values set using controlled p-doping of the layer, we correlate their ionization potentials with the open-circuit voltage of the device. With ionization potentials beyond 5.3 eV, a substantial decrease in both current density and voltage is observed, which highlights the delicate energetic balance between driving force for hole-extraction and maximizing the photovoltage. In contrast, when an optimal ionization potential match is found, the open-circuit voltage can be maximized, leading to power conversion efficiencies of up to 10.9%. These values are obtained with hole-transport materials that differ from the commonly used Spiro-MeO-TAD and correspond to a 40% performance increase versus this reference.
The Role of Primordial Kicks on Black Hole Merger Rates
Miroslav Micic; Tom Abel; Steinn Sigurdsson
2006-09-15T23:59:59.000Z
Primordial stars are likely to be very massive >30 Msun, form in isolation, and will likely leave black holes as remnants in the centers of their host dark matter halos. We expect primordial stars to form in halos in the mass range 10^6-10^10 Msun. Some of these early black holes, formed at redshifts z>10, could be the seed black hole for a significant fraction of the supermassive black holes found in galaxies in the local universe. If the black hole descendants of the primordial stars exist, their mergers with nearby supermassive black holes may be a prime candidate for long wavelength gravitational wave detectors. We simulate formation and evolution of dark matter halos in LambdaCDM universe. We seed high-redshift dark matter halos with early black holes, and explore the merger history of the host halos and the implications of black hole's kick velocities arising from their coalescence. The central concentration of low mass early black holes in present day galaxies is reduced if they experience even moderate kicks of tens of km/s. Even such modest kicks allow the black holes to leave their parent halo, which consequently leads to dynamical friction being less effective on the low mass black holes that were ejected, compared to those still embedded in their parent halos. Therefore, merger rates with central supermassive black holes in the largest halos may be reduced by more than an order of magnitude. Using analytical and illustrative cosmological N-body simulations, we quantify the role of kicks on the merger rates of black holes formed from massive metal free stars with supermassive black holes in present day galaxies.
Brunetto Marco Ziosi; Michela Mapelli; Marica Branchesi; Giuseppe Tormen
2014-05-20T23:59:59.000Z
In this paper, we study the formation and dynamical evolution of black hole-black hole (BH-BH) binaries in young star clusters (YSCs), by means of N-body simulations. The simulations include metallicity-dependent recipes for stellar evolution and stellar winds, and have been run for three different metallicities (Z = 0.01, 0.1 and 1 Zsun). Following recent theoretical models of wind mass-loss and core-collapse supernovae, we assume that the mass of the stellar remnants depends on the metallicity of the progenitor stars. We find that BH-BH binaries form efficiently because of dynamical exchanges: in our simulations, we find about 10 times more BH-BH binaries than double neutron star binaries. The simulated BH-BH binaries form earlier in metal-poor YSCs, which host more massive black holes (BHs) than in metal-rich YSCs. The simulated BH-BH binaries have very large chirp masses (up to 80 Msun), because the BH mass is assumed to depend on metallicity, and because BHs can grow in mass due to the merger with stars. The simulated BH-BH binaries span a wide range of orbital periods (10^-3-10^7 yr), and only a small fraction of them (0.3 per cent) is expected to merge within a Hubble time. We discuss the estimated merger rate from our simulations and the implications for Advanced VIRGO and LIGO.
Gravitational radiation from dynamical black holes
Sean A. Hayward
2005-12-26T23:59:59.000Z
An effective energy tensor for gravitational radiation is identified for uniformly expanding flows of the Hawking mass-energy. It appears in an energy conservation law expressing the change in mass due to the energy densities of matter and gravitational radiation, with respect to a Killing-like vector encoding a preferred flow of time outside a black hole. In a spin-coefficient formulation, the components of the effective energy tensor can be understood as the energy densities of ingoing and outgoing, transverse and longitudinal gravitational radiation. By anchoring the flow to the trapping horizon of a black hole in a given sequence of spatial hypersurfaces, there is a locally unique flow and a measure of gravitational radiation in the strong-field regime.
Laser stabilization using spectral hole burning
L. Rippe; B. Julsgaard; A. Walther; S. Kröll
2006-11-05T23:59:59.000Z
We have frequency stabilized a Coherent CR699-21 dye laser to a transient spectral hole on the 606 nm transition in Pr^{+3}:Y_2SiO_5. A frequency stability of 1 kHz has been obtained on the 10 microsecond timescale together with a long-term frequency drift below 1 kHz/s. RF magnetic fields are used to repopulate the hyperfine levels allowing us to control the dynamics of the spectral hole. A detailed theory of the atomic response to laser frequency errors has been developed which allows us to design and optimize the laser stabilization feedback loop, and specifically we give a stability criterion that must be fulfilled in order to obtain very low drift rates. The laser stability is sufficient for performing quantum gate experiments in Pr^{+3}:Y_2SiO_5.
Geometric description of BTZ black holes thermodynamics
Hernando Quevedo; Alberto Sanchez
2008-11-15T23:59:59.000Z
We study the properties of the space of thermodynamic equilibrium states of the Ba\\~nados-Teitelboim-Zanelli (BTZ) black hole in (2+1)-gravity. We use the formalism of geometrothermodynamics to introduce in the space of equilibrium states a $2-$dimensional thermodynamic metric whose curvature is non-vanishing, indicating the presence of thermodynamic interaction, and free of singularities, indicating the absence of phase transitions. Similar results are obtained for generalizations of the BTZ black hole which include a Chern-Simons term and a dilatonic field. Small logarithmic corrections of the entropy turn out to be represented by small corrections of the thermodynamic curvature, reinforcing the idea that thermodynamic curvature is a measure of thermodynamic interaction.
The hydraulic jump as a white hole
G. E. Volovik
2005-10-21T23:59:59.000Z
In the geometry of the circular hydraulic jump, the velocity of the liquid in the interior region exceeds the speed of capillary-gravity waves (ripplons), whose spectrum is `relativistic' in the shallow water limit. The velocity flow is radial and outward, and thus the relativistic ripplons cannot propagating into the interior region. In terms of the effective 2+1 dimensional Painleve-Gullstrand metric appropriate for the propagating ripplons, the interior region imitates the white hole. The hydraulic jump represents the physical singularity at the white-hole horizon. The instability of the vacuum in the ergoregion inside the circular hydraulic jump and its observation in recent experiments on superfluid 4He by E. Rolley, C. Guthmann, M.S. Pettersen and C. Chevallier in physics/0508200 are discussed.
Phase Structure of Higher Spin Black Holes
Abhishek Chowdhury; Arunabha Saha
2015-02-12T23:59:59.000Z
We revisit the study of the phase structure of higher spin black holes carried out in arXiv$:1210.0284$ using the "canonical formalism". In particular we study the low as well as high temperature regimes. We show that the Hawking-Page transition takes place in the low temperature regime. The thermodynamically favoured phase changes from conical surplus to black holes and then again to conical surplus as we increase temperature. We then show that in the high temperature regime the diagonal embedding gives the appropriate description. We also give a map between the parameters of the theory near the IR and UV fixed points. This makes the "good" solutions near one end map to the "bad" solutions near the other end and vice versa.
Quantized black holes, their spectrum and radiation
Khriplovich, I. B. [Budker Institute of Nuclear Physics (Russian Federation)], E-mail: khriplovich@inp.nsk.su
2008-04-15T23:59:59.000Z
Under quite natural general assumptions, the following results are obtained. The maximum entropy of a quantized surface is demonstrated to be proportional to the surface area in the classical limit. The general structure of the horizon spectrum is found. In the special case of loop quantum gravity, the value of the Barbero-Immirzi parameter is found. The discrete spectrum of thermal radiation of a black hole fits the Wien profile. The natural widths of the lines are much smaller than the distances between them. The total intensity of the thermal radiation is estimated. If the density of quantized primordial black holes is close to the present upper limit on the dark-matter density in our Solar system, the sensitivity of modern detectors is close to that necessary for detecting this radiation.
Charged Cylindrical Black Holes in Conformal Gravity
Jackson Levi Said; Joseph Sultana; Kristian Zarb Adami
2013-01-04T23:59:59.000Z
Considering cylindrical topology we present the static solution for a charged black hole in conformal gravity. We show that unlike the general relativistic case there are two different solutions, both including a factor that when set to zero recovers the familiar static charged black string solution in Einstein's theory. This factor gives rise to a linear term in the potential that also features in the neutral case and may have significant ramifications for particle trajectories.
Comparing quantum black holes and naked singularities
T. P. Singh
2000-12-21T23:59:59.000Z
There are models of gravitational collapse in classical general relativity which admit the formation of naked singularities as well as black holes. These include fluid models as well as models with scalar fields as matter. Even if fluid models were to be regarded as unphysical in their matter content, the remaining class of models (based on scalar fields) generically admit the formation of visible regions of finite but arbitrarily high curvature. Hence it is of interest to ask, from the point of view of astrophysics, as to what a stellar collapse leading to a naked singularity (or to a visible region of very high curvature) will look like, to a far away observer. The emission of energy during such a process may be divided into three phases - (i) the classical phase, during which matter and gravity can both be treated according to the laws of classical physics, (ii) the semiclassical phase, when gravity is treated classically but matter behaves as a quantum field, and (iii) the quantum gravitational phase. In this review, we first give a summary of the status of naked singularities in classical relativity, and then report some recent results comparing the semiclassical phase of black holes with the semiclassical phase of spherical collapse leading to a naked singularity. In particular, we ask how the quantum particle creation during the collapse leading to a naked singularity compares with the Hawking radiation from a star collapsing to form a black hole. It turns out that there is a fundamental difference between the two cases. A spherical naked star emits only about one Planck energy during its semiclassical phase, and the further evolution can only be determined by the laws of quantum gravity. This contrasts with the semiclassical evaporation of a black hole.
Noncommutative Inspired Black Holes in Extra Dimensions
Rizzo, Thomas G.
2006-06-07T23:59:59.000Z
In a recent string theory motivated paper, Nicolini, Smailagic and Spallucci (NSS) presented an interesting model for a noncommutative inspired, Schwarzschild-like black hole solution in 4-dimensions. The essential effect of having noncommutative co-ordinates in this approach is to smear out matter distributions on a scale associated with the turn-on of noncommutativity which was taken to be near the 4-d Planck mass. In particular, NSS assumed that this smearing was essentially Gaussian. This energy scale is sufficiently large that in 4-d such effects may remain invisible indefinitely. Extra dimensional models which attempt to address the gauge hierarchy problem, however, allow for the possibility that the effective fundamental scale may not be far from {approx} 1 TeV, an energy regime that will soon be probed by experiments at both the LHC and ILC. In this paper we generalize the NSS model to the case where flat, toroidally compactified extra dimensions are accessible at the TeV-scale and examine the resulting modifications in black hole properties due to the existence of noncommutativity. We show that while many of the noncommutativity-induced black hole features found in 4-d by NSS persist, in some cases there can be significant modifications due the presence of extra dimensions. We also demonstrate that the essential features of this approach are not particularly sensitive to the Gaussian nature of the smearing assumed by NSS.
Kerr black holes with scalar hair
Herdeiro, Carlos A R
2014-01-01T23:59:59.000Z
We present a family of solutions of Einstein's gravity minimally coupled to a complex, massive scalar field, describing asymptotically flat, spinning black holes with scalar hair and a regular horizon. These hairy black holes (HBHs) are supported by rotation and have no static limit. Besides mass M and angular momentum J, they carry a conserved, continuous Noether charge Q measuring the scalar hair. HBHs branch off from the Kerr metric at the threshold of the superradiant instability and reduce to spinning boson stars in the limit of vanishing horizon area. They overlap with Kerr black holes for a set of (M,J) values. A single Killing vector field preserves the solutions, tangent to the null geodesic generators of the event horizon. HBHs can exhibit sharp physical differences when compared to the Kerr solution, such as J/M^2>1, quadrupole moment larger than J^2/M and larger orbital angular velocity at the innermost stable circular orbit. Families of HBHs connected to the Kerr geometry should exist in scalar (...
RECOILING SUPERMASSIVE BLACK HOLES IN SPIN-FLIP RADIO GALAXIES
Liu, F. K.; Wang Dong [Department of Astronomy, Peking University, 100871 Beijing (China); Chen Xian, E-mail: fkliu@pku.edu.cn [Kavli Institute for Astronomy and Astrophysics, Peking University, 100871 Beijing (China)
2012-02-20T23:59:59.000Z
Numerical relativity simulations predict that coalescence of supermassive black hole (SMBH) binaries leads not only to a spin flip but also to a recoiling of the merger remnant SMBHs. In the literature, X-shaped radio sources are popularly suggested to be candidates for SMBH mergers with spin flip of jet-ejecting SMBHs. Here we investigate the spectral and spatial observational signatures of the recoiling SMBHs in radio sources undergoing black hole spin flip. Our results show that SMBHs in most spin-flip radio sources have mass ratio q {approx}> 0.3 with a minimum possible value q{sub min} {approx_equal} 0.05. For major mergers, the remnant SMBHs can get a kick velocity as high as 2100 km s{sup -1} in the direction within an angle {approx}< 40 Degree-Sign relative to the spin axes of remnant SMBHs, implying that recoiling quasars are biased to be with high Doppler-shifted broad emission lines while recoiling radio galaxies are biased to large apparent spatial off-center displacements. We also calculate the distribution functions of line-of-sight velocity and apparent spatial off-center displacements for spin-flip radio sources with different apparent jet reorientation angles. Our results show that the larger the apparent jet reorientation angle is, the larger the Doppler-shifting recoiling velocity and apparent spatial off-center displacement will be. We investigate the effects of recoiling velocity on the dust torus in spin-flip radio sources and suggest that recoiling of SMBHs would lead to 'dust-poor' active galactic nuclei. Finally, we collect a sample of 19 X-shaped radio objects and for each object give the probability of detecting the predicted signatures of recoiling SMBH.
Silk, Joseph [Institut d'Astrophysique, UMR 7095 CNRS, Universite Pierre et Marie Curie, 98bis Blvd Arago, F-75014 Paris (France); Department of Physics and Astronomy, The Johns Hopkins University, Homewood Campus, Baltimore, MD 21218 (United States); Beecroft Institute of Particle Astrophysics and Cosmology, Department of Physics, University of Oxford, Oxford OX1 3RH (United Kingdom)
2013-08-01T23:59:59.000Z
Pressure-regulated star formation is a simple variant on the usual supernova-regulated star formation efficiency that controls the global star formation rate as a function of cold gas content in star-forming galaxies, and accounts for the Schmidt-Kennicutt law in both nearby and distant galaxies. Inclusion of active galactic nucleus (AGN) induced pressure, by jets and/or winds that flow back onto a gas-rich disk, can lead, under some circumstances, to significantly enhanced star formation rates, especially at high redshift and most likely followed by the more widely accepted phase of star formation quenching. Simple expressions are derived that relate supermassive black hole growth, star formation, and outflow rates. The ratios of black hole to spheroid mass and of both black hole accretion and outflow rates to star formation rate are predicted as a function of time. I suggest various tests of the AGN-triggered star formation hypothesis.
Scattering of Sound Waves by a Canonical Acoustic Hole
Sam R. Dolan; Ednilton S. Oliveira; Luís C. B. Crispino
2009-04-06T23:59:59.000Z
This is a study of a monochromatic planar perturbation impinging upon a canonical acoustic hole. We show that acoustic hole scattering shares key features with black hole scattering. The interference of wavefronts passing in opposite senses around the hole creates regular oscillations in the scattered intensity. We examine this effect by applying a partial wave method to compute the differential scattering cross section for a range of incident wavelengths. We demonstrate the existence of a scattering peak in the backward direction, known as the glory. We show that the glory created by the canonical acoustic hole is approximately 170 times less intense than the glory created by the Schwarzschild black hole, for equivalent horizon-to-wavelength ratios. We hope that direct experimental observations of such effects may be possible in the near future.
Method and apparatus of assessing down-hole drilling conditions
Hall, David R. (Provo, UT); Pixton, David S. (Lehl, UT); Johnson, Monte L. (Orem, UT); Bartholomew, David B. (Springville, UT); Fox, Joe (Spanish Fork, UT)
2007-04-24T23:59:59.000Z
A method and apparatus for use in assessing down-hole drilling conditions are disclosed. The apparatus includes a drill string, a plurality of sensors, a computing device, and a down-hole network. The sensors are distributed along the length of the drill string and are capable of sensing localized down-hole conditions while drilling. The computing device is coupled to at least one sensor of the plurality of sensors. The data is transmitted from the sensors to the computing device over the down-hole network. The computing device analyzes data output by the sensors and representative of the sensed localized conditions to assess the down-hole drilling conditions. The method includes sensing localized drilling conditions at a plurality of points distributed along the length of a drill string during drilling operations; transmitting data representative of the sensed localized conditions to a predetermined location; and analyzing the transmitted data to assess the down-hole drilling conditions.
Connecting horizon pixels and interior voxels of a black hole
Piero Nicolini; Douglas Singleton
2014-10-03T23:59:59.000Z
In this paper we discuss to what extent one can infer details of the interior structure of a black hole based on its horizon. Recalling that black hole thermal properties are connected to the non-classical nature of gravity, we circumvent the restrictions of the no hair theorem by postulating that the black hole interior is singularity free due to violations of the usual energy conditions. Further these conditions allow one to establish a one-to-one, holographic projection between Planckian areal "bits" on the horizon and "voxels", representing the gravitational degrees of freedom in the black hole interior. We illustrate the repercussions of this idea by discussing an example of the black hole interior consisting of a de Sitter core postulated to arise from the local graviton quantum vacuum energy. It is shown that the black hole entropy can emerge as the statistical entropy of a gas of voxels.
Black holes in extra dimensions can decay on the bulk
A. K. Chaudhuri
2003-01-08T23:59:59.000Z
In the extra dimensional theories, with TeV scale Plank constant, black holes may be produced in the Large Hadron Collider experiments. We have argued that in the d-dimensional black hole, the intrinsically 4-dimensional brane fields do not see the same geometry at the horizon, as in a 4-dimensional space-time. Kaluza-Klein modes invades the brane and surroundings and the brane fields can be considered as a thermal system at the temperature of the black hole. From energy and entropy consideration, we show that whether or not a six-dimensional black hole will decay by emitting Kaluza-Klein modes or the standard model particles, will depend on the length scale of the extra dimensions as well as on the mass of the black hole. For higher dimensional black holes, Kaluza-Klein modes will dominate the decay.
Articles which include chevron film cooling holes, and related processes
Bunker, Ronald Scott; Lacy, Benjamin Paul
2014-12-09T23:59:59.000Z
An article is described, including an inner surface which can be exposed to a first fluid; an inlet; and an outer surface spaced from the inner surface, which can be exposed to a hotter second fluid. The article further includes at least one row or other pattern of passage holes. Each passage hole includes an inlet bore extending through the substrate from the inlet at the inner surface to a passage hole-exit proximate to the outer surface, with the inlet bore terminating in a chevron outlet adjacent the hole-exit. The chevron outlet includes a pair of wing troughs having a common surface region between them. The common surface region includes a valley which is adjacent the hole-exit; and a plateau adjacent the valley. The article can be an airfoil. Related methods for preparing the passage holes are also described.
LOWFREQUENCY RADIO OBSERVATIONS OF XRAY GHOST BUBBLES A2597: A HISTORY RADIO ACTIVITY THE CORE
Sarazin, Craig
LOWÂFREQUENCY RADIO OBSERVATIONS OF XÂRAY GHOST BUBBLES A2597: A HISTORY RADIO ACTIVITY THE CORE T showed ``ghost holes'' XÂray emission west northeast central radio galaxy PKS 2322#123. Previous radio observations detect radio emission coming from interior XÂray holes. present lowÂfrequency observations A2597
KKW Analysis for the Dyadosphere of a Charged Black Hole
I. Radinschi
2005-11-28T23:59:59.000Z
The Keski-Vakkuri, Kraus and Wilczek (KKW) analysis is used to compute the temperature and entropy in the dyadosphere of a charged black hole solution. For our purpose we choose the dyadosphere region of the Reissner-Nordstrom black hole solution. Our results show that the expressions of the temperature and entropy in the dyadosphere of this charged black hole are not the Hawking temperature and the Bekenstein-Hawking entropy, respectively.
A Quantum Material Model of Static Schwarzschild Black Holes
S. -T. Sung
1997-03-16T23:59:59.000Z
A quantum-mechanical prescription of static Einstein field equation is proposed in order to construct the matter-metric eigen-states in the interior of a static Schwarzschild black hole where the signature of space-time is chosen as (--++). The spectrum of the quantum states is identified to be the integral multiples of the surface gravity. A statistical explanation of black hole entropy is given and a quantisation rule for the masses of Schwarzschild black holes is proposed.
A mathematical simulation of horizontal drain-hole performance
Cheng, Thomas Ru-Kang
1984-01-01T23:59:59.000Z
Flow Rate Obtained From This Model and From BOSS-AIM. 22 Comparison of The Gas-Oil Ratio Obtained From This Model and From BOSS-AIM. 24 Relative Positions of Conventional Well and Horizontal Drain-Hole in Simulation Runs. . . . . 27 Comparison... of The Economic Oil Recovery Obtained From Horizontal Drain-Hole and From Conventional Well. . . . . . . 28 Comparison of The Cumulative Gas-Oil Ratio Obtained From Horizontal Drain-Hole and From Conventional Well. . . 29 Effect of Horizontal Drain...
Classical and Quantum Properties of Liouville Black Holes
R. B. Mann
1994-04-25T23:59:59.000Z
Black hole spacetimes can arise when a Liouville field is coupled to two- dimensional gravity. Exact solutions are obtained both classically and when quantum corrections due to back reaction effects are included. The black hole temperature depends upon the mass and the thermodynamic limit breaks down before evaporation of the black hole is complete, indicating that higher-loop effects must be included for a full description of the process.
Brownian Motion of Black Holes in Dense Nuclei
David Merritt; Peter Berczik; Frederik Laun
2006-10-18T23:59:59.000Z
We evaluate the Brownian motion of a massive particle ("black hole") at the center of a galaxy using N-body simulations. Our galaxy models have power-law central density cusps like those observed at the centers of elliptical galaxies. The simulations show that the black hole achieves a steady-state kinetic energy that is substantially different than would be predicted based on the properties of the galaxy model in the absence of the black hole. The reason appears to be that the black hole responds to stars whose velocities have themselves been raised by the presence of the black hole. Over a wide range of density slopes and black hole masses, the black hole's mean kinetic energy is equal to what would be predicted under the assumption that it is in energy equipartition with stars lying within a distance ~r_h/2 from it, where r_h is the black hole's influence radius. The dependence of the Brownian velocity on black hole mass is approximately ~ 1/M^{1/(3-gamma)} with gamma the power-law index of the stellar density profile, rho~1/r^gamma. This is less steep than the 1/M dependence predicted in a model where the effect of the black hole on the stellar velocities is ignored. The influence of a stellar mass spectrum on the black hole's Brownian motion is also evaluated and found to be consistent with predictions from Chandrasekhar's theory. We use these results to derive a probability function for the mass of the Milky Way black hole based on a measurement of its proper motion velocity. Interesting constraints on M will require a velocity resolution exceeding 0.5 km/s.
Small Hairy Black Holes in Global AdS Spacetime
Pallab Basu; Jyotirmoy Bhattacharya; Sayantani Bhattacharyya; R. Loganayagam; Shiraz Minwalla; V. Umesh
2010-05-16T23:59:59.000Z
We study small charged black holes in global AdS spacetime in the presence of a charged massless minimally coupled scalar field. In a certain parameter range these black holes suffer from well known superradiant instabilities. We demonstrate that the end point of the resultant tachyon condensation process is a hairy black hole which we construct analytically in a perturbative expansion in the black hole radius. At leading order our solution is a small undeformed RNAdS black hole immersed into a charged scalar condensate that fills the AdS `box'. These hairy black hole solutions appear in a two parameter family labelled by their mass and charge. Their mass is bounded from below by a function of their charge; at the lower bound a hairy black hole reduces to a regular horizon free soliton which can also be thought of as a nonlinear Bose condensate. We compute the microcanonical phase diagram of our system at small mass, and demonstrate that it exhibits a second order `phase transition' between the RNAdS black hole and the hairy black hole phases.
Hydrodynamic model for electron-hole plasma in graphene
D. Svintsov; V. Vyurkov; S. Yurchenko; T. Otsuji; V. Ryzhii
2012-01-03T23:59:59.000Z
We propose a hydrodynamic model describing steady-state and dynamic electron and hole transport properties of graphene structures which accounts for the features of the electron and hole spectra. It is intended for electron-hole plasma in graphene characterized by high rate of intercarrier scattering compared to external scattering (on phonons and impurities), i.e., for intrinsic or optically pumped (bipolar plasma), and gated graphene (virtually monopolar plasma). We demonstrate that the effect of strong interaction of electrons and holes on their transport can be treated as a viscous friction between the electron and hole components. We apply the developed model for the calculations of the graphene dc conductivity, in particular, the effect of mutual drag of electrons and holes is described. The spectra and damping of collective excitations in graphene in the bipolar and monopolar limits are found. It is shown that at high gate voltages and, hence, at high electron and low hole densities (or vice-versa), the excitations are associated with the self-consistent electric field and the hydrodynamic pressure (plasma waves). In intrinsic and optically pumped graphene, the waves constitute quasineutral perturbations of the electron and hole densities (electron-hole sound waves) with the velocity being dependent only on the fundamental graphene constants.
Energy Distribution of a Charged Regular Black Hole
Irina Radinschi
2000-11-20T23:59:59.000Z
We calculate the energy distribution of a charged regular black hole by using the energy-momentum complexes of Einstein and M{\\o}ller.
Core Holes At Valles Caldera - Sulphur Springs Geothermal Area...
of core holes were drilled from 1984 to 1988 as a part of the Continental Scientific Drilling Program (CSDP) to better understand the stratigraphy, structure, hydrothermal...
Core Holes At Valles Caldera - Redondo Geothermal Area (Goff...
of core holes were drilled from 1984 to 1988 as a part of the Continental Scientific Drilling Program (CSDP) to better understand the stratigraphy, structure, hydrothermal...
Spectroscopy of the Einstein-Maxwell-Dilaton-Axion black hole
Deyou Chen; Haitang Yang
2012-10-03T23:59:59.000Z
The entropy spectrum of a spherically symmetric black hole was derived via the Bohr-Sommerfeld quantization rule in Majhi and Vagenas's work. Extending this work to charged and rotating black holes, we quantize the horizon area and the entropy of an Einstein-Maxwell-Dilaton-Axion (EMDA) black hole via the Bohr-Sommerfeld quantization rule and the adiabatic invariance. The result shows the area spectrum and the entropy spectrum are respectively equally spaced and independent on the parameters of the black hole.
Particle Acceleration Around 5-dimensional Kerr Black Hole
Ahmadjon Abdujabbarov; Naresh Dadhich; Bobomurat Ahmedov; Husan Eshkuvatov
2013-12-11T23:59:59.000Z
On the lines of the 4-dimensional Kerr black hole we consider the particle acceleration near a 5-dimensional Kerr black hole which has the two rotation parameters. It turns out that the center of mass energy of the two equal mass colliding particles as expected diverges for the extremal black hole and there is a symmetry in the results for $\\theta = 0, \\pi/2$. Because of the two rotation parameters, $r=0$ can be a horizon without being a curvature singularity. It is shown that the acceleration of particles to high energies near the 5-D extreme rotating black hole avoids fine-tuning of the angular momentum of particles.
Moduli vacuum bubbles produced by evaporating black holes
Morris, J. R. [Physics Department, Indiana University Northwest, 3400 Broadway, Gary, Indiana 46408 (United States)
2007-10-15T23:59:59.000Z
We consider a model with a toroidally compactified extra dimension giving rise to a temperature-dependent 4D effective potential with one-loop contributions due to the Casimir effect, along with a 5D cosmological constant. The forms of the effective potential at low and high temperatures indicate a possibility for the formation of a domain wall bubble, formed by the modulus scalar field, surrounding an evaporating black hole. This is viewed as an example of a recently proposed black hole vacuum bubble arising from matter-sourced moduli fields in the vicinity of an evaporating black hole [D. Green, E. Silverstein, and D. Starr, Phys. Rev. D 74, 024004 (2006)]. The black hole bubble can be highly opaque to lower-energy particles and photons, and thereby entrap them within. For high-temperature black holes, there may also be a symmetry-breaking black hole bubble of false vacuum of the type previously conjectured by Moss [I. G. Moss, Phys. Rev. D 32, 1333 (1985)], tending to reflect low-energy particles from its wall. A double bubble composed of these two different types of bubble may form around the black hole, altering the hole's emission spectrum that reaches outside observers. Smaller mass black holes that have already evaporated away could have left vacuum bubbles behind that contribute to the dark matter.
Thermal Gradient Holes At Breitenbush Hot Springs Area (Ingebritsen...
(1993) Heat Flow From Four New Research Drill Holes In The Western Cascades, Oregon, Usa Additional References Retrieved from "http:en.openei.orgwindex.php?titleThermalGr...
accreting black holes: Topics by E-print Network
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
collapse or accretion event. We consider how a red hole solution can solve the "energy crisis" and power extremely energetic gamma ray bursts and hypernovae. James S. Graber...
Complete single-horizon quantum corrected black hole spacetime
Peltola, Ari; Kunstatter, Gabor [Department of Physics and Winnipeg Institute for Theoretical Physics, University of Winnipeg, 515 Portage Avenue, Winnipeg, Manitoba, R3B 2E9 (Canada)
2009-03-15T23:59:59.000Z
We show that a semiclassical polymerization of the interior of Schwarzschild black holes gives rise to a tantalizing candidate for a nonsingular, single-horizon black hole spacetime. The exterior has nonzero quantum stress energy but closely approximates the classical spacetime for macroscopic black holes. The interior exhibits a bounce at a microscopic scale and then expands indefinitely to a Kantowski-Sachs spacetime. Polymerization therefore removes the singularity and produces a scenario reminiscent of past proposals for universe creation via quantum effects inside a black hole.
Exploring higher dimensional black holes at the large hadron collider.
Harris, Chris M; Palmer, M J; Parker, Michael A; Richardson, P
cross section for production of black holes not too much heavier than the fundamental Planck scale corresponds to a production rate of a few Hertz at the LHC design luminosity. In the following sections, the process of the black hole production and decay... scattering in quantum gravity, hep-th/9906038. [7] R. Emparan, G. T. Horowitz, and R. C. Myers, Exact description of black holes on branes, JHEP 01 (2000) 007, [hep-th/9911043]. [8] S. B. Giddings and S. Thomas, High energy colliders as black hole factories...
Entropy: From Black Holes to Ordinary Systems
J. P. Badiali
2005-05-11T23:59:59.000Z
Several results of black holes thermodynamics can be considered as firmly founded and formulated in a very general manner. From this starting point we analyse in which way these results may give us the opportunity to gain a better understanding in the thermodynamics of ordinary systems for which a pre-relativistic description is sufficient. First, we investigated the possibility to introduce an alternative definition of the entropy basically related to a local definition of the order in a spacetime model rather than a counting of microstates. We show that such an alternative approach exists and leads to the traditional results provided an equilibrium condition is assumed. This condition introduces a relation between a time interval and the reverse of the temperature. We show that such a relation extensively used in the black hole theory, mainly as a mathematical trick, has a very general and physical meaning here; in particular its derivation is not related to the existence of a canonical density matrix. Our dynamical approach of thermodynamic equilibrium allows us to establish a relation between action and entropy and we show that an identical relation exists in the case of black holes. The derivation of such a relation seems impossible in the Gibbs ensemble approach of statistical thermodynamics. From these results we suggest that the definition of entropy in terms of order in spacetime should be more general that the Boltzmann one based on a counting of microstates. Finally we point out that these results are obtained by reversing the traditional route going from the Schr\\"{o}dinger equation to statistical thermodynamics.
Density matrix of black hole radiation
Lasma Alberte; Ram Brustein; Andrei Khmelnitsky; A. J. M. Medved
2015-02-09T23:59:59.000Z
Hawking's model of black hole evaporation is not unitary and leads to a mixed density matrix for the emitted radiation, while the Page model describes a unitary evaporation process in which the density matrix evolves from an almost thermal state to a pure state. We compare a recently proposed model of semiclassical black hole evaporation to the two established models. In particular, we study the density matrix of the outgoing radiation and determine how the magnitude of the off-diagonal corrections differs for the three frameworks. For Hawking's model, we find power-law corrections to the two-point functions that induce exponentially suppressed corrections to the off-diagonal elements of the full density matrix. This verifies that the Hawking result is correct to all orders in perturbation theory and also allows one to express the full density matrix in terms of the single-particle density matrix. We then consider the semiclassical theory for which the corrections, being non-perturbative from an effective field-theory perspective, are much less suppressed and grow monotonically in time. In this case, the R\\'enyi entropy for the outgoing radiation is shown to grow linearly at early times; but this growth slows down and the entropy eventually starts to decrease at the Page time. In addition to comparing models, we emphasize the distinction between the state of the radiation emitted from a black hole, which is highly quantum, and that of the radiation emitted from a typical classical black body at the same temperature.
ACCRETION-JET CONNECTION IN BLACK HOLES THE ORIGIN OF STELLAR BLACK HOLES &
Maryland at College Park, University of
of a sudden drop of the hard X-rays..." ·"The particles (corona/inner disk) are blown away..." ·"Jets have Direct collapse depends on: ·Metal content ·Mass of the core ·Angular momentum Can this model be tested observationally ? #12;HOW ARE FORM BLACK HOLE BINARIES ? CORE COLLAPSE MODELS: (Fryer & Kalogera ; Woosley & Heger
Tunneling into black hole, escape from black hole, reflection from horizon and pair creation
V. V. Flambaum
2004-08-05T23:59:59.000Z
Within classical general relativity, a particle cannot reach the horizon of a black hole during a finite time, in the reference frame of an external observer; a particle inside cannot escape from a black hole; and the horizon does not produce any reflection. We argue that these processes may possibly be allowed in the quantum world. It is known that quantum mechanics allows pair creation at the horizon (one particle inside, another particle outside) and Hawking radiation. One can extend this idea to propose other processes. Tunneling of an external particle inside black hole may be produced by the creation of a pair at the horizon, followed by the annihilation of one created particle with the initial particle outside, with the other created particle appearing inside. Escape of a particle from a black hole may result from the creation of a pair, followed by the annihilation of one created particle with the particle inside, with the other created particle appearing outside. The escape may allow the transfer of information to the outside.Finally, the reflection of an external particle from the horizon may be modelled by a combination of the two processes presented above. The relationship between these "pair creation-annihilation'' mechanisms and the "horizon tunneling" calculations [1-5] is discussed.
Collective Excitations in Electron-Hole Bilayers
Kalman, G. J. [Department of Physics, Boston College, Chestnut Hill, Massachusetts 02467 (United States); Hartmann, P.; Donko, Z. [Research Institute for Solid State Physics and Optics, Hungarian Academy of Sciences, P.O. Box 49, H-1525 Budapest (Hungary); Golden, K. I. [Department of Mathematics and Statistics and Department of Physics, University of Vermont, Burlington, Vermont 05401 (United States)
2007-06-08T23:59:59.000Z
We report a combined analytic and molecular dynamics analysis of the collective mode spectrum of a bipolar (electron-hole) bilayer in the strong coupling classical limit. A robust, isotropic energy gap is identified in the out-of-phase spectra, generated by the combined effect of correlations and of the excitation of the bound dipoles. In the in-phase spectra we identify longitudinal and transverse acoustic modes wholly maintained by correlations. Strong nonlinear generation of higher harmonics of the fundamental dipole oscillation frequency and the transfer of harmonics between different modes is observed.
The effects of fastener hole defects
Andrews, Scot D.
1991-01-01T23:59:59.000Z
) August 1991 ABSTRACT The Effects of Fastener Hole Defects. (August 1991) Scot D. Andrews, B. S. , Texas A8rM University Chair of Advisory Committee: Dr. Orden O. Ochoa The influence of drilling-induced defects, such as delamination, on the fatigue... ambient and elevated temperature wet conditions. Specimens were tested in a bearing tension frame to static failure in order to measure the failure load and to calculate pin bearing stress. From static test results, a fatigue load was selected as 66...
Formation of subhorizon black holes from preheating
E. Torres-Lomas; Juan Carlos Hidalgo; Karim A. Malik; L. Arturo Ureña-López
2014-04-29T23:59:59.000Z
We study the production of primordial black holes (PBHs) during the preheating stage that follows a chaotic inflationary phase. The scalar fields present in the process are evolved numerically using a modified version of the HLATTICE code. From the output of the numerical simulation, we compute the probability distribution of curvature fluctuations, paying particular attention to sub-horizon scales. We find that in some specific models these modes grow to large amplitudes developing highly non-Gaussian probability distributions. We then calculate PBH abundances using the standard Press-Schechter criterion and find that overproduction of PBHs is likely in some regions of the chaotic preheating parameter space.
False Vacuum Black Holes and Universes
R. G. Daghigh; J. I. Kapusta; Y. Hosotani
2000-08-01T23:59:59.000Z
We construct a black hole whose interior is the false vacuum and whose exterior is the true vacuum of a classical field theory. From the outside the metric is the usual Schwarzschild one, but from the inside the space is de Sitter with a cosmological constant determined by the energy of the false vacuum. The parameters of the field potential may allow for the false vacuum to exist for more than the present age of the universe. A potentially relevant effective field theory within the context of QCD results in a Schwarzschild radius of about 200 km.
Down-hole periodic seismic generator
Hardee, H.C.; Hills, R.G.; Striker, R.P.
1982-10-28T23:59:59.000Z
A down hole periodic seismic generator system is disclosed for transmitting variable frequency, predominantly shear-wave vibration into earth strata surrounding a borehole. The system comprises a unitary housing operably connected to a well head by support and electrical cabling and contains clamping apparatus for selectively clamping the housing to the walls of the borehole. The system further comprises a variable speed pneumatic oscillator and a self-contained pneumatic reservoir for producing a frequency-swept seismic output over a discrete frequency range.
Black hole birth captured by cosmic voyeurs
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
AFDC Printable Version Share this resource Send a link to EERE: Alternative Fuels Data Center Home Page to someone by E-mail Share EERE: Alternative Fuels Data Center Home Page on Facebook Tweet about EERE: Alternative Fuels Data Center Home Page on Twitter Bookmark EERE: Alternative1 First Use of Energy for All Purposes (Fuel and Nonfuel), 2002; Level: National5Sales for4,645 3,625govInstrumentstdmadapInactiveVisiting the TWPSuccess Stories Site MapSolar energy newsVideoProductionBlack hole
Thin n-in-p planar pixel sensors and active edge sensors for the ATLAS upgrade at HL-LHC
S. Terzo; A. Macchiolo; R. Nisius; B. Paschen
2014-11-20T23:59:59.000Z
Silicon pixel modules employing n-in-p planar sensors with an active thickness of 200 $\\mu$m, produced at CiS, and 100-200 $\\mu$m thin active/slim edge sensor devices, produced at VTT in Finland have been interconnected to ATLAS FE-I3 and FE-I4 read-out chips. The thin sensors are designed for high energy physics collider experiments to ensure radiation hardness at high fluences. Moreover, the active edge technology of the VTT production maximizes the sensitive region of the assembly, allowing for a reduced overlap of the modules in the pixel layer close to the beam pipe. The CiS production includes also four chip sensors according to the module geometry planned for the outer layers of the upgraded ATLAS pixel detector to be operated at the HL-LHC. The modules have been characterized using radioactive sources in the laboratory and with high precision measurements at beam tests to investigate the hit efficiency and charge collection properties at different bias voltages and particle incidence angles. The performance of the different sensor thicknesses and edge designs are compared before and after irradiation up to a fluence of $1.4\\times10^{16}n_{eq}/cm^{2}$.
Wontae Kim; Edwin J. Son; Myungseok Yoon
2008-01-09T23:59:59.000Z
We study thermodynamic quantities of an acoustic black hole and its thermodynamic stability in a cavity based on the generalized uncertainty principle. It can be shown that there is a minimal black hole which can be a stable remnant after black hole evaporation. Moreover, the behavior of the free energy shows that the large black hole is stable too. Therefore, the acoustic black hole can decay into the remnant or the large black hole.
Archaeological studies at Drill Hole U20az Pahute Mesa, Nye county, Nevada. [Contains bibliography
Simmons, A.H.; Hemphill, M.L.; Henton, G.H.; Lockett, C.L.; Nials, F.L.; Pippin, L.C.; Walsh, L.
1991-07-01T23:59:59.000Z
During the summer of 1987, the Quaternary Sciences Center (formerly Social Science Center) of the Desert Research Institute (DRI), University of Nevada System, conducted data recovery investigations at five archaeological sites located near Drill Hole U20az on the Nevada Test Site in southern Nevada. These sites were among 12 recorded earlier during an archaeological survey of the drill hole conducted as part of the environmental compliance activities of the Department of Energy (DOE). The five sites discussed in this report were considered eligible for the National Register of Historic Places and were in danger of being adversely impacted by construction activities or by effects of the proposed underground nuclear test. Avoidance of these sites was not a feasible alternative; thus DRI undertook a data recovery program to mitigate expected adverse impacts. DRI's research plan included controlled surface collections and excavation of the five sites in question, and had the concurrence of the Nevada Division of Historic Preservation and Archaeology and the Advisory Council of Historic Preservation. Of the five sites investigated, the largest and most complex, 26Ny5207, consists of at least three discrete artifact concentrations. Sites 26Ny5211 and 26Ny5215, both yielded considerable assemblages. Site 26Ny5206 is very small and probably is linked to 26Ny5207. Site 26Ny5205 contained a limited artifact assemblage. All of the sites were open-air occurrences, and, with one exception contained no or limited subsurface cultural deposits. Only two radiocarbon dates were obtained, both from 26Ny5207 and both relatively recent. While the investigations reported in the volume mitigate most of the adverse impacts from DOE activities at Drill Hole U20az, significant archaeological sites may still exist in the general vicinity. Should the DOE conduct further activities in the region, additional cultural resource investigations may be required. 132 refs., 71 figs., 44 tabs.
Slim Lake, Minnesota: Energy Resources | Open Energy Information
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High Precision Geophysics & Detailed Structural Exploration & Slim Well
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On the Energy of Stringy Black Holes
Irina Radinschi; I-Ching Yang
2004-06-14T23:59:59.000Z
It is well-known that one of the most interesting and challenging problems of General Relativity is the energy and momentum localization. There are many attempts to evaluate the energy distribution in a general relativistic system. One of the methods used for the energy and momentum localization is the one which used the energy-momentum complexes. After the Einstein work, a large number of definitions for the energy distribution was given. We mention the expressions proposed by Landau and Lifshitz, Papapetrou, Bergmann, Weinberg and M{\\o}ller. The Einstein, Landau and Lifshitz, Papapetrou, Bergmann and Weinberg energy-momentum complexes are restricted to calculate the energy distribution in quasi-Cartesian coordinates. The energy-momentum complex of M{\\o}ller gives the possibility to make the calculations in any coordinate system. In this paper we calculate the energy distribution of three stringy black hole solutions in the M{\\o}ller prescription. The M{\\o}ller energy-momentum complex gives us a consistent result for these three situations. Keywords: M{\\o}ller energy-momentum complex, charged black hole solution in heterotic string theory PACS: 04. 20 Dw, 04. 70. Bw,
Spin interference of holes in silicon nanosandwiches
Bagraev, N. T., E-mail: Bagraev@mail.ioffe.ru; Danilovskii, E. Yu.; Klyachkin, L. E.; Malyarenko, A. M. [Russian Academy of Sciences, Ioffe Physical Technical Institute (Russian Federation); Mashkov, V. A. [St. Petersburg State Polytechnical University (Russian Federation)
2012-01-15T23:59:59.000Z
Spin-dependent transport of holes is studied in silicon nanosandwiches on an n-Si (100) surface which are represented by ultranarrow p-Si quantum wells confined by {delta}-barriers heavily doped with boron. The measurement data of the longitudinal and Hall voltages as functions of the top gate voltage without an external magnetic field show the presence of edge conduction channels in the silicon nanosandwiches. An increase in the stabilized source-drain current within the range 0.25-5 nA subsequently exhibits the longitudinal conductance value 4e{sup 2}/h, caused by the contribution of the multiple Andreev reflection, the value 0.7(2e{sup 2}/h) corresponding to the known quantum conductance staircase feature, and displays Aharonov-Casher oscillations, which are indicative of the spin polarization of holes in the edge channels. In addition, at a low stabilized source-drain current, due to spin polarization, a nonzero Hall voltage is detected which is dependent on the top gate voltage; i. e., the quantum spin Hall effect is observed. The measured longitudinal I-V characteristics demonstrate Fiske steps and a negative differential resistance caused by the generation of electromagnetic radiation as a result of the Josephson effect. The results obtained are explained within a model of topological edge states which are a system of superconducting channels containing quantum point contacts transformable to single Josephson junctions at an increasing stabilized source-drain current.
Cruz-Dombriz, A. de la; Dobado, A.; Maroto, A. L. [Departamento de Fisica Teorica I, Universidad Complutense de Madrid, 28040 Madrid (Spain)
2009-12-15T23:59:59.000Z
In the context of f(R) theories of gravity, we address the problem of finding static and spherically symmetric black hole solutions. Several aspects of constant curvature solutions with and without electric charge are discussed. We also study the general case (without imposing constant curvature). Following a perturbative approach around the Einstein-Hilbert action, it is found that only solutions of the Schwarzschild-(anti) de Sitter type are present up to second order in perturbations. Explicit expressions for the effective cosmological constant are obtained in terms of the f(R) function. Finally, we have considered the thermodynamics of black holes in anti-de Sitter space-time and found that this kind of solution can only exist provided the theory satisfies R{sub 0}+f(R{sub 0})<0. Interestingly, this expression is related to the condition which guarantees the positivity of the effective Newton's constant in this type of theories. In addition, it also ensures that the thermodynamical properties in f(R) gravities are qualitatively similar to those of standard general relativity.
Asymptotically Lifshitz brane-world black holes
Ranjbar, Arash, E-mail: a_ranjbar@sbu.ac.ir; Sepangi, Hamid Reza, E-mail: hr-sepangi@sbu.ac.ir; Shahidi, Shahab, E-mail: s_shahidi@sbu.ac.ir
2012-12-15T23:59:59.000Z
We study the gravity dual of a Lifshitz field theory in the context of a RSII brane-world scenario, taking into account the effects of the extra dimension through the contribution of the electric part of the Weyl tensor. We study the thermodynamical behavior of such asymptotically Lifshitz black holes. It is shown that the entropy imposes the critical exponent z to be bounded from above. This maximum value of z corresponds to a positive infinite entropy as long as the temperature is kept positive. The stability and phase transition for different spatial topologies are also discussed. - Highlights: Black-Right-Pointing-Pointer Studying the gravity dual of a Lifshitz field theory in the context of brane-world scenario. Black-Right-Pointing-Pointer Studying the thermodynamical behavior of asymptotically Lifshitz black holes. Black-Right-Pointing-Pointer Showing that the entropy imposes the critical exponent z to be bounded from above. Black-Right-Pointing-Pointer Discussing the phase transition for different spatial topologies.
Black holes can have curly hair
K. A. Bronnikov; O. B. Zaslavskii
2008-05-29T23:59:59.000Z
We study equilibrium conditions between a static, spherically symmetric black hole and classical matter in terms of the radial pressure to density ratio p_r/\\rho = w(u), where u is the radial coordinate. It is shown that such an equilibrium is possible in two cases: (i) the well-known case w\\to -1 as $u\\to u_h (the horizon), i.e., "vacuum" matter, for which \\rho(u_h) can be nonzero; (ii) w \\to -1/(1+2k) and \\rho \\sim (u-u_h)^k as u\\to u_h, where k>0 is a positive integer (w=-1/3 in the generic case k=1). A non-interacting mixture of these two kinds of matter can also exist. The whole reasoning is local, hence the results do not depend on any global or asymptotic conditions. They mean, in particular, that a static black hole cannot live inside a star with nonnegative pressure and density. As an example, an exact solution for an isotropic fluid with w = -1/3 (that is, a fluid of disordered cosmic strings), with or without vacuum matter, is presented.
Filing Holes in Complex Surfaces Using Volumetric Diffusion
Kazhdan, Michael
Method for Building Complex Models From range Images, '96) Applies line of sight constraints based components Complex hole geometry Construction of an arbitrary mesh can result in non-manifold surfaceFiling Holes in Complex Surfaces Using Volumetric Diffusion J. Davis, S. Marschner, M. Garr and M
Synchronization Helps Robots to Detect Black Holes in Directed Graphs
Pinotti, Maria Cristina
nodes are the so called black hole nodes, and once a robot enters in one of them, it is destroyed supported by the Italian CNR Short-Term Mobility Program. #12;1 Introduction The subject of exploring that destroy any entering entity. Such nodes are called black holes, and the exploration of a graph
Nonrotating black hole in a post-Newtonian tidal environment
Stephanne Taylor; Eric Poisson
2008-09-11T23:59:59.000Z
We examine the motion and tidal dynamics of a nonrotating black hole placed within a post-Newtonian external spacetime. The tidal perturbation created by the external environment is treated as a small perturbation. At a large distance from the black hole, the gravitational field of the external distribution of matter is assumed to be sufficiently weak to be adequately described by the (first) post-Newtonian approximation to general relativity. There, the black hole is treated as a monopole contribution to the total gravitational field. There exists an overlap in the domains of validity of each description, and the black-hole and post-Newtonian metrics are matched in the overlap. The matching procedure produces the equations of motion for the black hole and the gravito-electric and gravito-magnetic tidal fields acting on the black hole. We first calculate the equations of motion and tidal fields by making no assumptions regarding the nature of the post-Newtonian environment; this could contain a continuous distribution of matter or any number of condensed bodies. We next specialize our discussion to a situation in which the black hole is a member of a post-Newtonian two-body system. As an application of our results, we examine the geometry of the deformed event horizon and calculate the tidal heating of the black hole, the rate at which it acquires mass as a result of its tidal interaction with the companion body.
Extracting Energy from Black Hole through Transition Region
Li-Xin Li
2000-07-24T23:59:59.000Z
A new scenario for extracting energy from a Kerr black hole is proposed. With magnetic field lines connecting plasma particles inside the ergosphere with remote loads, the frame dragging twists the field lines so that energy and angular momentum are extracted from the plasma particles. If the magnetic field is strong enough, the energy extracted from the particles can be so large that the particles have negative energy as they fall into the black hole. So effectively the energy is extracted from the black hole. The particles inside the ergosphere can be continuously replenished with accretion from a disk surrounding the black hole, so a transition region with sufficient amount of plasma is formed between the black hole's horizon and the inner edge of the disk. Thus the energy can be continuously extracted from the black hole through the transition region. This may be the most efficient way for extracting energy from a Kerr black hole: in principle almost all of the rotational energy (up to $\\approx 29%$ of the total energy of the black hole) can be extracted.
Modified Black Hole with Polar Jet and Vortex
T. Tmmalm
2001-12-06T23:59:59.000Z
There are many models relating an accretion disk of Black Hole to jet outflow. The herein heuristic model describes the continuation of an external accretion disk to an internal accretion disk for less than Black Hole horizon, and subsequent polar jet outflow along polar axis out of polar vortex wherein the event horizon is no longer descriptive.
Particle Acceleration in Rotating Modified Hayward and Bardeen Black Holes
Behnam Pourhassan; Ujjal Debnath
2015-06-10T23:59:59.000Z
In this paper we consider rotating modified Hayward and Bardeen black holes as particle accelerators. We investigate the the center of mass energy of two colliding neutral particles with same rest masses falling from rest at infinity to near the horizons of the mentioned black holes. We also investigate the range of the particle's angular momentum and the orbit of the particle.
Particle Acceleration in Rotating Modified Hayward and Bardeen Black Holes
Pourhassan, Behnam
2015-01-01T23:59:59.000Z
In this paper we consider rotating modified Hayward and Bardeen black holes as particle accelerators. We investigate the the center of mass energy of two colliding neutral particles with same rest masses falling from rest at infinity to near the horizons of the mentioned black holes. We also investigate the range of the particle's angular momentum and the orbit of the particle.
Energy decomposition within Einstein-Born-Infeld black holes
Jonas P. Pereira; Jorge A. Rueda
2015-03-09T23:59:59.000Z
We analyze the consequences of the recently found generalization of the Christodoulou-Ruffini black hole mass decomposition for Einstein-Born-Infeld black holes [characterized by the parameters $(Q,M,b)$, where $M = M(M_{irr},Q,b)$, $b$ scale field, $Q$ charge, $M_{irr}$ "irreducible mass", physically meaning the energy of a black hole when its charge is null] and their interactions. We show in this context that their description is largely simplified and can basically be split into two families depending upon the parameter $b|Q|$. If $b|Q|\\leq 1/2$, then black holes could have even zero irreducible masses and they always exhibit single, non degenerated, horizons. If $b|Q|>1/2$, then an associated black hole must have a minimum irreducible mass (related to its minimum energy) and has two horizons up to a transitional irreducible mass. For larger irreducible masses, single horizon structures raise again. By assuming that black holes emit thermal uncharged scalar particles, we further show in light of the black hole mass decomposition that one satisfying $b|Q|>1/2$ takes an infinite amount of time to reach the zero temperature, settling down exactly at its minimum energy. Finally, we argue that depending on the fundamental parameter $b$, the radiation (electromagnetic and gravitational) coming from Einstein-Born-Infeld black holes could differ significantly from Einstein-Maxwell ones. Hence, it could be used to assess such a parameter.
Pair Production of Topological anti de Sitter Black Holes
R. B. Mann
1996-07-28T23:59:59.000Z
The pair creation of black holes with event horizons of non-trivial topology is described. The spacetimes are all limiting cases of the cosmological $C$ metric. They are generalizations of the $(2+1)$ dimensional black hole and have asymptotically anti de Sitter behaviour. Domain walls instantons can mediate their pair creation for a wide range of mass and charge.
Proton Hole States of Nb,95,97,99
Bindal, P. K.; Youngblood, David H.; Kozub, R. L.
1974-01-01T23:59:59.000Z
-lying proton hole states in the Nb isotopes is from the study of Ohnuma and Yntema. ' Our recent study of hole state analogs of Nb levels in the Mo iso- topes' revealed a dramatic drop in analog state strength, particularly for / =1 states as one pro...
Renyi entropies of a black hole from Hawking radiation
A. Bialas; W. Czyz
2008-01-30T23:59:59.000Z
Renyi entropies of a black hole are evaluated by counting the states of the Hawking radiation which fills a thin shell surrounding the horizon. The width of the shell is determined from its energy content and the corresponding mass defect. The Bekenstein-Hawking formula for the entropy of the black hole is correctly reproduced.
Structure and Mass Absorption of Hypothetical Terrestrial Black Holes
A. P. VanDevender; J. Pace VanDevender
2011-05-02T23:59:59.000Z
The prospect of mini black holes, either primordial or in planned experiments at the Large Hadron Collider, interacting with the earth motivate us to examine how they may be detected and the scope of their impact on the earth. We propose that the more massive of these objects may gravitationally bind matter without significant absorption. Since the wave functions of gravitationally bound atoms orbiting a black hole are analogous to those of electrons around a nucleus, we call such an object the Gravitationally Equivalent of an Atom (GEA). Mini black holes are expected to lose mass through quantum evaporation, which has become well accepted on purely theoretical grounds. Since all attempts to directly observe x-rays from an evaporating black hole have failed, we examine the possibility of the inverse test: search for extant mini black holes by looking for emissions from matter bound in a GEA. If quantum evaporation does not occur, then miniature black holes left over from the early universe may be stable, contribute to dark matter, and in principle be detectable through emissions associated with the bound matter. We show that small black holes-with masses below \\sim10^12 kg-can bind matter without readily absorbing it into the black hole but the emissions are too weak to be detected from earth.
Weighing Black Holes in high-z SCUBA Galaxies
Alexander, D M
2006-01-01T23:59:59.000Z
Deep SCUBA surveys have uncovered a population of dust-enshrouded star-forming galaxies at z~2. Using the ultra-deep 2 Ms Chandra Deep Field-North survey we recently showed that a large fraction of these systems are also undergoing intense black-hole growth. Here we provide further constraints on the properties of the black holes in SCUBA galaxies using the virial black-hole mass estimator. We show that typical SCUBA galaxies are likely to host black holes with M_BH~10^7-10^8 M_solar which are accreting at, or close to, the Eddington limit. These results provide qualitative support for our earlier conclusion that the growth of the black hole lags that of the host galaxy in these massive ultraluminous galaxies.
Quasinormal modes of test fields around regular black holes
Bobir Toshmatov; Ahmadjon Abdujabbarov; Zden?k Stuchlík; Bobomurat Ahmedov
2015-04-25T23:59:59.000Z
We study scalar, electromagnetic and gravitational test fields in the Hayward, Bardeen and Ay\\'on-Beato-Garc\\'ia regular black hole spacetimes and demonstrate that the test fields are stable in all these spacetimes. Using the sixth order WKB approximation of the linear "axial" perturbative scheme, we determine dependence of the quasinormal mode (QNM) frequencies on the characteristic parameters of the test fields and the spacetime charge parameters of the regular black holes. We give also the greybody factors, namely the transmission and reflection coefficients of scattered scalar, electromagnetic and gravitational waves. We show that damping of the QNMs in regular black hole spacetimes is suppressed in comparison to the case of Schwarzschild black holes, and increasing charge parameter of the regular black holes increases reflection and decreases transmission factor of incident waves for each of the test fields.
Black Holes are neither Particle Accelerators nor Dark Matter Probes
Sean T. McWilliams
2012-12-06T23:59:59.000Z
It has been suggested that maximally spinning black holes can serve as particle accelerators, reaching arbitrarily high center-of-mass energies. Despite several objections regarding the practical achievability of such high energies, and demonstrations past and present that such large energies could never reach a distant observer, interest in this problem has remained substantial. We show that, unfortunately, a maximally spinning black hole can never serve as a probe of high energy collisions, even in principle and despite the correctness of the original diverging energy calculation. Black holes can indeed facilitate dark matter annihilation, but the most energetic photons can carry little more than the rest energy of the dark matter particles to a distant observer, and those photons are actually generated relatively far from the black hole where relativistic effects are negligible. Therefore, any strong gravitational potential could probe dark matter equally well, and an appeal to black holes for facilitating such collisions is unnecessary.
Quasinormal modes of test fields around regular black holes
Bobir Toshmatov; Ahmadjon Abdujabbarov; Zden?k Stuchlík; Bobomurat Ahmedov
2015-03-19T23:59:59.000Z
We study scalar, electromagnetic and gravitational test fields in the Hayward, Bardeen and Ay\\'{o}n-Beato-Garc\\'{i}a regular black hole spacetimes and demonstrate that the test fields are stable in all these spacetimes. Using the sixth order WKB approximation of the linear "axial" perturbative scheme, we determine dependence of the quasinormal mode (QNM) frequencies on the characteristic parameters of the test fields and the spacetime charge parameters of the regular black holes. We give also the greybody factors, namely the transmission and reflection coefficients of scattered scalar, electromagnetic and gravitational waves. We show that damping of the QNMs in regular black hole spacetimes is suppressed in comparison to the case of Schwarzschild black holes, and increasing charge parameter of the regular black holes increases reflection and decreases transmission factor of incident waves for each of the test fields.
Implications of a viscosity bound on black hole accretion
Aninda Sinha; Banibrata Mukhopadhyay
2012-02-13T23:59:59.000Z
Motivated by the viscosity bound in gauge/gravity duality, we consider the ratio of shear viscosity (eta) to entropy density (s) in black hole accretion flows. We use both an ideal gas equation of state and the QCD equation of state obtained from lattice for the fluid accreting onto a Kerr black hole. The QCD equation of state is considered since the temperature of accreting matter is expected to approach 10^{12}K in certain hot flows. We find that in both the cases eta/s is small only for primordial black holes and several orders of magnitude larger than any known fluid for stellar and supermassive black holes. We show that a lower bound on the mass of primordial black holes leads to a lower bound on eta/s and vice versa. Finally we speculate that the Shakura-Sunyaev viscosity parameter should decrease with increasing density and/or temperatures.
Black Hole Hair Removal: Non-linear Analysis
Dileep P. Jatkar; Ashoke Sen; Yogesh K. Srivastava
2009-07-03T23:59:59.000Z
BMPV black holes in flat transverse space and in Taub-NUT space have identical near horizon geometries but different microscopic degeneracies. It has been proposed that this difference can be accounted for by different contribution to the degeneracies of these black holes from hair modes, -- degrees of freedom living outside the horizon. In this paper we explicitly construct the hair modes of these two black holes as finite bosonic and fermionic deformations of the black hole solution satisfying the full non-linear equations of motion of supergravity and preserving the supersymmetry of the original solutions. Special care is taken to ensure that these solutions do not have any curvature singularity at the future horizon when viewed as the full ten dimensional geometry. We show that after removing the contribution due to the hair degrees of freedom from the microscopic partition function, the partition functions of the two black holes agree.
C. Tadhunter; A. Marconi; D. Axon; K. Wills; T. G. Robinson; N. Jackson
2003-02-25T23:59:59.000Z
We use a combination of high spatial resolution optical and near-IR spectroscopic data to make a detailed study of the kinematics of the NLR gas in the near-nuclear regions of the powerful, FRII radio galaxy Cygnus A (z=0.0560), with the overall goal of placing limits on the mass of any supermassive black hole in the core. Our K-band infrared observations (0.75 arcsec seeing) -- taken with NIRSPEC on the Keck II telescope -- show a smooth rotation pattern across the nucleus in the Paschen alpha and H_2 emission lines along a slit position (PA180) close to perpendicular to the radio axis, however, there is no evidence for such rotation along the radio axis (PA105). Higher spatial resolution observations of the [OIII]5007 emission line -- taken with STIS on the Hubble Space Telescope (HST) -- confirm the general rotation pattern of the gas in the direction perpendicular to the radio axis, and provide evidence for steep velocity gradients within a radius of 0.1 arcsec of the core. The circular velocities measured from both the Keck and HST data lead to an estimate of the mass of the supermassive black hole of 2.5+/-0.7x10^9 solar masses. For the host galaxy properties of Cygnus A, this mass is consistent with the global correlations between black hole mass and host galaxy properties deduced for non-active galaxies. Therefore, despite the extreme power of its radio source and the quasar-like luminosity of its AGN, the black hole in Cygnus A is not unusually massive considering theluminosity of its host galaxy. Indeed, the estimated mass of the black hole in Cygnus A is similar to that inferred for the supermassive black hole in the FRI radio galaxy M87, despite the fact that the AGN and radio jets of Cygnus A are 2 -- 3 orders of magnitude more powerful.
Kerr black hole parameters in terms of red/blue shifts of photons emitted by geodesic particles
Alfredo Herrera-Aguilar; Ulises Nucamendi
2015-06-17T23:59:59.000Z
We are motivated by the recently reported dynamical evidence of stars with short orbital periods moving around the center of the Milky Way and the corresponding hypothesis about the existence of a supermassive black hole hosted at its center. In this paper we show how the mass and rotation parameters of a Kerr black hole (assuming that the putative supermassive black hole is of this type), as well as the distance that separates the black hole from the Earth, can be estimated in a relativistic way in terms of i) the red and blue shifts of photons that are emitted by geodesic massive particles (stars and galactic gas) and travel along null geodesics towards a distant observer, and ii) the radius of these star/gas orbits. As a concrete example and as a first step towards a full relativistic analysis of the above mentioned star orbits around the center of our galaxy, we consider stable equatorial circular orbits of stars and express their corresponding red/blue shifts in terms of the metric parameters (mass and angular momentum per unit mass) and the orbital radii of both the emitter star (and/or galactic gas) and the distant observer. In principle, these expressions allow one to statistically estimate the mass and rotation parameters of the Kerr black hole, and the radius of our orbit, through a Bayesian fitting, i.e., with the aid of observational data: the red/blue shifts measured at certain points of stars' orbits and their radii, with their respective errors, a task that we hope to perform in the near future. We also point to several astrophysical phenomena, like accretion discs of rotating black holes, binary systems and active galactic nuclei, among others, to which this formalism can be applied.
UNIVERSAL BEHAVIOR OF X-RAY FLARES FROM BLACK HOLE SYSTEMS
Wang, F. Y.; Dai, Z. G.; Yi, S. X. [School of Astronomy and Space Science, Nanjing University, Nanjing 210093 (China); Xi, S. Q., E-mail: fayinwang@nju.edu.cn, E-mail: dzg@nju.edu.cn [Department of Physics and GXU-NAOC Center for Astrophysics and Space Sciences, Guangxi University, Nanning 530004 (China)
2015-01-01T23:59:59.000Z
X-ray flares have been discovered in black hole systems such as gamma-ray bursts, the tidal disruption event Swift J1644+57, the supermassive black hole Sagittarius A* at the center of our Galaxy, and some active galactic nuclei. Occurrences of X-ray flares are always accompanied by relativistic jets. However, it is still unknown whether or not there is a physical analogy among such X-ray flares produced in black hole systems spanning nine orders of magnitude in mass. Here, we report observed data of X-ray flares and show that they have three statistical properties similar to solar flares, including power-law distributions of their energies, durations, and waiting times, which can be explained by a fractal-diffusive, self-organized criticality model. These statistical similarities, together with the fact that solar flares are triggered by a magnetic reconnection process, suggest that all of the X-ray flares are consistent with magnetic reconnection events, implying that their concomitant relativistic jets may be magnetically dominated.
Universal Behavior of X-ray Flares from Black Hole Systems
Wang, F Y; Yi, S X; Xi, S Q
2014-01-01T23:59:59.000Z
X-ray flares have been discovered in black hole systems, such as gamma-ray bursts, the tidal disruption event Swift J1644+57, the supermassive black hole Sagittarius A$^*$ at the center of our Galaxy, and some active galactic nuclei. Their occurrences are always companied by relativistic jets. However, it is still unknown whether there is a physical analogy among such X-ray flares produced in black hole systems spanning nine orders of magnitude in mass. Here we report the observed data of X-ray flares, and show that they have three statistical properties similar to solar flares, including power-law distributions of energies, durations, and waiting times, which both can be explained by a fractal-diffusive self-organized criticality model. These statistical similarities, together with the fact that solar flares are triggered by a magnetic reconnection process, suggest that all of the X-ray flares are consistent with magnetic reconnection events, implying that their concomitant relativistic jets may be magnetica...
Most supermassive black hole growth is obscured by dust
Alejo Martinez-Sansigre; Steve Rawlings; Mark Lacy; Dario Fadda; Francine R. Marleau; Chris Simpson; Chris J. Willott; Matt J. Jarvis
2005-09-18T23:59:59.000Z
We present an alternative method to X-ray surveys for hunting down the high-redshift type-2 quasar population, using Spitzer and VLA data on the Spitzer First Look Survey. By demanding objects to be bright at 24 microns but faint at 3.6 microns, and combining this with a radio criterion, we find 21 type-2 radio-quiet quasar candidates at the epoch at which the quasar activity peaked. Optical spectroscopy with the WHT confirmed 10 of these objects to be type-2s with 1.4 < z < 4.2 while the rest are blank. There is no evidence for contamination in our sample, and we postulate that our 11 blank-spectrum candidates are obscured by kpc-scale dust as opposed to dust from a torus around the accretion disk. By carefully modelling our selection criteria, we conclude that, at high redshift, 50-80 % of the supermassive black hole growth is obscured by dust.
Horizon dynamics of distorted rotating black holes
Tony Chu; Harald P. Pfeiffer; Michael I. Cohen
2011-04-28T23:59:59.000Z
We present numerical simulations of a Kerr black hole perturbed by a pulse of ingoing gravitational radiation. For strong perturbations we find up to five concentric marginally outer trapped surfaces. These trapped surfaces appear and disappear in pairs, so that the total number of such surfaces at any given time is odd. The world tubes traced out by the marginally outer trapped surfaces are found to be spacelike during the highly dynamical regime, approaching a null hypersurface at early and late times. We analyze the structure of these marginally trapped tubes in the context of the dynamical horizon formalism, computing the expansion of outgoing and incoming null geodesics, as well as evaluating the dynamical horizon flux law and the angular momentum flux law. Finally, we compute the event horizon. The event horizon is well-behaved and approaches the apparent horizon before and after the highly dynamical regime. No new generators enter the event horizon during the simulation.
Collisions with Black Holes and Deconfined Plasmas
Amsel, Aaron J; Virmani, Amitabh
2008-01-01T23:59:59.000Z
We use AdS/CFT to investigate i) high energy collisions with balls of deconfined plasma surrounded by a confining phase and ii) the rapid localized heating of a deconfined plasma. Both of these processes are dual to collisions with black holes, where they result in the nucleation of a new "arm" of the horizon reaching out in the direction of the incident object. We study the resulting non-equilibrium dynamics in a universal limit of the gravitational physics which may indicate universal behavior of deconfined plasmas at large N_c. Process (i) produces "virtual" arms of the plasma ball, while process (ii) can nucleate surprisingly large bubbles of a higher temperature phase.
Collisions with Black Holes and Deconfined Plasmas
Aaron J. Amsel; Donald Marolf; Amitabh Virmani
2007-12-13T23:59:59.000Z
We use AdS/CFT to investigate i) high energy collisions with balls of deconfined plasma surrounded by a confining phase and ii) the rapid localized heating of a deconfined plasma. Both of these processes are dual to collisions with black holes, where they result in the nucleation of a new "arm" of the horizon reaching out in the direction of the incident object. We study the resulting non-equilibrium dynamics in a universal limit of the gravitational physics which may indicate universal behavior of deconfined plasmas at large N_c. Process (i) produces "virtual" arms of the plasma ball, while process (ii) can nucleate surprisingly large bubbles of a higher temperature phase.
Absolute conservation law for black holes
D. Grumiller; W. Kummer
1999-11-08T23:59:59.000Z
In all 2d theories of gravity a conservation law connects the (space-time dependent) mass aspect function at all times and all radii with an integral of the matter fields. It depends on an arbitrary constant which may be interpreted as determining the initial value together with the initial values for the matter field. We discuss this for spherically reduced Einstein-gravity in a diagonal metric and in a Bondi-Sachs metric using the first order formulation of spherically reduced gravity, which allows easy and direct fixations of any type of gauge. The relation of our conserved quantity to the ADM and Bondi mass is investigated. Further possible applications (ideal fluid, black holes in higher dimensions or AdS spacetimes etc.) are straightforward generalizations.
The (Unstable) Threshold of Black Hole Formation
M. W. Choptuik
1998-03-23T23:59:59.000Z
In recent years it has become apparent that intriguing phenomenology exists at the threshold of black hole formation in a large class of general relativistic collapse models. This phenomenology, which includes scaling, self-similarity and universality, is largely analogous to statistical mechanical critical behaviour, a fact which was first noted empirically, and subsequently clarified by perturbative calculations which borrow on ideas and techniques from dynamical systems theory and renormalization group theory. This contribution, which closely parallels my talk at the conference, consists of an overview of the considerable ``zoo''' of critical solutions which have been discovered thus far, along with a brief discussion of how we currently understand the nature of these solutions from the point of view of perturbation theory.
Black Hole Attractors and Pure Spinors
Hsu, Jonathan P.; Maloney, Alexander; Tomasiello, Alessandro
2006-02-21T23:59:59.000Z
We construct black hole attractor solutions for a wide class of N = 2 compactifications. The analysis is carried out in ten dimensions and makes crucial use of pure spinor techniques. This formalism can accommodate non-Kaehler manifolds as well as compactifications with flux, in addition to the usual Calabi-Yau case. At the attractor point, the charges fix the moduli according to {Sigma}f{sub k} = Im(C{Phi}), where {Phi} is a pure spinor of odd (even) chirality in IIB (A). For IIB on a Calabi-Yau, {Phi} = {Omega} and the equation reduces to the usual one. Methods in generalized complex geometry can be used to study solutions to the attractor equation.
Modeling the black hole excision problem
Szilagyi, B.; Winicour, J. [Department of Physics and Astronomy, University of Pittsburgh, Pittsburgh, Pennsylvania 15260 (United States); Albert Einstein Institute, Max Planck Gesellschaft, Am Muehlenberg 1, D-14476 Golm (Germany); Kreiss, H.-O. [Albert Einstein Institute, Max Planck Gesellschaft, Am Muehlenberg 1, D-14476 Golm (Germany); NADA, Royal Institute of Technology, 10044 Stockholm (Sweden)
2005-05-15T23:59:59.000Z
We analyze the excision strategy for simulating black holes. The problem is modeled by the propagation of quasilinear waves in a 1-dimensional spatial region with timelike outer boundary, spacelike inner boundary and a horizon in between. Proofs of well-posed evolution and boundary algorithms for a second differential order treatment of the system are given for the separate pieces underlying the finite-difference problem. These are implemented in a numerical code which gives accurate long term simulations of the quasilinear excision problem. Excitation of long wavelength exponential modes, which are latent in the problem, are suppressed using conservation laws for the discretized system. The techniques are designed to apply directly to recent codes for the Einstein equations based upon the harmonic formulation.
Generalized uncertainty principle and black hole thermodynamics
Sunandan Gangopadhyay; Abhijit Dutta; Anirban Saha
2014-01-08T23:59:59.000Z
We study the Schwarzschild and Reissner-Nordstr\\"{o}m black hole thermodynamics using the simplest form of the generalized uncertainty principle (GUP) proposed in the literature. The expressions for the mass-temperature relation, heat capacity and entropy are obtained in both cases from which the critical and remnant masses are computed. Our results are exact and reveal that these masses are identical and larger than the so called singular mass for which the thermodynamics quantities become ill-defined. The expression for the entropy reveals the well known area theorem in terms of the horizon area in both cases upto leading order corrections from GUP. The area theorem written in terms of a new variable which can be interpreted as the reduced horizon area arises only when the computation is carried out to the next higher order correction from GUP.
Higgs Boson Production from Black Holes at the LHC
Gouranga C. Nayak; J. Smith
2006-06-09T23:59:59.000Z
If the fundamental Planck scale is near a TeV, then TeV scale black holes should be produced in proton-proton collisions at the LHC where \\sqrt{s} = 14 TeV. As the temperature of the black holes can be ~ 1 TeV we also expect production of Higgs bosons from them via Hawking radiation. This is a different production mode for the Higgs boson, which would normally be produced via direct pQCD parton fusion processes. In this paper we compare total cross sections and transverse momentum distributions d\\sigma/dp_T for Higgs production from black holes at the LHC with those from direct parton fusion processes at next-to-next-to-leading order and next-to-leading order respectively. We find that the Higgs production from black holes can be larger or smaller than the direct pQCD production depending upon the Planck mass and black hole mass. We also find that d\\sigma/dp_T of Higgs production from black holes increases as a function of p_T which is in sharp contrast with the pQCD predictions where d\\sigma/dp_T decreases so we suggest that the measurement of an increase in d\\sigma/dp_T as p_T increases for Higgs (or any other heavy particle) production can be a useful signature for black holes at the LHC.
Simulating merging binary black holes with nearly extremal spins
Lovelace, Geoffrey [Center for Radiophysics and Space Research, Cornell University, Ithaca, New York, 14853 (United States); Scheel, Mark A.; Szilagyi, Bela [Theoretical Astrophysics 350-17, California Institute of Technology, Pasadena, California 91125 (United States)
2011-01-15T23:59:59.000Z
Astrophysically realistic black holes may have spins that are nearly extremal (i.e., close to 1 in dimensionless units). Numerical simulations of binary black holes are important tools both for calibrating analytical templates for gravitational-wave detection and for exploring the nonlinear dynamics of curved spacetime. However, all previous simulations of binary-black-hole inspiral, merger, and ringdown have been limited by an apparently insurmountable barrier: the merging holes' spins could not exceed 0.93, which is still a long way from the maximum possible value in terms of the physical effects of the spin. In this paper, we surpass this limit for the first time, opening the way to explore numerically the behavior of merging, nearly extremal black holes. Specifically, using an improved initial-data method suitable for binary black holes with nearly extremal spins, we simulate the inspiral (through 12.5 orbits), merger and ringdown of two equal-mass black holes with equal spins of magnitude 0.95 antialigned with the orbital angular momentum.
Quantum-Gravity Fluctuations and the Black-Hole Temperature
Hod, Shahar
2015-01-01T23:59:59.000Z
Bekenstein has put forward the idea that, in a quantum theory of gravity, a black hole should have a discrete energy spectrum with concomitant discrete line emission. The quantized black-hole radiation spectrum is expected to be very different from Hawking's semi-classical prediction of a thermal black-hole radiation spectrum. One naturally wonders: Is it possible to reconcile the {\\it discrete} quantum spectrum suggested by Bekenstein with the {\\it continuous} semi-classical spectrum suggested by Hawking ? In order to address this fundamental question, in this essay we shall consider the zero-point quantum-gravity fluctuations of the black-hole spacetime. In a quantum theory of gravity, these spacetime fluctuations are closely related to the characteristic gravitational resonances of the corresponding black-hole spacetime. Assuming that the energy of the black-hole radiation stems from these zero-point quantum-gravity fluctuations of the black-hole spacetime, we derive the effective temperature of the quanti...
Following Black Hole Scaling Relations Through Gas-Rich Mergers
Medling, Anne M; Max, Claire E; Sanders, David B; Armus, Lee; Holden, Bradford; Mieda, Etsuko; Wright, Shelley A; Larkin, James E
2015-01-01T23:59:59.000Z
We present black hole mass measurements from kinematic modeling of high-spatial resolution integral field spectroscopy of the inner regions of 9 nearby (ultra-)luminous infrared galaxies in a variety of merger stages. These observations were taken with OSIRIS and laser guide star adaptive optics on the Keck I and Keck II telescopes, and reveal gas and stellar kinematics inside the spheres of influence of these supermassive black holes. We find that this sample of black holes are overmassive ($\\sim10^{7-9}$ M$_{Sun}$) compared to the expected values based on black hole scaling relations, and suggest that the major epoch of black hole growth occurs in early stages of a merger, as opposed to during a final episode of quasar-mode feedback. The black hole masses presented are the dynamical masses enclosed in $\\sim$25pc, and could include gas which is gravitationally bound to the black hole but has not yet lost sufficient angular momentum to be accreted. If present, this gas could in principle eventually fuel AGN f...
Black Holes with Primary Hair in gauged N=8 Supergravity
Andres Anabalon; Fabrizio Canfora; Alex Giacomini; Julio Oliva
2012-03-29T23:59:59.000Z
In this paper, we analyze the static solutions for the $U(1)^{4}$ consistent truncation of the maximally supersymmetric gauged supergravity in four dimensions. Using a new parametrization of the known solutions it is shown that for fixed charges there exist three possible black hole configurations according to the pattern of symmetry breaking of the (scalars sector of the) Lagrangian. Namely a black hole without scalar fields, a black hole with a primary hair and a black hole with a secondary hair respectively. This is the first, exact, example of a black hole with a primary scalar hair, where both the black hole and the scalar fields are regular on and outside the horizon. The configurations with secondary and primary hair can be interpreted as a spontaneous symmetry breaking of discrete permutation and reflection symmetries of the action. It is shown that there exist a triple point in the thermodynamic phase space where the three solution coexist. The corresponding phase transitions are discussed and the free energies are written explicitly as function of the thermodynamic coordinates in the uncharged case. In the charged case the free energies of the primary hair and the hairless black hole are also given as functions of the thermodynamic coordinates.
No-hair theorem for Black Holes in Astrophysical Environments
Gürlebeck, Norman
2015-01-01T23:59:59.000Z
According to the no-hair theorem, static black holes are described by a Schwarzschild spacetime provided there are no other sources of the gravitational field. This requirement, however, is in astrophysical realistic scenarios often violated, e.g., if the black hole is part of a binary system or if it is surrounded by an accretion disk. In these cases, the black hole is distorted due to tidal forces. Nonetheless, the subsequent formulation of the no-hair theorem holds: The contribution of the distorted black hole to the multipole moments that describe the gravitational field close to infinity and, thus, all sources is that of a Schwarzschild black hole. It still has no hair. This implies that there is no multipole moment induced in the black hole and that its second Love numbers, which measure some aspects of the distortion, vanish as was already shown in approximations to general relativity. But here we prove this property for astrophysical relevant black holes in full general relativity.
Powerful Outflows and Feedback from Active Galactic Nuclei
King, Andrew
2015-01-01T23:59:59.000Z
Active Galactic Nuclei (AGN) represent the growth phases of the supermassive black holes in the center of almost every galaxy. Powerful, highly ionized winds, with velocities $\\sim 0.1- 0.2c$ are a common feature in X--ray spectra of luminous AGN, offering a plausible physical origin for the well known connections between the hole and properties of its host. Observability constraints suggest that the winds must be episodic, and detectable only for a few percent of their lifetimes. The most powerful wind feedback, establishing the $M -\\sigma$ relation, is probably not directly observable at all. The $M - \\sigma$ relation signals a global change in the nature of AGN feedback. At black hole masses below $M-\\sigma$ feedback is confined to the immediate vicinity of the hole. At the $M-\\sigma$ mass it becomes much more energetic and widespread, and can drive away much of the bulge gas as a fast molecular outflow.
Scalar emission in a rotating Gödel black hole
Songbai Chen; Bin Wang; Jiliang Jing
2008-08-23T23:59:59.000Z
We study the absorption probability and Hawking radiation of the scalar field in the rotating G\\"{o}del black hole in minimal five-dimensional gauged supergravity. We find that G\\"{o}del parameter $j$ imprints in the greybody factor and Hawking radiation. It plays a different role from the angular momentum of the black hole in the Hawking radiation and super-radiance. These information can help us know more about rotating G\\"{o}del black holes in minimal five-dimensional gauged supergravity.
The r-Process in Black Hole Winds
Shinya Wanajo; Hans-Thomas Janka
2010-06-11T23:59:59.000Z
All the current r-process scenarios relevant to core-collapse supernovae are facing severe difficulties. In particular, recent core-collapse simulations with neutrino transport show no sign of a neutron-rich wind from the proto-neutron star. In this paper, we discuss nucleosynthesis of the r-process in an alternative astrophysical site, "black hole winds", which are the neutrino-driven outflow from the accretion torus around a black hole. This condition is assumed to be realized in double neutron star mergers, neutron star - black hole mergers, or hypernovae.
Thermodynamics of an Evaporating Schwarzschild Black Hole in Noncommutative Space
Kourosh Nozari; Behnaz Fazlpour
2007-01-14T23:59:59.000Z
We investigate the effects of space noncommutativity and the generalized uncertainty principle on the thermodynamics of a radiating Schwarzschild black hole. We show that evaporation process is in such a way that black hole reaches to a maximum temperature before its final stage of evolution and then cools down to a nonsingular remnant with zero temperature and entropy. We compare our results with more reliable results of string theory. This comparison Shows that GUP and space noncommutativity are similar concepts at least from view point of black hole thermodynamics.
From Special Geometry to Black Hole Partition Functions
Thomas Mohaupt
2008-12-22T23:59:59.000Z
These notes are based on lectures given at the Erwin-Schrodinger Insitut in Vienna in 2006/07 and at the 2007 School on Attractor Mechanism in Frascati. Lecture I: special geometry from the superconformal point of view. Lecture II: black hole attractor mechanism, its underlying variational principle, and black hole partition functions. Lecture III: large and small BPS black holes in N=4 supergravity. Lecture IV: state counting for N=4 string compactifications. Appendix A: special geometry from the mathematical point of view. Appendix B: review of modular forms. Contains four problems which allow the readers to develop some of the key concepts by themselves.
Non-extremal Kerr black holes as particle accelerators
Sijie Gao; Changchun Zhong
2011-08-03T23:59:59.000Z
It has been shown that extremal Kerr black holes can be used as particle accelerators and arbitrarily high energy may be obtained near the event horizon. We study particle collisions near the event horizon (outer horizon) and Cauchy horizon (inner horizon) of a non-extremal Kerr black hole. Firstly, we provide a general proof showing that particles cannot collide with arbitrarily high energies at the outter horizon. Secondly, we show that ultraenergetic collisions can occur near the inner horizon of a Kerr black hole with any spin parameter $a$.
Acceleration of particles in Einstein-Maxwell-Dilaton black hole
Pu-Jian Mao; Ran Li; Lin-Yu Jia; Ji-Rong Ren
2011-03-08T23:59:59.000Z
It has been recently pointed out that, under certain conditions, the energy of particles accelerated by black holes in the center-of-mass frame can become arbitrarily high. In this Letter, we study the collision of two particles around the four-dimensional Kaluza-Klein black hole in Einstein-Maxwell-Dilaton theory. We find that the center-of-mass energy for a pair of colliding particles is unlimited at the horizon of charged nonrotating and extremal rotating Kaluza-Klein black hole.
String black hole: Can it be a particle accelerator ?
Sharmanthie Fernando
2014-08-21T23:59:59.000Z
In this paper we have studied the possibility of the center-of-mass energy of two particles colliding near the horizon of a static charged black hole in string theory. Various cases corresponding to the electric charge and the angular momentum of the particles were considered. The studies were done for the general black hole as well as for the extreme black hole. There were two scenarios where the center-of-mass energy reach very large values if the appropriate properties of the particles are chosen.
Inferring black hole charge from backscattered electromagnetic radiation
Luís C. B. Crispino; Sam R. Dolan; Atsushi Higuchi; Ednilton S. de Oliveira
2014-09-16T23:59:59.000Z
We compute the scattering cross section of Reissner-Nordstr\\"om black holes for the case of an incident electromagnetic wave. We describe how scattering is affected by both the conversion of electromagnetic to gravitational radiation, and the parity-dependence of phase shifts induced by the black hole charge. The latter effect creates a helicity-reversed scattering amplitude that is non-zero in the backward direction. We show that from the character of the electromagnetic wave scattered in the backward direction it is possible, in principle, to infer if a static black hole is charged.
Accretion onto a black hole in a string cloud background
Apratim Ganguly; Sushant G. Ghosh; Sunil D. Maharaj
2014-09-28T23:59:59.000Z
We examine the accretion process onto the black hole with a string cloud background, where the horizon of the black hole has an enlarged radius $r_H=2 M/(1-\\alpha)$, due to the string cloud parameter $\\alpha\\; (0 \\leq \\alpha cloud parameter $\\alpha$. We also find the gas compression ratios and temperature profiles below the accretion radius and at the event horizon. It is shown that the mass accretion rate, for both the relativistic and the non-relativistic fluid by a black hole in the string cloud model, increases with increase in $\\alpha$.
Rotating charged cylindrical black holes as particle accelerators
Said, Jackson Levi [Physics Department, University of Malta, Msida MSD 2080 (Malta); Adami, Kristian Zarb [Physics Department, University of Malta, Msida MSD 2080 (Malta); Physics Department, University of Oxford, Oxford, OX1 3RH (United Kingdom)
2011-05-15T23:59:59.000Z
It has recently been pointed out that arbitrary center-of-mass energies may be obtained for particle collisions near the horizon of an extremal Kerr black hole. We investigate this mechanism in cylindrical topology. In particular we consider the center-of-mass energies of a cylindrical black hole with an extremal rotation and charge parameter. The geodesics are first derived with a rotating charged cylindrical black hole producing the background gravitational field. Finally the center-of-mass is determined for this background and its extremal limit is taken.
Black holes and the absorption rate of cosmological scalar fields
L. Arturo Urena-Lopez; Lizbeth M. Fernandez
2011-07-15T23:59:59.000Z
We study the absorption of a massless scalar field by a static black hole. Using the continuity equation that arises from the Klein-Gordon equation, it is possible to define a normalized absorption rate $\\Gamma(t)$ for the scalar field as it falls into the black hole. It is found that the absorption mainly depends upon the characteristics wavelengths involved in the physical system: the mean wavenumber and the width of the wave packet, but that it is insensitive to the scalar field's strength. By taking a limiting procedure, we determine the minimum absorption fraction of the scalar field's mass by the black hole, which is around 50%.
Rotordynamic evaluation of frequency dependent impedances of hole-pattern gas damper seals
Holt, Christopher George
2000-01-01T23:59:59.000Z
Two hole-pattern seals are compared with one smooth bore seal. The two hole-pattern seals have cell depths of 2.03 mm and 3.18 mm with a cell diameter of 1.59 mm. The hole area density factor for both hole-pattern seals is 43%. The L/D ratio...
Helmick, C.; Koczan, S.; Pettitt, R.
1982-04-01T23:59:59.000Z
During the preceding work (Phase I) of the Hot Dry Rock (HDR) Geothermal Energy Project at Fenton Hill, two holes were drilled to a depth of nearly 3048 m (10,000 ft) and connected by a vertical hydraulic fracture. In this phase, water was pumped through the underground reservoir for approximately 417 days, producing an energy equivalent of 3 to 5 MW(t). Energy Extraction Hole No. 2 (EE-2) is the first of two deep holes that will be used in the Engineering-Resource Development System (Phase II) of the ongoing HDR Project of the Los Alamos National Laboratory. This phase of the work consists of drilling two parallel boreholes, inclined in their lower, open-hole sections at 35/sup 0/ to the vertical and separated by a vertical distance of 366 m (1200 ft) between the inclined parts of the drill holes. The holes will be connected by a series of vertical, hydraulically produced fractures in the Precambrian granitic rock complex. EE-2 was drilled to a depth of 4660 m (15,289 ft), where the bottom-hole temperature is approximately 320/sup 0/C (608/sup 0/F). Directional drilling techniques were used to control the azimuth and deviation of the hole. Upgrading of the temperature capability of existing hardware, and development of new equipment was necessary to complete the drilling of the hole in the extremely hot, hard, and abrasive granitic formation. The drilling history and the problems with bits, directional tools, tubular goods, cementing, and logging are described. A discussion of the problems and recommendations for overcoming them are also presented.
Impact of heavy hole-light hole coupling on optical selection rules in GaAs quantum dots
Belhadj, T.; Amand, T.; Kunz, S.; Marie, X.; Urbaszek, B. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); Kunold, A. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); Departamento de Ciencias Basicas, UAM-A, Col. Reynosa Tamaulipas, 02200 Mexico D.F. (Mexico); Simon, C.-M. [INSA-CNRS-UPS, LPCNO, Universite de Toulouse, 135 Av. Rangueil, 31077 Toulouse (France); CNRS-UPS, LCAR, IRSAMC, Universite de Toulouse, 31062 Toulouse (France); Kuroda, T.; Abbarchi, M.; Mano, T.; Sakoda, K. [National Institute for Material Science, Namiki 1-1, Tsukuba 305-0044 (Japan)
2010-08-02T23:59:59.000Z
We report strong heavy hole-light hole mixing in GaAs quantum dots grown by droplet epitaxy. Using the neutral and charged exciton emission as a monitor we observe the direct consequence of quantum dot symmetry reduction in this strain free system. By fitting the polar diagram of the emission with simple analytical expressions obtained from k{center_dot}p theory we are able to extract the mixing that arises from the heavy-light hole coupling due to the geometrical asymmetry of the quantum dot.
Statistics of black hole radiance and the horizon area spectrum
Bekenstein, Jacob D
2015-01-01T23:59:59.000Z
The statistical response of a Kerr black hole to incoming quantum radiation has heretofore been studied by the methods of maximum entropy or quantum field theory in curved spacetime. Neither approach pretends to take into account the quantum structure of the black hole itself. To address this last issue we calculate here the conditional probability distribution associated with the hole's response by assuming that the horizon area has a discrete quantum spectrum, and that its quantum evolution corresponds to jumps between adjacent area eigenvalues, possibly occurring in series, with consequent emission or absorption of quanta, possibly in the same mode. This "atomic" model of the black hole is implemented in two different ways and recovers the previously calculated radiation statistics in both cases. The corresponding conditional probably distribution is here expressed in closed form in terms of an hypergeometric function.
The Energy for 2+1 Dimensional Black Hole Solutions
I-Ching Yang; Irina Radinschi
2006-11-05T23:59:59.000Z
The energy distributions of four 2+1 dimensional black hole solutions were obtained by using the Einstein and M{\\o}ller energy-momentum complexes. while $r \\to \\infty$, the energy distributions of these four solutions become divergence.
Energy Distribution of a Stringy Charged Black Hole
Ragab M. Gad
2003-06-22T23:59:59.000Z
The energy distribution associated with a stringy charged black hole is studied using M{\\o}ller's energy-momentum complex. Our result is reasonable and it differs from that known in literature using Einstein's energy-momentum complex.
Energy of a Conformal Scalar Dyon Black Hole
Irina Radinschi
2000-10-25T23:59:59.000Z
We obtain the energy of a conformal scalar dyon black hole (CSD) by using the energy-momentum complexes of Tolman and M{\\o}ller. The total gravitational energy is given by the CSD charge in the both prescriptions.
Black holes and the quark-gluon plasma
George Siopsis
2009-01-26T23:59:59.000Z
I discuss the possibility that the quark-gluon plasma at strong coupling admits a description in terms of a black hole in asymptotically anti-de Sitter space.
Inertial blob-hole symmetry breaking in magnetised plasma filaments
Kendl, Alexander
2015-01-01T23:59:59.000Z
Symmetry breaking between the propagation velocities of magnetised plasma filaments with large positive (blob) and negative (hole) amplitudes, as implied by a dimensional analysis scaling, is studied with global ("full-n") non-Boussinesq gyrofluid computations, which include finite inertia effects through nonlinear polarisation. Interchange blobs on a flat density background have higher inertia and propagate more slowly than holes. In the presence of a large enough density gradient, the effect is reversed: blobs accelerate down the gradient and holes are slowed in their propagation up the gradient. Drift wave blobs spread their initial vorticity rapidly into a fully developed turbulent state, whereas primary holes can remain coherent for many eddy turnover times. The results bear implications for plasma edge zonal flow evolution and tokamak scrape-off-layer transport.
Selected Data from Continental Scientific Drilling Core Holes...
Selected Data from Continental Scientific Drilling Core Holes VC-1 and VC-2A, Valles Caldera, New Mexico Jump to: navigation, search OpenEI Reference LibraryAdd to library Report:...
New Coordinate Systems for Axisymmetric Black Hole Collisions
P. Anninos; S. R. Brandt; P. Walker
1997-12-10T23:59:59.000Z
We describe a grid generation procedure designed to construct new classes of orthogonal coordinate systems for binary black hole spacetimes. The computed coordinates offer an alternative approach to current methods, in addition to providing a framework for potentially more stable and accurate evolutions of colliding black holes. As a particular example, we apply our procedure to generate appropriate numerical grids to evolve Misner's axisymmetric initial data set representing two equal mass black holes colliding head-on. These new results are compared with previously published calculations, and we find generally good agreement in both the waveform profiles and total radiated energies over the allowable range of separation parameters. Furthermore, because no specialized treatment of the coordinate singularities is required, these new grids are more easily extendible to unequal mass and spinning black hole collisions.
General solutions for thermopiezoelectrics with various holes under thermal loading
Qin, Qinghua
induced by thermal loads. The loads may be uniform remote heat Â¯ow, point heat source and temperature elastic plate with an hole of various shapes subjected to remote uniform mechanical loading. For plane
Core Holes At Valles Caldera - Sulphur Springs Geothermal Area...
Dennis L. Nielson, Pisto Larry, C.W. Criswell, R. Gribble, K. Meeker, J.A. Musgrave, T. Smith, D. Wilson (1989) Scientific Core Hole Valles Caldera No. 2B (VC-2B), New Mexico:...
Supermassive Black Holes at the Center of Galaxies
Christopher J. Greenwood
2005-12-13T23:59:59.000Z
This was my final paper for the AST 308 Galaxies class at Michigan State University. Using many sources I was able to compile a moderate amount of information concerning the evidence for, and the formation of Supermassive Black Holes.
Giant black hole ringings induced by massive gravity
Yves Decanini; Antoine Folacci; Mohamed Ould El Hadj
2014-01-01T23:59:59.000Z
A distorted black hole radiates gravitational waves in order to settle down in one of the geometries permitted by the no-hair theorem. During that relaxation phase, a characteristic damped ringing is generated. It can be theoretically constructed from the black hole quasinormal frequencies (which govern its oscillating behavior and its decay) and from the associated excitation factors (which determine intrinsically its amplitude) by carefully taking into account the source of the distortion. Here, by considering the Schwarzschild black hole in the framework of massive gravity, we show that the excitation factors have an unexpected strong resonant behavior leading to giant ringings which are, moreover, slowly decaying. Such extraordinary black hole ringings could be observed by the next generations of gravitational wave detectors and allow us to test the various massive gravity theories or their absence could be used to impose strong constraints on the graviton mass.
Quantum Emission from Two-Dimensional Black Holes
Steven B. Giddings; W. M. Nelson
2009-11-27T23:59:59.000Z
We investigate Hawking radiation from two-dimensional dilatonic black holes using standard quantization techniques. In the background of a collapsing black hole solution the Bogoliubov coefficients can be exactly determined. In the regime after the black hole has settled down to an `equilibrium' state but before the backreaction becomes important these give the known result of a thermal distribution of Hawking radiation at temperature lambda/(2pi). The density matrix is computed in this regime and shown to be purely thermal. Similar techniques can be used to derive the stress tensor. The resulting expression agrees with the derivation based on the conformal anomaly and can be used to incorporate the backreaction. Corrections to the thermal density matrix are also examined, and it is argued that to leading order in perturbation theory the effect of the backreaction is to modify the Bogoliubov transformation, but not in a way that restores information lost to the black holes.
Neural network calibration for miniature multi-hole pressure probes
Vijayagopal, Rajesh
1998-01-01T23:59:59.000Z
A robust and accurate neural network based algorithm phics. for the calibration of miniature multi-hole pressure probes has been developed and a detailed description of its features and use is presented. The code that was developed was intended...
Numerical investigation of the threshold for primordial black hole formation
J. C. Niemeyer
1998-06-02T23:59:59.000Z
First results of a numerical investigation of primordial black hole formation in the radiation dominated phase of the Early Universe are presented. The simulations follow the gravitational collapse of three different families of high-amplitude density fluctuations imposed at the time of horizon crossing. The threshold for black hole formation, \\delta_{c} \\approx 0.7, is found to be nearly identical for all perturbation families if the control parameter, \\delta, is chosen as the total excess mass within the initial horizon volume. Furthermore, we demonstrate that the scaling of black hole mass with distance from the formation threshold, known to occur in near-critical gravitational collapse, applies to primordial black hole formation.
Rotating Hayward's regular black hole as particle accelerator
Muhammed Amir; Sushant G. Ghosh
2015-06-10T23:59:59.000Z
Recently, Ban\\~{a}dos, Silk and West (BSW) demonstrated that the extremal Kerr black hole can act as a particle accelerator with arbitrarily high center-of-mass energy ($E_{CM}$) when the collision takes place near the horizon. The rotating Hayward's regular black hole, apart from Mass ($M$) and angular momentum ($a$), has a new parameter $g$ ($g>0$ is a constant) that provides a deviation from the Kerr black hole. We demonstrate that for each $g$, with $M=1$, there exist critical $a_{E}$ and $r_{H}^{E}$, which corresponds to a regular extremal black hole with degenerate horizon, and $a_{E}$ decreases and $r_{H}^{E}$ increases with increase in $g$. While $aparticle accelerator and thus in turn may provide a suitable framework for Plank-scale physics. For a non-extremal case, there always exist a finite upper bound of $E_{CM}$, which increases with deviation parameter $g$.
Hole in one: Technicians smoothly install the center stack in...
Broader source: All U.S. Department of Energy (DOE) Office Webpages (Extended Search)
Hole in one: Technicians smoothly install the center stack in the NSTX-U vacuum vessel By John Greenwald November 10, 2014 Tweet Widget Google Plus One Share on Facebook Closeup of...
Temperatures, heat flow, and water chemistry from drill holes...
Temperatures, heat flow, and water chemistry from drill holes in the Raft River geothermal system, Cassia County, Idaho Jump to: navigation, search OpenEI Reference LibraryAdd to...
Strong gravitational lensing in a noncommutative black-hole spacetime
Ding Chikun; Kang Shuai; Chen Changyong; Chen Songbai; Jing Jiliang [Department of Physics and Information Engineering, Hunan Institute of Humanities Science and Technology, Loudi, Hunan 417000 (China); Institute of Physics and Department of Physics, Hunan Normal University, Changsha, Hunan 410081 (China) and Key Laboratory of Low Dimensional Quantum Structures and Quantum Control (Hunan Normal University), Ministry of Education (China)
2011-04-15T23:59:59.000Z
Noncommutative geometry may be a starting point to a quantum gravity. We study the influence of the spacetime noncommutative parameter on the strong field gravitational lensing in the noncommutative Schwarzschild black-hole spacetime and obtain the angular position and magnification of the relativistic images. Supposing that the gravitational field of the supermassive central object of the galaxy can be described by this metric, we estimate the numerical values of the coefficients and observables for strong gravitational lensing. In comparison to the Reissner-Norstroem black hole, we find that the influences of the spacetime noncommutative parameter is similar to those of the charge, but these influences are much smaller. This may offer a way to distinguish a noncommutative black hole from a Reissner-Norstroem black hole, and may permit us to probe the spacetime noncommutative constant {theta} by the astronomical instruments in the future.
Black hole evaporation in a noncommutative charged Vaidya model
Sharif, M., E-mail: msharif.math@pu.edu.pk; Javed, W. [University of the Punjab, Department of Mathematics (Pakistan)
2012-06-15T23:59:59.000Z
We study the black hole evaporation and Hawking radiation for a noncommutative charged Vaidya black hole. For this purpose, we determine a spherically symmetric charged Vaidya model and then formulate a noncommutative Reissner-Nordstroem-like solution of this model, which leads to an exact (t - r)-dependent metric. The behavior of the temporal component of this metric and the corresponding Hawking temperature are investigated. The results are shown in the form of graphs. Further, we examine the tunneling process of charged massive particles through the quantum horizon. We find that the tunneling amplitude is modified due to noncommutativity. Also, it turns out that the black hole evaporates completely in the limits of large time and horizon radius. The effect of charge is to reduce the temperature from a maximum value to zero. We note that the final stage of black hole evaporation is a naked singularity.
Circumnuclear Media and Accretion Rates of Quiescent Supermassive Black Holes
Generozov, Aleksey; Metzger, Brian D
2015-01-01T23:59:59.000Z
We calculate steady-state, one-dimensional hydrodynamic profiles of hot gas in slowly accreting ("quiescent") galactic nuclei for a range of central black hole masses, parameterized gas heating rates, and observationally-motivated stellar density profiles. Mass is supplied to the circumnuclear medium by stellar winds, while energy is injected primarily by stellar winds, supernovae, and black hole feedback. Analytic estimates are derived for the stagnation radius (where the radial velocity of the gas passes through zero) and the black hole accretion rate, as a function of the black hole mass and the gas heating efficiency, the latter being related to the star-formation history. We assess the conditions under which radiative instabilities develop in the hydrostatic region near the stagnation radius, both in the case of a single burst of star formation and for the average star formation history predicted by cosmological simulations. By combining a sample of measured nuclear X-ray luminosities from nearby quiesce...
Could there be a hole in type Ia supernovae?
Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan
2004-01-01T23:59:59.000Z
Highlight: The Physics of Supernovae. Pro- ceedings of the EThere Be A Hole In Type l a Supernovae? Daniel Kasen, Peterscenario, Type l a Supernovae (SNe la) arise from a white
On the black hole limit of rotating discs and rings
Andreas Kleinwächter; Hendrick Labranche; Reinhard Meinel
2010-07-20T23:59:59.000Z
Solutions to Einstein's field equations describing rotating fluid bodies in equilibrium permit parametric (i.e. quasi-stationary) transitions to the extreme Kerr solution (outside the horizon). This has been shown analytically for discs of dust and numerically for ring solutions with various equations of state. From the exterior point of view, this transition can be interpreted as a (quasi) black hole limit. All gravitational multipole moments assume precisely the values of an extremal Kerr black hole in the limit. In the present paper, the way in which the black hole limit is approached is investigated in more detail by means of a parametric Taylor series expansion of the exact solution describing a rigidly rotating disc of dust. Combined with numerical calculations for ring solutions our results indicate an interesting universal behaviour of the multipole moments near the black hole limit.
Lovelock black holes in a string cloud background
Tae-Hun Lee; Dharmanand Baboolal; Sushant G. Ghosh
2015-06-11T23:59:59.000Z
We present an exact static, spherically symmetric black hole solution to the third order Lovelock gravity with a string cloud background in seven dimensions for the special case when the second and third order Lovelock coefficients are related via $\\tilde{\\alpha}^2_2=3\\tilde{\\alpha}_3\\;(\\equiv\\alpha^2)$. Further, we examine thermodynamic properties of this black hole to obtain exact expressions for mass, temperature, entropy and also perform the thermodynamic stability analysis. We see that a string cloud background makes a profound influence on horizon structure, thermodynamic properties and the stability of black holes. Interestingly the entropy of the black hole is unaffected due to a string cloud background. However, the critical solution for thermodynamic stability is being affected by a string cloud background.
Tensile Strength and the Mining of Black Holes
Adam R. Brown
2012-07-13T23:59:59.000Z
There are a number of important thought experiments that involve raising and lowering boxes full of radiation in the vicinity of black hole horizons. This paper looks at the limitations placed on these thought experiments by the null energy condition, which imposes a fundamental bound on the tensile-strength-to-weight ratio of the materials involved, makes it impossible to build a box near the horizon that is wider than a single wavelength of the Hawking quanta and puts a severe constraint on the operation of 'space elevators' near black holes. In particular, it is shown that proposals for mining black holes by lowering boxes near the horizon, collecting some Hawking radiation and dragging it out to infinity cannot proceed nearly as rapidly as has previously been claimed and that as a consequence of this limitation the boxes and all the moving parts are superfluous and black holes can be destroyed equally rapidly by threading the horizon with strings.
Structure of the Inner Singularity of a Spherical Black Hole
A. Bonanno; S. Droz; W. Israel; S. M. Morsink
1994-03-10T23:59:59.000Z
We review the evidence for and against the possibility that the inner singularity of a black hole contains a lightlike segment which is locally mild and characterized by mass inflation.
Thermal Gradient Holes At Lightning Dock Geothermal Area (Arnold...
DOE-funding Unknown Exploration Basis Known shallow hot spot in Animas Valley Notes Four thermal gradient holes were authorized to be drilled by AMEX, but no results were...
Flow localization in sheet specimens with pairs of holes
Geltmacher, A.B. [FM Technologies, Fairfax, VA (United States); Koss, D.A. [Pennsylvania State Univ., University Park, PA (United States). Dept. of Metals Science and Engineering; Stout, M.G. [Los Alamos National Lab., NM (United States); Matic, P. [Naval Research Lab., Washington, DC (United States). Mechanics of Materials Dept.
1998-03-01T23:59:59.000Z
The deformation localization behavior of sheet specimens containing geometric perturbations in the form of pairs of through-thickness holes is examined. Both experiments and computational modeling are performed in either uniaxial or equal-biaxial tension in order to examine the effect of applied loading path on the far-field strain needed to initiate localized necking in the ligament between the hole pairs. The models also examine the influence of hole spacing and matrix strain hardening on ligament localization. The far-field strain needed to cause the localization of the ligament is shown to increase as the biaxiality of the loading path increases, the hole spacing increases, and the strain-hardening exponent increases. The present study also indicates that the onset of localized necking can be predicted by employing the Hill criterion, if the local strain states within the ligament are taken into account.
Vortex hair on AdS black holes
Gregory, Ruth; Kubiznak, David; Mann, Robert B; Wills, Danielle
2014-01-01T23:59:59.000Z
We analyse vortex hair for charged rotating asymptotically AdS black holes in the abelian Higgs model. We give analytical and numerical arguments to show how the vortex interacts with the horizon of the black hole, and how the solution extends to the boundary. The solution is very close to the corresponding asymptotically flat vortex, once one transforms to a frame that is non-rotating at the boundary. We show that there is a Meissner effect for extremal black holes, with the vortex flux being expelled from sufficiently small black holes. The phase transition is shown to be first order in the presence of rotation, but second order without rotation. We comment on applications to holography.
THE RELATION BETWEEN BLACK HOLE MASS AND HOST SPHEROID STELLAR MASS OUT TO z {approx} 2
Bennert, Vardha N.; Auger, Matthew W.; Treu, Tommaso [Department of Physics, University of California, Santa Barbara, CA 93106 (United States); Woo, Jong-Hak [Astronomy Program, Department of Physics and Astronomy, Seoul National University (Korea, Republic of); Malkan, Matthew A., E-mail: vbennert@calpoly.edu, E-mail: tt@physics.ucsb.edu, E-mail: mauger@ast.cam.ac.uk, E-mail: woo@astro.snu.ac.kr, E-mail: malkan@astro.ucla.edu [Department of Physics and Astronomy, University of California, Los Angeles, CA 90095 (United States)
2011-12-01T23:59:59.000Z
We combine Hubble Space Telescope images from the Great Observatories Origins Deep Survey with archival Very Large Telescope and Keck spectra of a sample of 11 X-ray-selected broad-line active galactic nuclei in the redshift range 1 < z < 2 to study the black-hole-mass-stellar-mass relation out to a look-back time of 10 Gyr. Stellar masses of the spheroidal component (M{sub sph,*}) are derived from multi-filter surface photometry. Black hole masses (M{sub BH}) are estimated from the width of the broad Mg II emission line and the 3000 A nuclear luminosity. Comparing with a uniformly measured local sample and taking into account selection effects, we find evolution in the form M{sub BH}/M{sub sph,*}{proportional_to}(1 + z){sup 1.96{+-}}0{sup .55}, in agreement with our earlier studies based on spheroid luminosity. However, this result is more accurate because it does not require a correction for luminosity evolution and therefore avoids the related and dominant systematic uncertainty. We also measure total stellar masses (M{sub host,*}). Combining our sample with data from the literature, we find M{sub BH}/M{sub host,*}{proportional_to}(1 + z){sup 1.15{+-}0.15}, consistent with the hypothesis that black holes (in the range M{sub BH} {approx} 10{sup 8-9} M{sub Sun }) pre-date the formation of their host galaxies. Roughly, one-third of our objects reside in spiral galaxies; none of the host galaxies reveal signs of interaction or major merger activity. Combined with the slower evolution in host stellar masses compared to spheroid stellar masses, our results indicate that secular evolution or minor mergers play a non-negligible role in growing both BHs and spheroids.
Black Hole Radiation On and Off the Brane
Roberto Emparan
2000-09-26T23:59:59.000Z
After a brief review of the description of black holes on branes, we examine the evaporation of a small black hole on a brane in a world with large extra dimensions. We show that, contrary to previous claims, most of the energy is radiated into the modes on the brane. This raises the possibility of observing Hawking radiation in future high energy colliders if there are large extra dimensions.
Hawking Radiation as Tunnelling in Static Black Holes
Wenbiao Liu
2005-12-16T23:59:59.000Z
Hawking radiation can usefully be viewed as a semi-classical tunnelling process that originates at the black hole horizon. The conservation of energy implies the effect of self-gravitation. For a static black hole, a generalized Painleve coordinate system is introduced, and Hawking radiation as tunnelling under the effect of self-gravitation is investigated. The corrected radiation is consistent with the underlying unitary theory.
Hawking Radiation as Tunnelling in Static Black Holes
Liu, W
2005-01-01T23:59:59.000Z
Hawking radiation can usefully be viewed as a semi-classical tunnelling process that originates at the black hole horizon. The conservation of energy implies the effect of self-gravitation. For a static black hole, a generalized Painleve coordinate system is introduced, and Hawking radiation as tunnelling under the effect of self-gravitation is investigated. The corrected radiation is consistent with the underlying unitary theory.
On the Quantum-Corrected Black Hole Thermodynamics
Kourosh Nozari; S. Hamid Mehdipour
2006-01-15T23:59:59.000Z
Bekenstein-Hawking Black hole thermodynamics should be corrected to incorporate quantum gravitational effects. Generalized Uncertainty Principle(GUP) provides a perturbational framework to perform such modifications. In this paper we consider the most general form of GUP to find black holes thermodynamics in microcanonical ensemble. Our calculation shows that there is no logarithmic pre-factor in perturbational expansion of entropy. This feature will solve part of controversies in literatures regarding existence or vanishing of this pre-factor.
Exploring the string axiverse with precision black hole physics
Arvanitaki, Asimina [Berkeley Center for Theoretical Physics, University of California, Berkeley, California, 94720 (United States); Theoretical Physics Group, Lawrence Berkeley National Laboratory, Berkeley, California, 94720 (United States); Dubovsky, Sergei [Department of Physics, Stanford University, Stanford, California, 94305 (United States); Institute for Nuclear Research of the Russian Academy of Sciences, 60th October Anniversary Prospect, 7a, 117312 Moscow (Russian Federation)
2011-02-15T23:59:59.000Z
It has recently been suggested that the presence of a plenitude of light axions, an Axiverse, is evidence for the extra dimensions of string theory. We discuss the observational consequences of these axions on astrophysical black holes through the Penrose superradiance process. When an axion Compton wavelength is comparable to the size of a black hole, the axion binds to the black hole ''nucleus'' forming a gravitational atom in the sky. The occupation number of superradiant atomic levels, fed by the energy and angular momentum of the black hole, grows exponentially. The black hole spins down and an axion Bose-Einstein condensate cloud forms around it. When the attractive axion self-interactions become stronger than the gravitational binding energy, the axion cloud collapses, a phenomenon known in condensed matter physics as 'bosenova'. The existence of axions is first diagnosed by gaps in the mass vs spin plot of astrophysical black holes. For young black holes the allowed values of spin are quantized, giving rise to ''Regge trajectories'' inside the gap region. The axion cloud can also be observed directly either through precision mapping of the near-horizon geometry or through gravitational waves coming from the bosenova explosion, as well as axion transitions and annihilations in the gravitational atom. Our estimates suggest that these signals are detectable in upcoming experiments, such as Advanced LIGO, AGIS, and LISA. Current black hole spin measurements imply an upper bound on the QCD axion decay constant of 2x10{sup 17} GeV, while Advanced LIGO can detect signals from a QCD axion cloud with a decay constant as low as the GUT scale. We finally discuss the possibility of observing the {gamma}-rays associated with the bosenova explosion and, perhaps, the radio waves from axion-to-photon conversion for the QCD axion.
Discovering the QCD Axion with Black Holes and Gravitational Waves
Asimina Arvanitaki; Masha Baryakhtar; Xinlu Huang
2015-03-23T23:59:59.000Z
Advanced LIGO may be the first experiment to detect gravitational waves. Through superradiance of stellar black holes, it may also be the first experiment to discover the QCD axion with decay constant above the GUT scale. When an axion's Compton wavelength is comparable to the size of a black hole, the axion binds to the black hole, forming a "gravitational atom." Through the superradiance process, the number of axions occupying the bound levels grows exponentially, extracting energy and angular momentum from the black hole. Axions transitioning between levels of the gravitational atom and axions annihilating to gravitons can produce observable gravitational wave signals. The signals are long-lasting, monochromatic, and can be distinguished from ordinary astrophysical sources. We estimate up to O(1) transition events at aLIGO for an axion between 10^-11 and 10^-10 eV and up to 10^4 annihilation events for an axion between 10^-13 and 10^-11 eV. In the event of a null search, aLIGO can constrain the axion mass for a range of rapidly spinning black hole formation rates. Axion annihilations are also promising for much lighter masses at future lower-frequency gravitational wave observatories; the rates have large uncertainties, dominated by supermassive black hole spin distributions. Our projections for aLIGO are robust against perturbations from the black hole environment and account for our updated exclusion on the QCD axion of 6*10^-13 eV < ma < 2*10^-11 eV suggested by stellar black hole spin measurements.
On the energy of Ho?ava-Lifshitz black holes
I. Radinschi; F. Rahaman; A. Banerjee
2011-02-10T23:59:59.000Z
In this paper we calculate the energy distribution of the Mu-in Park, Kehagias-Sfetsos (KS) and L\\"u, Mei and Pope (LMP) black holes in the Ho\\v{r}ava-Lifshitz theory of gravity. These black hole solutions correspond to the standard Einstein-Hilbert action in the infrared limit. For our calculations we use the Einstein and M{\\o}ller prescriptions. Various limiting and particular cases are also discussed.
Flux avalanches in superconducting films with periodic arrays of holes.
Vlasko-Vlasov, V.; Welp, U.; Metlushko, V.; Crabtree, G. W.; Materials Science Division; Inst. of Solid State Physics RAS
2000-01-01T23:59:59.000Z
The magnetic flux dynamics in Nb films with periodic hole arrays is studied magneto-optically. Flux motion in the shape of microavalanches along {l_brace}100{r_brace} and {l_brace}110{r_brace} directions of the hole lattice is observed. At lower temperatures anisotropic large scale thermo-magnetic avalanches dominate flux entry and exit. At T-T{sub c} critical-state-like field patterns periodically appear at fractions of the matching field.
Topological aspect of black hole with Skyrme hair
Yi-Shi Duan; Xin-Hui Zhang; Li Zhao
2007-03-19T23:59:59.000Z
Based on the $\\phi$-mapping topological current theory, we show that the presence of the black hole leaves fractional baryon charge outside the horizon in the Einstein-Skyrme theory. A topological current is derived from the Einstein-Skyrme system, which corresponds to the monopoles around the black hole. The branch process (splitting, merging and intersection) is simply discussed during the evolution of the monopoles.
Towards a characterization of fields leading to black hole hair
Narayan Banerjee; Somasri Sen
2013-07-05T23:59:59.000Z
In the present work, it is shown that an asymptotically flat spherical black hole can have a nontrivial signature of any field for an exterior observer if the energy momentum tensor of the corresponding field is either tracefree or if the trace falls off at least as rapidly as inverse cube of the radial distance. In the absence of a general No Hair Theorem, this result can provide a characterization of the fields leading to black hole hair.
Masses of Stellar Black Holes and Testing Theories of Gravitation
K. A. Postnov; A. M. Cherepashchuk
2004-01-22T23:59:59.000Z
We analyze the mass distribution of stellar black holes derived from the light and radial velocity curves of optical stars in close binary systems using dynamical methods. The systematic errors inherent in this approach are discussed. These are associated primarily with uncertainties in models for the contribution from gaseous structures to the optical brightness of the systems under consideration. The mass distribution is nearly flat in the range 4-15M_sun. This is compared with the mass distribution for black holes in massive close binaries, which can be manifest as ultraluminous X-ray sources (L_x > 10^39 erg/s) observed in other galaxies. If the X-ray luminosities of these objects correspond to the Eddington limit, the black-hole mass distribution should be described by a power law, which is incompatible with the flat shape derived dynamically from observations of close binaries in our Galaxy. One possible explanation of this discrepancy is the rapid evaporation of stellar-mass black holes predicted in recent multi-dimensional models of gravity. This hypothesis can be verifed by measuring the stellar black-hole mass spectrum or finding isolated or binary black holes with masses below 3M_sun.
Thermodynamic properties of asymptotically Reissner–Nordström black holes
Hendi, S.H., E-mail: hendi@shirazu.ac.ir
2014-07-15T23:59:59.000Z
Motivated by possible relation between Born–Infeld type nonlinear electrodynamics and an effective low-energy action of open string theory, asymptotically Reissner–Nordström black holes whose electric field is described by a nonlinear electrodynamics (NLED) are studied. We take into account a four dimensional topological static black hole ansatz and solve the field equations, exactly, in terms of the NLED as a matter field. The main goal of this paper is investigation of thermodynamic properties of the obtained black holes. Moreover, we calculate the heat capacity and find that the nonlinearity affects the minimum size of stable black holes. We also use Legendre-invariant metric proposed by Quevedo to obtain scalar curvature divergences. We find that the singularities of the Ricci scalar in Geometrothermodynamics (GTD) method take place at the Davies points. -- Highlights: •We examine the thermodynamical properties of black holes in Einstein gravity with nonlinear electrodynamics. •We investigate thermodynamic stability and discuss about the size of stable black holes. •We obtain analytical solutions of higher dimensional theory.
Could there be a hole in type Ia supernovae?
Kasen, Daniel; Nugent, Peter; Thomas, R.C.; Wang, Lifan
2004-04-23T23:59:59.000Z
In the favored progenitor scenario, Type Ia supernovae (SNe Ia) arise from a white dwarf accreting material from a non-degenerate companion star. Soon after the white dwarf explodes, the ejected supernova material engulfs the companion star; two-dimensional hydrodynamical simulations by Marietta et al. (2001) show that, in the interaction, the companion star carves out a conical hole of opening angle 30-40 degrees in the supernova ejecta. In this paper we use multi-dimensional Monte Carlo radiative transfer calculations to explore the observable consequences of an ejecta-hole asymmetry. We calculate the variation of the spectrum, luminosity, and polarization with viewing angle for the aspherical supernova near maximum light. We find that the supernova looks normal from almost all viewing angles except when one looks almost directly down the hole. In the latter case, one sees into the deeper, hotter layers of ejecta. The supernova is relatively brighter and has a peculiar spectrum characterized by more highly ionized species, weaker absorption features, and lower absorption velocities. The spectrum viewed down the hole is comparable to the class of SN 1991T-like supernovae. We consider how the ejecta-hole asymmetry may explain the current spectropolarimetric observations of SNe Ia, and suggest a few observational signatures of the geometry. Finally, we discuss the variety currently seen in observed SNe Ia and how an ejecta-hole asymmetry may fit in as one of several possible sources of diversity.
The mass function of high redshift seed black holes
Giuseppe Lodato; Priyamvada Natarajan
2007-02-13T23:59:59.000Z
In this paper we derive the mass function of seed black holes that result from the central mass concentrated via disc accretion in collapsed haloes at redshift $z\\approx 15$. Using standard arguments including stability, we show that these pre-galactic discs can assemble a significant mass concentration in the inner regions, providing fuel for the formation and initial growth of super-massive black holes. Assuming that these mass concentrations do result in central seed black holes, we determine the mass distribution of these seeds as a function of key halo properties. The seed mass distribution determined here turns out to be asymmetric and skewed to higher masses. Starting with these initial seeds, building up to $10^9$ solar masses by $z = 6$ to power the bright quasars is not a problem in the standard LCDM cosmogony. These seed black holes in gas rich environments are likely to grow into the supermassive black holes at later times via mergers and accretion. Gas accretion onto these seeds at high redshift will produce miniquasars that likely play an important role in the reionization of the Universe. Some of these seed black holes on the other hand could be wandering in galaxy haloes as a consequence of frequent mergers, powering the off-nuclear ultra-luminous X-ray sources detected in nearby galaxies.
Hawking Radiation of a Charged Black Hole in Quantum Gravity
Ichiro Oda
2015-03-18T23:59:59.000Z
We study black hole radiation of a Reissner-Nordstrom black hole with an electric charge in the framework of quantum gravity. Based on a canonical quantization for a spherically symmetric geometry, under physically plausible assumptions, we solve the Wheeler-De Witt equation in the regions not only between the outer apparent horizon and the spatial infinity but also between the spacetime singularity and the inner apparent horizon, and then show that the mass loss rate of an evaporating black hole due to thermal radiation agrees with the semiclassical result when we choose an integration constant properly by physical reasoning. Furthermore, we also solve the Wheeler-De Witt equation in the region between the inner Cauchy horizon and the outer apparent horizon, and show that the mass loss rate of an evaporating black hole has the same expression. The present study is the natural generalization of the case of a Schwarzschild black hole to that of a charged Reissner-Nordstrom black hole.
Black Hole Remnants and the Information Loss Paradox
Pisin Chen; Yen Chin Ong; Dong-han Yeom
2015-01-30T23:59:59.000Z
Forty years after the discovery of Hawking radiation, its exact nature remains elusive. If Hawking radiation does not carry any information out from the ever shrinking black hole, it seems that unitarity is violated once the black hole completely evaporates. On the other hand, attempts to recover information via quantum entanglement lead to the firewall controversy. Amid the confusions, the possibility that black hole evaporation stops with a "remnant" has remained unpopular and is often dismissed due to some "undesired properties" of such an object. Nevertheless, as in any scientific debate, the pros and cons of any proposal must be carefully scrutinized. We fill in the void of the literature by providing a timely review of various types of black hole remnants, and provide some new thoughts regarding the challenges that black hole remnants face in the context of information loss paradox and its latest incarnation, namely the firewall controversy. The importance of understanding the role of curvature singularity is also emphasized, after all there remains a possibility that singularity cannot be cured even by quantum gravity. In this context a black hole remnant conveniently serves as a cosmic censor. We conclude that a remnant remains a possible end state of Hawking evaporation, and if it contains large interior geometry, may help to ameliorate information loss and the firewall paradox. We hope that this will raise some interests in the community to investigate remnants more critically but also more thoroughly.
Hawking Radiation of a Charged Black Hole in Quantum Gravity
Oda, Ichiro
2015-01-01T23:59:59.000Z
We study black hole radiation of a Reissner-Nordstrom black hole with an electric charge in the framework of quantum gravity. Based on a canonical quantization for a spherically symmetric geometry, under physically plausible assumptions, we solve the Wheeler-De Witt equation in the regions not only between the outer apparent horizon and the spatial infinity but also between the spacetime singularity and the inner apparent horizon, and then show that the mass loss rate of an evaporating black hole due to thermal radiation agrees with the semiclassical result when we choose an integration constant properly by physical reasoning. Furthermore, we also solve the Wheeler-De Witt equation in the region between the inner Cauchy horizon and the outer apparent horizon, and show that the mass loss rate of an evaporating black hole has the same expression. The present study is the natural generalization of the case of a Schwarzschild black hole to that of a charged Reissner-Nordstrom black hole.
Mining Energy from a Black Hole by Strings
V. Frolov; D. Fursaev
2001-05-10T23:59:59.000Z
We discuss how cosmic strings can be used to mine energy from black holes. A string attached to the black hole gives rise to an additional channel for the energy release. It is demonstrated that when a string crosses the event horizon, its transverse degrees of freedom are thermally excited and thermal string perturbations propagate along the string to infinity. The internal metric induced on the 2D worldsheet of the static string crossing the horizon describes a 2D black hole. For this reason thermal radiation of string excitations propagating along the string can be interpreted as Hawking radiation of the 2D black hole. It is shown that the rate of energy emission through the string channel is of the same order of magnitude as the bulk radiation of the black hole. Thus, for N strings attached to the black hole the efficiency of string channels is increased by factor N. We discuss restrictions on N which exist because of the finite thickness of strings, the gravitational backreaction and quantum fluctuations. Our conclusion is that the energy emission rate by strings can be increased as compared to the standard emission in the bulk by the factor 10^3 for GUT strings and up to the factor 10^{31} for electroweak strings.
Black holes in young stellar clusters
Goswami, Sanghamitra; Kiel, Paul; Rasio, Frederic A. [Department of Physics and Astronomy, Northwestern University, Evanston, IL 60208 (United States)
2014-02-01T23:59:59.000Z
We present theoretical models for stellar black hole (BH) properties in young, massive star clusters. Using a Monte Carlo code for stellar dynamics, we model realistic star clusters with N ? 5 × 10{sup 5} stars and significant binary fractions (up to 50%) with self-consistent treatments of stellar dynamics and stellar evolution. We compute the formation rates and characteristic properties of single and binary BHs for various representative ages, cluster parameters, and metallicities. Because of dynamical interactions and supernova (SN) kicks, more single BHs end up retained in clusters compared to BHs in binaries. We also find that the ejection of BHs from a cluster is a strong function of initial density. In low-density clusters (where dynamical effects are negligible), it is mainly SN kicks that eject BHs from the cluster, whereas in high-density clusters (initial central density ? {sub c}(0) ? 10{sup 5} M {sub ?} pc{sup –3} in our models) the BH ejection rate is enhanced significantly by dynamics. Dynamical interactions of binary systems in dense clusters also modify the orbital period and eccentricity distributions while increasing the probability of a BH having a more massive companion.
Falling through the black hole horizon
Brustein, Ram
2015-01-01T23:59:59.000Z
We consider the fate of a small classical object, a "stick", as it falls through the horizon of a large black hole (BH). Classically, the equivalence principle dictates that the stick is affected by small tidal forces, and Hawking's quantum-mechanical model of BH evaporation makes essentially the same prediction. If, on the other hand, the BH horizon is surrounded by a "firewall", the stick will be consumed as it falls through. We have recently extended Hawking's model by taking into account the quantum fluctuations of the geometry and the classical back-reaction of the emitted particles. Here, we calculate the strain exerted on the falling stick for our model. The strain depends on the near-horizon state of the Hawking pairs. We find that, after the Page time when the state of the pairs deviates significantly from maximal entanglement (as required by unitarity), the induced strain in our semiclassical model is still parametrically small. This is because the number of the disentangled pairs is parametrically ...
Black holes, cuspy atmospheres, and galaxy formation
James Binney
2004-07-12T23:59:59.000Z
In cuspy atmospheres, jets driven by supermassive black holes (BHs) offset radiative cooling. The jets fire episodically, but often enough that the cuspy atmosphere does not move very far towards a cooling catastrophe in the intervals of jet inactivity. The ability of energy released on the sub-parsec scale of the BH to balance cooling on scales of several tens of kiloparsecs arises through a combination of the temperature sensitivity of the accretion rate and the way in which the radius of jet disruption varies with ambient density. Accretion of hot gas does not significantly increase BH masses, which are determined by periods of rapid BH growth and star formation when cold gas is briefly abundant at the galactic centre. Hot gas does not accumulate in shallow potential wells. As the Universe ages, deeper wells form, and eventually hot gas accumulates. This gas soon prevents the formation of further stars, since jets powered by the BH prevent it from cooling, and it mops up most cold infalling gas before many stars can form. Thus BHs set the upper limit to the masses of galaxies. The formation of low-mass galaxies is inhibited by a combination of photo-heating and supernova-driven galactic winds. Working in tandem these mechanisms can probably explain the profound difference between the galaxy luminosity function and the mass function of dark halos expected in the cold dark matter cosmology.
A feedback compression star formation model and the black hole - bulge relations
Bing-Xiao Xu; Xue-Bing Wu
2007-06-05T23:59:59.000Z
We present a "feedback compression" model to describe the galactic spheroid formation and its relation with the central nuclear activity. We suggest that the star formation itself can serve as the "positive feedback" in some extremely dense region to trigger the starburst. The star formation rate as well as the related stellar feedback-induced turbulence will be maximized under the regulation of the background dark halo's gravity. There is also stellar feedback acting inward to confine and obscure the central black hole (BH) till the BH grows sufficiently large to satisfy a balance condition between the accretion disk wind and the inward stellar feedback. The extremely vigorous star formation activity, the BH - bulge relations, the maximum velocity dispersion as well as the maximum BH mass are investigated based on such scenario, and are found to be consistent with observations.
Electromagnetic Signatures of Massive Black Hole Binaries
Tamara Bogdanovic; Britton D. Smith; Michael Eracleous; Steinn Sigurdsson
2006-09-28T23:59:59.000Z
We model the electromagnetic emission signatures of massive black hole binaries (MBHBs) with an associated gas component. The method comprises numerical simulations of relativistic binaries and gas coupled with calculations of the physical properties of the emitting gas. We calculate the accretion powered UV/X-ray and Halpha light curves and the Halpha emission line profiles. The simulations have been carried out with a modified version of the parallel tree SPH code Gadget. The heating, cooling, and radiative processes for the solar metallicity gas have been calculated with the photoionization code Cloudy. We investigate gravitationally bound, sub-parsec binaries which have not yet entered the gravitational radiation phase. The results from the first set of calculations, carried out for a coplanar binary and gas disk, suggest that the outbursts in the X-ray light curve are pronounced during pericentric passages and can serve as a fingerprint for this type of binaries if periodic outbursts are a long lived signature of the binary. The Halpha emission-line profiles also offer strong indications of a binary presence and may be used as a criterion for selection of MBHB candidates for further monitoring from existing archival data. The orbital period and mass ratio of a binary could be determined from the Halpha light curves and profiles of carefully monitored candidates. Although systems with the orbital periods studied here are not within the frequency band of the Laser Interferometer Space Antenna (LISA), their discovery is important for understanding of the merger rates of MBHBs and the evolution of such binaries through the last parsec and towards the detectable gravitational wave window.
Accretion onto Supermassive Black Holes in Quasars: Learning from Optical/UV Observations
Paola Marziani; Deborah Dultzin-Hacyan; Jack W. Sulentic
2006-06-28T23:59:59.000Z
Accretion processes in quasars and active galactic nuclei are still poorly understood, especially as far as the connection between observed spectral properties and physical parameters is concerned. Quasars show an additional degree of complexity compared to stars that is related to anisotropic emission/obscuration influencing the observed properties in most spectral ranges. This complicating factor has hampered efforts to define the equivalent of an Hertzsprung-Russel diagram for quasars. Even if it has recently become possible to estimate black hole mass and Eddington ratio for sources using optical and UV broad emission lines, the results are still plagued by large uncertainties. Nevertheless, robust trends are emerging from multivariate analysis of large spectral datasets of quasars. A firm observational basis is being laid out by accurate measurements of broad emission line properties especially when the source rest-frame is known. We consider the most widely discussed correlations (i.e. the so-called "eigenvector 1 parameter space" and the "Baldwin effect") and analyze how they can be explained in terms of accretion properties, broad line region structure, and source evolution. We critically review recent estimates of black hole mass, accretion rate, spin and possible orientation indicators, stressing that any improvement in these parameters will provide a much better understanding of the physics and dynamics of the region producing the optical and UV broad emission lines. More accurate measurements of Eddington ratio and black hole mass may have a significant impact on our ideas about evolution of quasar properties with redshift and luminosity as well as on broader cosmological issues.
Slant hole completion test (1991) sidetrack ``as built`` report
Myal, F.R.
1992-05-01T23:59:59.000Z
During the summer of 1990, a slant hole test well, funded by the US Department of Energy, was drilled to 9,466 ft to evaluate the effectiveness of directional drilling in the tight, naturally fractured gas sands and coals of the Mesaverde Group. The surface location of the SHCT No. 1 is 700 ft south of the DOE Multiwell Experiment (MWX) site in Section 34, T6S, R94W, Garfield County, Colorado, approximately 7.5 miles west of Rifle. Mechanical problems following cementing of a production liner resulted in loss of the completion interval, and operations were suspended. In early 1991, DOE decided to sidetrack the hole to permit production testing of the lost interval. The sidetrack was designed to parallel the original wellbore, but to be drilled 1,000 ft to the east to minimize the chances of encountering formation damage from the original hole. The sidetrack, like the original hole, was to intersect the paludal lenticular sands and coals at 60{degrees} and to penetrate the underlying Cozzette sand horizonally. The sidetrack was spudded May 12, 1991. After re-entering the well in late 1991, early production testing of the Cozzette showed that the 300 ft of in-pay horizontal hole can produce at rate 5 to 10 times higher than vertical wells in the same area. This report contains the geological summary and sidetrack drilling operations summary.
Slant hole completion test (1991) sidetrack as built'' report
Myal, F.R.
1992-05-01T23:59:59.000Z
During the summer of 1990, a slant hole test well, funded by the US Department of Energy, was drilled to 9,466 ft to evaluate the effectiveness of directional drilling in the tight, naturally fractured gas sands and coals of the Mesaverde Group. The surface location of the SHCT No. 1 is 700 ft south of the DOE Multiwell Experiment (MWX) site in Section 34, T6S, R94W, Garfield County, Colorado, approximately 7.5 miles west of Rifle. Mechanical problems following cementing of a production liner resulted in loss of the completion interval, and operations were suspended. In early 1991, DOE decided to sidetrack the hole to permit production testing of the lost interval. The sidetrack was designed to parallel the original wellbore, but to be drilled 1,000 ft to the east to minimize the chances of encountering formation damage from the original hole. The sidetrack, like the original hole, was to intersect the paludal lenticular sands and coals at 60{degrees} and to penetrate the underlying Cozzette sand horizonally. The sidetrack was spudded May 12, 1991. After re-entering the well in late 1991, early production testing of the Cozzette showed that the 300 ft of in-pay horizontal hole can produce at rate 5 to 10 times higher than vertical wells in the same area. This report contains the geological summary and sidetrack drilling operations summary.
Mass and Free Energy of Lovelock Black Holes
David Kastor; Sourya Ray; Jennie Traschen
2011-06-20T23:59:59.000Z
An explicit formula for the ADM mass of an asymptotically AdS black hole in a generic Lovelock gravity theory is presented, identical in form to that in Einstein gravity, but multiplied by a function of the Lovelock coupling constants and the AdS curvature radius. A Gauss' law type formula relates the mass, which is an integral at infinity, to an expression depending instead on the horizon radius. This and other thermodynamic quantities, such as the free energy, are then analyzed in the limits of small and large horizon radius, yielding results that are independent of the detailed choice of Lovelock couplings. In even dimensions, the temperature diverges in both limits, implying the existence of a minimum temperature for black holes. The negative free energy of sufficiently large black holes implies the existence of a Hawking-Page transition. In odd dimensions the temperature still diverges for large black holes, which again have negative free energy. However, the temperature vanishes as the horizon radius tends to zero and sufficiently small black holes have positive specific heat.
Black holes with gravitational hair in higher dimensions
Anabalon, Andres [Departamento de Ciencias Facultad de Artes Liberales, Facultad de Ingenieria y Ciencias, Universidad Adolfo Ibanez, Vina Del Mar (Chile); Max-Planck-Institut fuer Gravitationsphysik, Albert-Einstein-Institut, Am Muehlenberg 1 D-14476 Golm (Germany); Canfora, Fabrizio [Centro de Estudios Cientificos (CECS), Casilla 1469 Valdivia (Chile); Giacomini, Alex; Oliva, Julio [Instituto de Ciencias Fisicas y Matematicas, Facultad de Ciencias, Universidad Austral de Chile, Valdivia (Chile)
2011-10-15T23:59:59.000Z
A new class of vacuum black holes for the most general gravity theory leading to second order field equations in the metric in even dimensions is presented. These space-times are locally anti-de Sitter in the asymptotic region, and are characterized by a continuous parameter that does not enter in the conserve charges, nor it can be reabsorbed by a coordinate transformation: it is therefore a purely gravitational hair. The black holes are constructed as a warped product of a two-dimensional space-time, which resembles the r-t plane of the Banados-Teitelboim-Zanelli black hole, times a warp factor multiplying the metric of a D-2-dimensional Euclidean base manifold, which is restricted by a scalar equation. It is shown that all the Noether charges vanish. Furthermore, this is consistent with the Euclidean action approach: even though the black hole has a finite temperature, both the entropy and the mass vanish. Interesting examples of base manifolds are given in eight dimensions which are products of Thurston geometries, giving then a nontrivial topology to the black hole horizon. The possibility of introducing a torsional hair for these solutions is also discussed.
The Rotating Dyonic Black Holes Of Kaluza-Klein Theory
Dean Rasheed
1995-05-06T23:59:59.000Z
The most general electrically and magnetically charged rotating black hole solutions of 5 dimensional \\KK\\ theory are given in an explicit form. Various classical quantities associated with the black holes are derived. In particular, one finds the very surprising result that the gyromagnetic and gyroelectric ratios can become {\\tenit arbitrarily large}. The thermodynamic quantities of the black holes are calculated and a Smarr-type formula is obtained leading to a generalized first law of black hole thermodynamics. The properties of the extreme solutions are investigated and it is shown how they naturally separate into two classes. The extreme solutions in one class are found to have two unusual properties: (i). Their event horizons have zero angular velocity and yet they have non-zero ADM angular momentum. (ii). In certain circumstances it is possible to add angular momentum to these extreme solutions without changing the mass or charges and yet still maintain an extreme solution. Regarding the extreme black holes as elementary particles, their stability is discussed and it is found that they are stable provided they have sufficient angular momentum.
Nearly extremal apparent horizons in simulations of merging black holes
Geoffrey Lovelace; Mark A. Scheel; Robert Owen; Matthew Giesler; Reza Katebi; Bela Szilagyi; Tony Chu; Nicholas Demos; Daniel A. Hemberger; Lawrence E. Kidder; Harald P. Pfeiffer; Nousha Afshari
2015-02-27T23:59:59.000Z
The spin angular momentum $S$ of an isolated Kerr black hole is bounded by the surface area $A$ of its apparent horizon: $8\\pi S \\le A$, with equality for extremal black holes. In this paper, we explore the extremality of individual and common apparent horizons for merging, rapidly spinning binary black holes. We consider simulations of merging black holes with equal masses $M$ and initial spin angular momenta aligned with the orbital angular momentum, including new simulations with spin magnitudes up to $S/M^2 = 0.994$. We measure the area and (using approximate Killing vectors) the spin on the individual and common apparent horizons, finding that the inequality $8\\pi S A$ and for which our lower bound on their Booth-Fairhurst extremality exceeds unity. These superextremal surfaces are always surrounded by marginally outer trapped surfaces (i.e., by apparent horizons) with $8\\pi Shole. (Abstract abbreviated.)
Acceleration of particles by black holes: kinematic explanation
O. B. Zaslavskii
2011-06-21T23:59:59.000Z
A new simple and general explanation of the effect of acceleration of particles by black holes to infinite energies in the centre of mass frame is suggested. It is based on kinematics of particles moving near the horizon. This effect arises when particles of two kinds collide near the horizon. For massive particles, the first kind represents a particle with the generic energy and angular momentum (I call them "usual"). Near the horizon, such a particle has a velocity almost equal to that of light in the frame that corotates with a black hole (the frame is static if a black hole is static). The second kind (called "critical") consists of particles with the velocity vvelocity approaches the speed of light c, the Lorentz factor grows unbound. This explanation applies both to generic rotating black holes and charged ones (even for radial motion of particles). If one of colliding particles is massless (photon), the critical particle is distinguished by the fact that its frequency is finite near the horizon. The existence (or absence) of the effect is determined depending on competition of two factors - gravitational blue shift for a photon propagating towards a black hole and the Doppler effect due to transformation from the locally nonrotating frame to a comoving one. Classification of all possible types of collisions is suggested depending on whether massive or massless particle is critical or usual.
Higher harmonics increase LISA's mass reach for supermassive black holes
K. G. Arun; Bala R. Iyer; B. S. Sathyaprakash; Siddhartha Sinha
2007-06-05T23:59:59.000Z
Current expectations on the signal to noise ratios and masses of supermassive black holes which the Laser Interferometer Space Antenna (LISA) can observe are based on using in matched filtering only the dominant harmonic of the inspiral waveform at twice the orbital frequency. Other harmonics will affect the signal-to-noise ratio of systems currently believed to be observable by LISA. More significantly, inclusion of other harmonics in our matched filters would mean that more massive systems that were previously thought to be {\\it not} visible in LISA should be detectable with reasonable SNRs. Our estimates show that we should be able to significantly increase the mass reach of LISA and observe the more commonly occurring supermassive black holes of masses $\\sim 10^8M_\\odot.$ More specifically, with the inclusion of all known harmonics LISA will be able to observe even supermassive black hole coalescences with total mass $\\sim 10^8 M_\\odot (10^9M_\\odot)$ (and mass-ratio 0.1) for a low frequency cut-off of $10^{-4}{\\rm Hz}$ $(10^{-5}{\\rm Hz})$ with an SNR up to $\\sim 60$ $(\\sim 30)$ at a distance of 3 Gpc. This is important from the astrophysical viewpoint since observational evidence for the existence of black holes in this mass range is quite strong and binaries containing such supermassive black holes will be inaccessible to LISA if one uses as detection templates only the dominant harmonic.
LIFETIME AND RADIATIVE EFFICIENCY VS DENSITY IN THE STRAIN-CONFINED ELECTRON-HOLE LIQUID IN Ge
Kelso, Susan M.
2011-01-01T23:59:59.000Z
electron-hole liquid (SCEHL) in Ge. Sample CR50 was T = 1.9CONFINED ELECTRON-HOLE LIQUID IN Ge Susan M. Kelso and JohnCONFINED ELECTRON-HOLE LIQUID IN Ge Susan M. Kelso and John
Microhole Coiled Tubing Bottom Hole Assemblies
Don Macune
2008-06-30T23:59:59.000Z
The original objective of the project, to deliver an integrated 3 1/8-inch diameter Measurement While Drilling (MWD) and Logging While Drilling (LWD) system for drilling small boreholes using coiled tubing drilling, has been achieved. Two prototype systems have been assembled and tested in the lab. One of the systems has been successfully tested downhole in a conventional rotary drilling environment. Development of the 3 1/8-inch system has also lead to development and commercialization of a slightly larger 3.5-inch diameter system. We are presently filling customer orders for the 3.5-inch system while continuing with commercialization of the 3 1/8-inch system. The equipment developed by this project will be offered for sale to multiple service providers around the world, enabling the more rapid expansion of both coiled tubing drilling and conventional small diameter drilling. The project was based on the reuse of existing technology whenever possible in order to minimize development costs, time, and risks. The project was begun initially by Ultima Labs, at the time a small company ({approx}12 employees) which had successfully developed a number of products for larger oil well service companies. In September, 2006, approximately 20 months after inception of the project, Ultima Labs was acquired by Sondex plc, a worldwide manufacturer of downhole instrumentation for cased hole and drilling applications. The acquisition provided access to proven technology for mud pulse telemetry, downhole directional and natural gamma ray measurements, and surface data acquisition and processing, as well as a global sales and support network. The acquisition accelerated commercialization through existing Sondex customers. Customer demand resulted in changes to the product specification to support hotter (150 C) and deeper drilling (20,000 psi pressure) than originally proposed. The Sondex acquisition resulted in some project delays as the resistivity collar was interfaced to a different MWD system and also as the mechanical design was revised for the new pressure requirements. However, the Sondex acquisition has resulted in a more robust system, secure funding for completion of the project, and more rapid commercialization.
Thermodynamic geometry of charged rotating BTZ black holes
Akbar, M. [Center for Advanced Mathematics and Physics, National University of Sciences and Technology, H-12, Islamabad (Pakistan); Quevedo, H. [Instituto de Ciencias Nucleares, Universidad Nacional Autonoma de Mexico, AP 70543, Mexico, DF 04510 (Mexico); ICRANet, Dipartimento di Fisica, Universita di Roma La Sapienza, I-00185 Roma (Italy); Saifullah, K. [Department of Mathematics, Quaid-i-Azam University, Islamabad (Pakistan); Sanchez, A. [Departamento de Posgrado, CIIDET, AP 752, Queretaro, QRO 76000 (Mexico); Taj, S. [Center for Advanced Mathematics and Physics, National University of Sciences and Technology, H-12, Islamabad (Pakistan); ICRANet, Dipartimento di Fisica, Universita di Roma La Sapienza, I-00185 Roma (Italy)
2011-04-15T23:59:59.000Z
We study the thermodynamics and the thermodynamic geometries of charged rotating Banados-Teitelboim-Zanelli black holes in (2+1)-gravity. We investigate the thermodynamics of these systems within the context of the Weinhold and Ruppeiner thermodynamic geometries and the recently developed formalism of geometrothermodynamics. Considering the behavior of the heat capacity and the Hawking temperature, we show that Weinhold and Ruppeiner geometries cannot describe completely the thermodynamics of these black holes and of their limiting case of vanishing electric charge. In contrast, the Legendre invariance imposed on the metric in geometrothermodynamics allows one to describe the charged rotating Banados-Teitelboim-Zanelli black holes and their limiting cases in a consistent and invariant manner.
Black hole feedback in the luminous quasar PDS 456
Nardini, E; Gofford, J; Harrison, F A; Risaliti, G; Braito, V; Costa, M T; Matzeu, G A; Walton, D J; Behar, E; Boggs, S E; Christensen, F E; Craig, W W; Hailey, C J; Matt, G; Miller, J M; O'Brien, P T; Stern, D; Turner, T J; Ward, M J
2015-01-01T23:59:59.000Z
The evolution of galaxies is connected to the growth of supermassive black holes in their centers. During the quasar phase, a huge luminosity is released as matter falls onto the black hole, and radiation-driven winds can transfer most of this energy back to the host galaxy. Over five different epochs, we detected the signatures of a nearly spherical stream of highly ionized gas in the broadband X-ray spectra of the luminous quasar PDS 456. This persistent wind is expelled at relativistic speeds from the inner accretion disk, and its wide aperture suggests an effective coupling with the ambient gas. The outflow's kinetic power larger than 10^46 ergs per second is enough to provide the feedback required by models of black hole and host galaxy co-evolution.
Supercurrent: Vector Hair for an AdS Black Hole
Pallab Basu; Anindya Mukherjee; Hsien-Hang Shieh
2008-09-26T23:59:59.000Z
In arXiv:0803.3295 [hep-th] a holographic black hole solution is discussed which exhibits a superconductor like transition. In the superconducting phase the black holes show infinite DC conductivity. This gives rise to the possibility of deforming the solutions by turning on a time independent current (supercurrent), without any electric field. This type of deformation does not exist for normal (non-superconducting) black holes, due to the no-hair theorems. In this paper we have studied such a supercurrent solution and the associated phase diagram. Interestingly, we have found a "special point" (critical point) in the phase diagram where the second order superconducting phase transition becomes first order. Supercurrent in superconducting materials is a well studied phenomenon in condensed matter systems. We have found some qualitative agreement with known results.
Holographic Superconductors with Ho?ava-Lifshitz Black Holes
Rong-Gen Cai; Hai-Qing Zhang
2009-12-03T23:59:59.000Z
We discuss the phase transition of planar black holes in Ho\\v{r}ava-Lifshitz gravity by introducing a Maxwell field and a complex scalar field. We calculate the condensates of the charged operators in the dual CFTs when the mass square of the complex scalar filed is $m^2=-2/L^2$ and $m^2=0$, respectively. We compute the electrical conductivity of the \\hl superconductor in the probe approximation. In particular, it is found that there exists a spike in the conductivity for the case of the operator with scaling dimension one. These results are quite similar to those in the case of Schwarzschild-AdS black holes, which demonstrates that the holographic superconductivity is a robust phenomenon associated with asymptotic AdS black holes.
Binary Black Holes in Quasi-Stationary Circular Orbits
Brian D. Baker
2002-05-18T23:59:59.000Z
We propose a method of determining solutions to the constraint equations of General Relativity approximately describing binary black holes in quasi-stationary circular orbits. Black holes with arbitrary linear momenta are constructed in the manner suggested by Brandt and Brugmann. The quasi-stationary circular orbits are determined by local minima in the ADM mass in a manner similar to Baumgarte and Cook; however, rather than fixing the area of the apparent horizon, we fix the value of the bare masses of the holes. We numerically generate an evolutionary sequence of quasi-stationary circular orbits up to and including the innermost stable circular orbit. We compare our results with post-Newtonian expectations as well as the results of Cook and Baumgarte. We also generate additional numerical results describing the dynamics of the geometry due to the emission of gravitational radiation.
Magnetic and Electric Black Holes in Arbitrary Dimension
Adil Belhaj; Pablo Diaz; Antonio segui
2009-06-02T23:59:59.000Z
In this work, we compare two different objects: electric black holes and magnetic black holes in arbitrary dimension. The comparison is made in terms of the corresponding moduli space and their extremal geometries. We treat parallelly the magnetic and the electric cases. Specifically, we discuss the gravitational solution of these spherically symmetric objects in the presence of a positive cosmological constant. Then, we find the bounded region of the moduli space allowing the existence of black holes. After identifying it in both the electric and the magnetic case, we calculate the geometry that comes out between the horizons at the coalescence points. Although the electric and magnetic cases are both very different (only dual in four dimensions), gravity solutions seem to clear up most of the differences and lead to very similar geometries.
BTZ-like black holes in even dimensional Lovelock theories
Canfora, Fabrizio [Centro de Estudios Cientificos (CECS), Casilla 1469 Valdivia (Chile); Giacomini, Alex [Instituto de Fisica, Facultad de Ciencias, Universidad Austral de Chile, Valdivia (Chile)
2010-07-15T23:59:59.000Z
In the present paper, a new class of black hole solutions is constructed in even dimensional Lovelock Born-Infeld theory. These solutions are interesting since, in some respects, they are closer to black hole solutions of an odd dimensional Lovelock Chern-Simons theory than to the more usual black hole solutions in even dimensions. This hybrid behavior arises when non-Einstein base manifolds are considered. The entropies of these solutions have been analyzed using Wald formalism. These metrics exhibit a quite nontrivial behavior. Their entropies can change sign and can even be identically zero depending on the geometry of the corresponding base manifolds. Therefore, the request of thermodynamical stability constrains the geometry of the non-Einstein base manifolds. It will be shown that some of these solutions can support nonvanishing torsion. Eventually, the possibility to define a sort of topological charge associated with torsion will be discussed.
Thermodynamics of topological nonlinear charged Lifshitz black holes
Zangeneh, M Kord; Dehghani, M H
2015-01-01T23:59:59.000Z
In this paper, we construct a new class of analytic topological Lifshitz black holes with constant curvature horizon in the presence of power-law Maxwell field in four and higher dimensions. We find that in order to obtain these exact Lifshitz solutions, we need a dilaton and at least three electromagnetic fields. Interestingly enough, we find that the reality of the charge of the electromagnetic field which is needed for having solutions with curved horizon rules out black holes with hyperbolic horizon. Next, we study the thermodynamics of these nonlinear charged Lifshitz black holes with spherical and flat horizons by calculating all the conserved and thermodynamic quantities of the solutions. Furthermore, we obtain a generalized Smarr formula and show that the first law of thermodynamics is satisfied. Finally, we perform a stability analysis in both canonical and grand-canonical ensembles. We find that the solutions are thermally stable in a proper ranges of the metric parameters.
Thermodynamics of de Sitter Black Holes: Thermal Cosmological Constant
Yuichi Sekiwa
2006-04-10T23:59:59.000Z
We study the thermodynamic properties associated with the black hole event horizon and the cosmological horizon for black hole solutions in asymptotically de Sitter spacetimes. We examine thermodynamics of these horizons on the basis of the conserved charges according to Teitelboim's method. In particular, we have succeeded in deriving the generalized Smarr formula among thermodynamical quantities in a simple and natural way. We then show that cosmological constant must decrease when one takes into account the quantum effect. These observations have been obtained if and only if cosmological constant plays the role of a thermodynamical state variable. We also touch upon the relation between inflation of our universe and a phase transition of black holes.
Hoffmann-Infeld Black Hole Solutions in Lovelock Gravity
Matias Aiello; Rafael Ferraro; Gaston Giribet
2005-05-19T23:59:59.000Z
Five-dimensional black holes are studied in Lovelock gravity coupled to Hoffmann-Infeld non-linear electrodynamics. It is shown that some of these solutions present a double peak behavior of the temperature as a function of the horizon radius. This feature implies that the evaporation process, though drastic for a period, leads to an eternal black hole remnant. Moreover, the form of the caloric curve corresponds to the existence of a plateau in the evaporation rate, which implies that black holes of intermediate scales turn out to be unstable. The geometrical aspects, such as the absence of conical singularity, the structure of horizons, etc. are also discussed. In particular, solutions that are asymptotically AdS arise for special choices of the parameters, corresponding to charged solutions of five-dimensional Chern-Simons gravity.
Cloud of strings for radiating black holes in Lovelock gravity
Sushant G. Ghosh; Sunil D. Maharaj
2014-09-28T23:59:59.000Z
We present exact spherically symmetric null dust solutions in the third order Lovelock gravity with a string cloud background in arbitrary $N$ dimensions,. This represents radiating black holes and generalizes the well known Vaidya solution to Lovelock gravity with a string cloud in the background. We also discuss the energy conditions and horizon structures, and explicitly bring out the effect of the string clouds on the horizon structure of black hole solutions for the higher dimensional general relativity and Einstein-Gauss-Bonnet theories. It turns out that the presence of the coupling constant of the Gauss-Bonnet terms and/or background string clouds completely changes the structure of the horizon and this may lead to a naked singularity. We recover known spherically symmetric radiating models as well as static black holes in the appropriate limits.
Holographic fermions in charged Gauss-Bonnet black hole
Jian-Pin Wu
2011-08-01T23:59:59.000Z
We study the properties of the Green's functions of the fermions in charged Gauss-Bonnet black hole. What we want to do is to investigate how the presence of Gauss-Bonnet coupling constant $\\alpha$ affects the dispersion relation, which is a characteristic of Fermi or non-Fermi liquid, as well as what properties such a system has, for instance, the Particle-hole (a)symmetry. One important result of this research is that we find for $q=1$, the behavior of this system is different from that of the Landau Fermi liquid and so the system can be candidates for holographic dual of generalized non-Fermi liquids. More importantly, the behavior of this system increasingly similar to that of the Landau Fermi liquid when $\\alpha$ is approaching its lower bound. Also we find that this system possesses the Particle-hole asymmetry when $q\
Black holes as particle accelerators: a brief review
Tomohiro Harada; Masashi Kimura
2014-11-18T23:59:59.000Z
Rapidly rotating Kerr black holes can accelerate particles to arbitrarily high energy if the angular momentum of the particle is fine-tuned to some critical value. This phenomenon is robust as it is founded on the basic properties of geodesic orbits around a near-extremal Kerr black hole. On the other hand, the maximum energy of the acceleration is subjected to several physical effects. There is convincing evidence that the particle acceleration to arbitrarily high energy is one of the universal properties of general near-extremal black holes. We also discuss gravitational particle acceleration in more general context. This article is intended to provide a pedagogical introduction to and a brief overview of this topic for non-specialists.
"Kerrr" black hole: the Lord of the String
Smailagic, Anais
2010-01-01T23:59:59.000Z
Kerrr in the title is not a typo. The third "r" stands for "regular", in the sense of pathology-free, rotating black hole. We exhibit a long search-for, exact, Kerr-like, solution of the Einstein equations with novel features: i) no curvature ring singularity; ii) no "anti-gravity" universe with causality violating timelike closed world-lines; iii) no "super-luminal" matter disk. The ring singularity is replaced by a classical, circular, rotating string with Planck tension representing the inner engine driving the rotation of all the surrounding matter. The resulting geometry is regular and smoothly interpolates among inner Minkowski space, borderline deSitter and outer Kerr universe. The key ingredient to cure all unphysical features of the ordinary Kerr black hole is the choice of a "noncommutative geometry inspired" matter source as the input for the Einstein equations, in analogy with spherically symmetric black holes described in earlier works.
Holographic superconductors with Horava-Lifshitz black holes
Cai Ronggen; Zhang Haiqing [Key Laboratory of Frontiers in Theoretical Physics, Institute of Theoretical Physics, Chinese Academy of Sciences, P.O. Box 2735, Beijing 100190 (China)
2010-03-15T23:59:59.000Z
We discuss the phase transition of planar black holes in Horava-Lifshitz gravity by introducing a Maxwell field and a complex scalar field. We calculate the condensate of the charged operators in the dual conformal field theories when the mass square of the complex scalar field is m{sup 2}=-2/L{sup 2} and m{sup 2}=0, respectively. We compute the electrical conductivity of the Horava-Lifshitz superconductor in the probe approximation. In particular, it is found that there exists a spike in the conductivity for the case of the operator with scaling dimension one. These results are quite similar to those in the case of Schwarzschild-AdS black holes, which demonstrates that the holographic superconductivity is a robust phenomenon associated with asymptotic AdS black holes.
Simulations of binary black hole mergers using spectral methods
Szilagyi, Bela; Lindblom, Lee; Scheel, Mark A. [Theoretical Astrophysics 350-17, California Institute of Technology, Pasadena, California 91125 (United States)
2009-12-15T23:59:59.000Z
Several improvements in numerical methods and gauge choice are presented that make it possible now to perform simulations of the merger and ringdown phases of 'generic' binary black hole evolutions using the pseudospectral evolution code SpEC. These improvements include the use of a new damped-wave gauge condition, a new grid structure with appropriate filtering that improves stability, and better adaptivity in conforming the grid structures to the shapes and sizes of the black holes. Simulations illustrating the success of these new methods are presented for a variety of binary black hole systems. These include fairly generic systems with unequal masses (up to 2 ratio 1 mass ratios), and spins (with magnitudes up to 0.4M{sup 2}) pointing in various directions.
Noncommutative effects in the black hole evaporation in two dimensions
Garcia-Compean, Hugo [Centro de Investigacion y de Estudios Avanzados del IPN, Unidad Monterrey Cerro de las Mitras 2565, Colonia Obispado, Monterrey Nuevo Leon 64060 (Mexico); Departamento de Fisica Centro de Investigacion y de Estudios Avanzados del IPN P.O. Box 14-740, 07000 Mexico Distrito Federal (Mexico); Soto-Campos, Carlos [Departamento de Fisica Centro de Investigacion y de Estudios Avanzados del IPN P.O. Box 14-740, 07000 Mexico Distrito Federal (Mexico); Unidad Profesional Interdisciplinaria en Ingenieria y Tecnologias Avanzadas del IPN Avenida IPN 2580 Colonia Laguna Ticoman 07340 Mexico Distrito Federal (Mexico)
2006-11-15T23:59:59.000Z
We discuss some possible implications of a two-dimensional toy model for black hole evaporation in noncommutative field theory. While the noncommutativity we consider does not affect gravity, it can play an important role in the dynamics of massless and Hermitian scalar fields in the event horizon of a Schwarzschild black hole. We find that noncommutativity will affect the flux of outgoing particles and the nature of its UV/IR divergences. Moreover, we show that the noncommutative interaction does not affect Leahy's and Unruh's interpretation of thermal ingoing and outgoing fluxes in the black hole evaporation process. Thus, the noncommutative interaction still destroys the thermal nature of fluxes. In the process, some nonlocal implications of the noncommutativity are discussed.
On Black Hole Masses and Radio Loudness in AGN
Ari Laor
2000-09-13T23:59:59.000Z
The distribution of radio to optical fluxes in AGN is bimodal. The physical origin for this bimodality is not understood. In this Letter I describe observational evidence, based on the Boroson & Green PG quasar sample, that the radio loudness bimodality is strongly related to the black hole mass (M_BH). Nearly all PG quasars with M_BH>10^9M_sun are radio loud, while quasars with M_BH<3x10^8M_sun are practically all radio quiet. This result is consistent with the dependence of quasar host galaxy morphology on radio loudness. There is no simple physical explanation for this result, but it may provide a clue on how jets are formed near massive black holes. The radio loudness--black hole mass relationship suggests that the properties of various types of AGN may be largely set by three basic parameters, M_BH, L/L_Eddington, and inclination angle.
The Mixed Phase of Charged AdS Black holes
Piyabut Burikham; Chatchai Promsiri
2015-01-20T23:59:59.000Z
We study the mixed phase of charged AdS black hole and radiation when the total energy is fixed below the threshold to produce a stable charged black hole branch. The coexistence conditions for the charged AdS black hole and radiation are derived for the generic case when radiation particles carry charge. The phase diagram of the mixed phase is demonstrated for both fixed potential and charge ensemble. In the dual gauge picture, they correspond to the mixed phase of quark-gluon plasma~(QGP) and hadron gas in the fixed chemical potential and density ensemble respectively. In the nuclei and heavy ion collisions at intermediate energies, the mixed phase of exotic QGP and hadron gas could be produced. The mixed phase will condensate and evaporate into the hadron gas as the fireball expands.
Quantum hair and the string-black hole correspondence
Gabriele Veneziano
2013-03-28T23:59:59.000Z
We consider a thought experiment in which an energetic massless string probes a "stringhole" (a heavy string lying on the correspondence curve between strings and black holes) at large enough impact parameter for the regime to be under theoretical control. The corresponding, explicitly unitary, $S$-matrix turns out to be perturbatively sensitive to the microstate of the stringhole: in particular, at leading order in $l_s/b$, it depends on a projection of the stringhole's Lorentz-contracted quadrupole moment. The string-black hole correspondence is therefore violated if one assumes quantum hair to be exponentially suppressed as a function of black-hole entropy. Implications for the information paradox are briefly discussed.
Thermodynamics of Black Hole Horizons and Kerr/CFT Correspondence
Bin Chen; Shen-xiu Liu; Jia-ju Zhang
2012-11-02T23:59:59.000Z
In this paper we investigate the thermodynamics of the inner horizon and its implication on the holographic description of the black hole. We focus on the black holes with two physical horizons. Under reasonable assumption, we prove that the first law of thermodynamics of the outer horizon always indicates that of the inner horizon. As a result, the fact that the area product being mass-independent is equivalent to the relation $T_+S_+=T_-S_-$, with $T_\\pm$ and $S_\\pm$ being the Hawking temperatures and the entropies of the outer and inner horizon respectively. We find that the mass-independence of area product breaks down in general Myers-Perry black holes with spacetime dimension $d\\geq6$ and Kerr-AdS black holes with $d\\geq4$. Moreover we discuss the implication of the first laws of the outer and inner horizons on the thermodynamics of the right- and left-moving sectors of dual CFT in Kerr/CFT correspondence. We show that once the relation $T_+S_+=T_-S_-$ is satisfied, the central charges of two sectors must be same. Furthermore from the thermodynamics relations, we read the dimensionless temperatures of microscopic CFT, which are in exact agreement with the ones obtained from hidden conformal symmetry in the low frequency scattering off the black holes, and then determine the central charges. This method works well in well-known cases in Kerr/CFT correspondence, and reproduce successfully the holographic pictures for 4D Kerr-Newman and 5D Kerr black holes. We go on to predict the central charges and temperatures of a possible holographic CFT description dual to 5D doubly rotating black ring.
Charged black holes in expanding Einstein-de Sitter universes
Manuela G. Rodrigues; Vilson T. Zanchin
2015-02-02T23:59:59.000Z
Inspired in a previous work by McClure and Dyer (Classical Quantum Gravity 23, 1971 (2006)), we analyze some solutions of the Einstein-Maxwell equations which were originally written to describe charged black holes in cosmological backgrounds. A detailed analysis of the electromagnetic sources for a sufficiently general metric is performed, and then we focus on deriving the electromagnetic four-current as well as the conserved electric charge of each metric. The charged McVittie solution is revisited and a brief study of its causal structure is performed, showing that it may represent a charged black hole in an expanding universe, with the black hole horizon being formed at infinite late times. Charged versions of solutions originally put forward by Vaidya (Vd) and Sultana and Dyer (SD) are also analyzed. It is shown that the charged Sultana-Dyer metric requires a global electric current, besides a central (pointlike) electric charge. With the aim of comparing to the charged McVittie metric, new charged solutions of Vd and SD type are considered. In these cases, the original mass and charge parameters are replaced by particular functions of the cosmological time. In the new generalized charged Vaidya metric the black hole horizon never forms, whereas in the new generalized Sultana-Dyer case both the Cauchy and the black hole horizons develop at infinite late times. A charged version of the Thakurta metric is also studied here. It is also a new solution. As in the charged Sultana-Dyer case, the natural source of the electromagnetic field is a central electric charge with an additional global electric current. The global structure is briefly studied and it is verified that the corresponding spacetime may represent a charged black hole in a cosmological background. All the solutions present initial singularities as found in the McVittie metric.
The lifetime problem of evaporating black holes: mutiny or resignation
Carlos Barceló; Raúl Carballo-Rubio; Luis J. Garay; Gil Jannes
2015-02-09T23:59:59.000Z
It is logically possible that regularly evaporating black holes exist in nature. In fact, the prevalent theoretical view is that these are indeed the real objects behind the curtain in astrophysical scenarios. There are several proposals for regularizing the classical singularity of black holes so that their formation and evaporation do not lead to information-loss problems. One characteristic is shared by most of these proposals: these regularly evaporating black holes present long-lived trapping horizons, with absolutely enormous evaporation lifetimes in whatever measure. Guided by the discomfort with these enormous and thus inaccessible lifetimes, we elaborate here on an alternative regularization of the classical singularity, previously proposed by the authors in an emergent gravity framework, which leads to a completely different scenario. In our scheme the collapse of a stellar object would result in a genuine time-symmetric bounce, which in geometrical terms amounts to the connection of a black-hole geometry with a white-hole geometry in a regular manner. The two most differential characteristics of this proposal are: i) the complete bouncing geometry is a solution of standard classical general relativity everywhere except in a transient region that necessarily extends beyond the gravitational radius associated with the total mass of the collapsing object; and ii) the duration of the bounce as seen by external observers is very brief (fractions of milliseconds for neutron-star-like collapses). This scenario motivates the search for new forms of stellar equilibrium different from black holes. In a brief epilogue we compare our proposal with a similar geometrical setting recently proposed by Haggard and Rovelli.
The Solar Wind, CMEs and the Origins of Heliospheric Activity
release o Coronal holes o Source of high-speed solar wind #12;peter.gallagher@tcd.ie #12;#12;peter Parker => Parker Spiral: r - r0 = -(v/ )( - 0) o Winding angle: o Inclined at ~45º at 1 AU and ~90º by 10The Solar Wind, CMEs and the Origins of Heliospheric Activity Peter T. Gallagher School of Physics
Adam R. H. Stevens
2015-02-26T23:59:59.000Z
A key component of explaining the array of galaxies observed in the Universe is the feedback of active galactic nuclei, each powered by a massive black hole's accretion disc. For accretion to occur, angular momentum must be lost by that which is accreted. Electromagnetic radiation must offer some respite in this regard, the contribution for which is quantified in this paper using solely general relativity under the thin-disc regime. Herein, I calculate extremised situations where photons are entirely responsible for energy removal in the disc and then extend and relate this to the standard relativistic accretion disc outlined by Novikov & Thorne that includes the effect of viscosity. While there is potential for the contribution of angular-momentum removal from photons to be >~1% out to ~10^4 Schwarzschild radii, especially if the disc is irradiated and is liberated of angular momentum through scattering, it is more likely of order 10^2 Schwarzschild radii if thermal emission from the disc itself is stronger. Near the horizons of fast-spinning black holes, these modes of angular-momentum liberation become dominant.
Construction of a Penrose Diagram for an Accreting Black Hole
Beth A. Brown; James Lindesay
2008-11-04T23:59:59.000Z
A Penrose diagram is constructed for a spatially coherent black hole that accretes at stepwise steady rates as measured by a distant observer from an initial state described by a metric of Minkowski form. Coordinate lines are computationally derived, and radial light-like trajectories verify the viability of the diagram. Coordinate dependencies of significant features, such as the horizon and radial mass scale, are clearly demonstrated on the diagram. The onset of a singularity at the origin is shown to open a new region in space-time that contains the interior of the black hole.
Relativistic Viscous Fluid Description of Microscopic Black Hole Wind
J. I. Kapusta
2001-05-25T23:59:59.000Z
Microscopic black holes explode with their temperature varying inversely as their mass. Such explosions would lead to the highest temperatures in the present universe, all the way to the Planck energy. Whether or not a quasi-stationary shell of matter undergoing radial hydrodynamic expansion surrounds such black holes is been controversial. In this paper relativistic viscous fluid equations are applied to the problem. It is shown that a self-consistent picture emerges of a fluid just marginally kept in local thermal equilibrium; viscosity is a crucial element of the dynamics.
Energy of Kerr-Newman Black-Holes and Gravitomagnetism
Marcelo Samuel Berman
2004-08-11T23:59:59.000Z
New formulae are obtained for the energy of K.N. b.h.'s that point out a gravitomagnetic energy effect. The results are valid for slowly or rapidly rotating black-holes. The expression of the energy density of Kerr-Newman back-holes in the slow rotation case, is obtained afterwards, and shown to be essentially positive. Subsequently,we show how to attain a "repulsive" gravitation (antigravitation) state identified with negative energy distribution contents in a limited region of space, without violating the Positive Energy Theorem.
Energy Associated with Schwarzschild Black Hole in a Magnetic Universe
S. S. Xulu
2000-01-29T23:59:59.000Z
In this paper we obtain the energy distribution associated with the Ernst space-time (geometry describing Schwarzschild black hole in Melvin's magnetic universe) in Einstein's prescription. The first term is the rest-mass energy of the Schwarzschild black hole, the second term is the classical value for the energy of the uniform magnetic field and the remaining terms in the expression are due to the general relativistic effect. The presence of the magnetic field is found to increase the energy of the system.
Black Hole Collisions, Analytic Continuation, and Cosmic Censorship
Dieter R. Brill
1995-03-27T23:59:59.000Z
Exact solutions of the Einstein-Maxwell equations that describe moving black holes in a cosmological setting are discussed with the aim of discovering the global structure and testing cosmic censorship. Continuation beyond the horizons present in these solutions is necessary in order to identify the global structure. Therefore the possibilities and methods of analytic extension of geometries are briefly reviewed. The global structure of the Reissner-Nordstr\\"om-de Sitter geometry is found by these methods. When several black holes are present, the exact solution is no longer everywhere analytic, but less smooth extensions satisfying the Einstein equations everywhere are possible. Some of these provide counterexamples to cosmic censorship.
Low energy 2+1 string gravity; black hole solutions
A. A. Garcia Diaz; G. Gutierrez Cano
2014-12-17T23:59:59.000Z
In this report a detailed derivation of the dynamical equations for an n dimensional heterotic string theory of the Horowitz type is carried out in the string frame and in the Einstein frame too. In particular, the dynamical equations of the three dimensional string theory are explicitly given. The relation of the Horowitz Welch and Horne Horowitz string black hole solution is exhibited. The Chan Mann charged dilaton solution is derived and the subclass of string solutions field is explicitly identified. The stationary generalization, via SL(2;R) transformations, of the static (2+1) Horne Horowitz string black hole solution is given.
On Brane Inflation Potentials and Black Hole Attractors
Adil Belhaj; Pablo Diaz; Mohamed Naciri; Antonio Segui
2007-11-16T23:59:59.000Z
We propose a new potential in brane inflation theory, which is given by the arctangent of the square of the scalar field. Then we perform an explicit computation for inflationary quantities. This potential has many nice features. In the small field approximation, it reproduces the chaotic and MSSM potentials. It allows one, in the large field approximation, to implement the attractor mechanism for bulk black holes where the geometry on the brane is de Sitter. In particular, we show, up to some assumptions, that the Friedman equation can be reinterpreted as a Schwarzschild black hole attractor equation for its mass parameter.
Do Supermassive Black Holes Exist at the Center of Galaxies?
J. W. Moffat
1998-03-22T23:59:59.000Z
Models of superdense star clusters at the center of galaxies are investigated to see whether such objects can be stable and long-lived based on evaporation and collision time-scales and stability criteria. We find that physically reasonable models of massive clusters of stellar remnants can exist with masses $\\geq 10^6 M_{\\odot}$, which could simulate black holes at the center of galaxies with large $M/L$ ratios and gas motions of order $\\geq 10^3$ km $s^{-1}$. It follows that the evidence is not conclusive for massive dark objects at the center of galaxies being black holes.
Thermodynamics of Schrödinger black holes with hyperscaling violation
J. Sadeghi; B. Pourhassan; F. Pourasadollah
2012-11-06T23:59:59.000Z
In this work, we follow Kim and Yamada (JHEP1107 (2011) 120) and utilize AdS in light-cone frame to derive thermodynamic and transport properties of two kinds of Schr\\"{o}dinger black holes with hyperscaling violation. In that case, we show entropy and temperature are depend on $\\theta$. In $\\theta=0$ we see our results are agree with the work of Kim and Yamada. We also construct R-charged black hole with hyperscaling violation and obtain thermodynamics and transport properties.
Isolated Horizons: A Generalization of Black Hole Mechanics
Abhay Ashtekar; Christopher Beetle; Stephen Fairhurst
1998-12-18T23:59:59.000Z
A set of boundary conditions defining a non-rotating isolated horizon are given in Einstein-Maxwell theory. A space-time representing a black hole which itself is in equilibrium but whose exterior contains radiation admits such a horizon . Physically motivated, (quasi-)local definitions of the mass and surface gravity of an isolated horizon are introduced. Although these definitions do not refer to infinity, the quantities assume their standard values in Reissner-Nordstrom solutions. Finally, using these definitions, the zeroth and first laws of black hole mechanics are established for isolated horizons.
Fate of Yang-Mills black hole in early Universe
Nakonieczny, Lukasz; Rogatko, Marek [Institute of Physics Maria Curie-Sklodowska University 20-031 Lublin, pl. Marii Curie-Sklodowskiej 1 (Poland)
2013-02-21T23:59:59.000Z
According to the Big Bang Theory as we go back in time the Universe becomes progressively hotter and denser. This leads us to believe that the early Universe was filled with hot plasma of elementary particles. Among many questions concerning this phase of history of the Universe there are questions of existence and fate of magnetic monopoles and primordial black holes. Static solution of Einstein-Yang-Mills system may be used as a toy model for such a black hole. Using methods of field theory we will show that its existence and regularity depend crucially on the presence of fermions around it.
Improvement of tap holes at Wakayama No. 5 blast furnace
Yamashita, M.; Kashiwada, M.; Shibuta, H. [Sumitomo Metal Industries, Ltd., Wakayama (Japan). Wakayama Steel Works
1995-12-01T23:59:59.000Z
The service life of blast furnaces, as the result of various improvement measures, has been extended from the conventional 5 to 7 years to 15 to 20 years. Wakayama No. 5 blast furnace adopted SiC bricks. Though SiC brick excelled in strength and durability, it has raised problems such as tap hole inside temperature lowering attributable to its high thermal conductivity, insufficient mud burning and gas blow-out. Nevertheless, various countermeasures described within have been taken against such problems, and as the result it has now become possible to maintain tap holes in stable conditions.
Supermassive Black Holes and the Evolution of Galaxies
D. Richstone; E. A. Ajhar; R. Bender; G. Bower; A. Dressler; S. M. Faber; A. V. Filippenko; K. Gebhardt; R. Green; L. C. Ho; J. Kormendy; T. Lauer; J. Magorrian; S. Tremaine
1998-10-23T23:59:59.000Z
Black holes, an extreme consequence of the mathematics of General Relativity, have long been suspected of being the prime movers of quasars, which emit more energy than any other objects in the Universe. Recent evidence indicates that supermassive black holes, which are probably quasar remnants, reside at the centers of most galaxies. As our knowledge of the demographics of these relics of a violent earlier Universe improve, we see tantalizing clues that they participated intimately in the formation of galaxies and have strongly influenced their present-day structure.
Repairs for damaged bolt holes in continuous fiber reinforced plastics
Copps, Kevin Daniel
1992-01-01T23:59:59.000Z
repair method for damaged bolt holes in such composites. Bolt holes in three types of graphite-epoxy were purposely damaged and then repaired. Each was tested to characterize its static and fatigue behavior. The tests used a special fixture to simulate... composite joints . Bearing-bypass ratio can change the failure mode of bolted composite joints 7 Drilling defects in graphite-epoxy coupons 12 26 The exit side of a IM7/8551-7A 18 ply tape coupon showing the damage due to drilling 27 9 Resin filled...
A photometric method to determine supermassive black hole masses
A. W. Graham; P. Erwin; N. Caon; I. Trujillo
2002-06-14T23:59:59.000Z
We report the discovery of a strong correlation between the shape of a bulge's light-profile and the mass of its central supermassive black hole (M_{bh}). We find that log(M_{bh}/M_{sun}) = 2.91(+/-0.38)log(n) + 6.37(+/-0.21), where `n' is the Sersic r^{1/n} shape index of the bulge. This correlation is marginally stronger than the relationship between the logarithm of the stellar velocity dispersion and log(M_{bh}) and has comparable scatter. It therefore offers a cheap (in terms of telescope time) alternative to estimating the masses of supermassive black holes.
Black Holes in 2+1 Teleparallel Theories of Gravity
A. A. Sousa; J. W. Maluf
2003-01-21T23:59:59.000Z
We apply the Hamiltonian formulation of teleparallel theories of gravity in 2+1 dimensions to a circularly symmetric geometry. We find a family of one-parameter black hole solutions. The BTZ solution fixes the unique free parameter of the theory. The resulting field equations coincide with the teleparallel equivalent of Einstein's three-dimensional equations. We calculate the gravitational energy of the black holes by means of the simple expression that arises in the Hamiltonian formulation and conclude that the resulting value is identical to that calculated by means of the Brown-York method.
Search for gravitational wave ringdowns from perturbed black holes in LIGO S4 data
Zucker, Michael E.
According to general relativity a perturbed black hole will settle to a stationary configuration by the emission of gravitational radiation. Such a perturbation will occur, for example, in the coalescence of a black hole ...
Supersymmetric Yang Mills Fields and Black Holes ; In Ten Dimensional Unified Field Theory
Ajay Patwardhan
2007-05-17T23:59:59.000Z
The Ten dimensional Unified field theory has a 4 dimensional Riemannian spacetime and six dimensional Calabi Yau space structure. The supersymmetric Yang Mills fields and black holes are solutions in these theories. The formation of primordial black holes in early universe, the collapse to singularity of stellar black holes, the Hawking evaporation of microscopic black holes in LHC are topics of observational and theoretical interest. The observation of gamma ray bursts and creation of spectrum of particles and radiation of dark and normal matter occur due to primordial and microscopic black holes. The approach to singularity in black hole interior solutions, require the Bogoliubov transforms of SUSY YM fields in black hole geometries; both during formation and in evaporation. The Hawking effect of radiating black holes is applicable for all the fields. Invariants can be defined to give the conditions for these processes.
Experimental Test of Hole-Coupled FEL Resonator Designs Using a CW-HeNe Laser
Leemans, W.P.
2011-01-01T23:59:59.000Z
Proc. 14 th International FEL Conference, Kobe, Japan, 23-24Test of Hole-Coupled FEL Resonator Designs Using a CW-HeNeuse of hole-coupling for FEL's are: I) reasonable coupling
Three-Dimensional Simulation of a Hole-Coupled FEL Oscillator
Krishnagopal, S.
2008-01-01T23:59:59.000Z
resonator in the presence of FEL gain, M.Xie and K. -J.Kim,Simulation of a Hole-Coupled FEL Oscillator S. KrishnagopalSimulation of a Hole-Coupled FEL Oscillator S. Krishnagopal,
Calibration and data reduction algorithms for non-conventional multi-hole pressure probes
Ramakrishnan, Vijay
2004-09-30T23:59:59.000Z
This thesis presents the development of calibration and data-reduction algorithms for non-conventional multi-hole pressure probes. The algorithms that have been developed for conventional 5- and 7-hole probes are not optimal ...
MEMS Materials and Temperature Sensors for Down Hole Geothermal System Monitoring
Wodin-Schwartz, Sarah
2013-01-01T23:59:59.000Z
Geothermal EnergyThe future of geothermal energy: Impact of enhanceddown-hole monitoring of geothermal energy systems. ASME 2011
Harley, Gabriel; Smith, David D; Dennis, Tim; Waldhauer, Ann; Kim, Taeseok; Cousins, Peter John
2013-11-19T23:59:59.000Z
Contact holes of solar cells are formed by laser ablation to accomodate various solar cell designs. Use of a laser to form the contact holes is facilitated by replacing films formed on the diffusion regions with a film that has substantially uniform thickness. Contact holes may be formed to deep diffusion regions to increase the laser ablation process margins. The laser configuration may be tailored to form contact holes through dielectric films of varying thickness.
Evaluation of hole quality and bit life in graphite epoxy composites using video scanning
Lednicky, Thomas Edward
1985-01-01T23:59:59.000Z
. Hough J (Chairman of Commit ee) D . R. M. Alexander (Member) ( e&/ Dr, J. Bo sford (Memb r) W. . Turner (Head o Department) December 1985 ABSTRACT EVALUATION OF HOLE QUALITY AND BIT LIFE IN GRAPHITE EPOXY COMPOSITES USING VIDEO SCANNING... extensively in graphite epoxy composite material. This evaluation was accomplished by measuring the hole quality and also the wear land development. Two methods were used to determine the hole quality on a computer vision system: the hole size...
Rotating charged hairy black hole in (2+1) dimensions and particle acceleration
J. Sadeghi; B. Pourhassan; H. Farahani
2013-10-26T23:59:59.000Z
In this paper we construct rotating charged hairy black hole in (2+1) dimensions for infinitesimal black hole charge and rotation parameters. Then we consider this black hole as particle accelerator and calculate the center-of-mass energy of two colliding test particles near the rotating charged hairy black hole in (2+1) dimensions. As we expected, the center-of-mass energy has infinite value.
Enhanced Hole Mobility in High Ge Content Asymmetrically Strained-SiGe p-MOSFETs
Chléirigh, C. Ni
The hole mobility characteristics of ?110? /(100)-oriented asymmetrically strained-SiGe p-MOSFETs are studied.
Arman Tursunov; Martin Kološ; Zden?k Stuchlík; Bobomurat Ahmedov
2014-09-18T23:59:59.000Z
We study the acceleration of an electric current-carrying and axially-symmetric string loop initially oscillating in the vicinity of a Schwarzschild black hole embedded in an external asymptotically uniform magnetic field. The plane of the string loop is orthogonal to the magnetic field lines and the acceleration of the string loop occurs due to the transmutation effect turning in the deep gravitational field the internal energy of the oscillating strings to the energy of their translational motion along the axis given by the symmetry of the black hole spacetime and the magnetic field. We restrict our attention to the motion of string loop with energy high enough, when it can overcome the gravitational attraction and escape to infinity. We demonstrate that for the current-carrying string loop the transmutation effect is enhanced by the contribution of the interaction between the electric current of the string loop and the external magnetic field and we give conditions that have to be fulfilled for an efficient acceleration. The Schwarzschild black hole combined with the strong external magnetic field can accelerate the current-carrying string loop up to the velocities close to the speed of light $v \\sim c$. Therefore, the string loop transmutation effect can potentially well serve as an explanation for acceleration of highly relativistic jets observed in microquasars and active galactic nuclei.
Iliffe, Thomas M.
Ostracoda of Moss Town Blue Hole, Great Exuma Island, Great Bahama Bank (Crustacea: Ostracoda Halocypridina, and one Cladocopina) are reported from 30 to 60 m depths in Moss Town Blue Hole, an ocean blue. The collection from Moss Town Blue Hole contained no new species, but five species had not been reported
Entropy bound of a charged object and electrostatic self-energy in black holes
B. Linet
1999-11-30T23:59:59.000Z
Without pretending to any rigour, we find a general expression of the electrostatic self-energy in static black holes with spherical symmetry. We determine the entropy bound of a charged object by assuming the existence of thermodynamics for these black holes. By combining these two results, we show that the entropy bound does not depend on the considered black hole.
Dark Energy Accretion onto a Black Hole in an Expanding Universe
Cheng-Yi Sun
2009-03-14T23:59:59.000Z
By using the solution describing a black hole embedded in the FLRW universe, we obtain the evolving equation of the black hole mass expressed in terms of the cosmological parameters. The evolving equation indicates that in the phantom dark energy universe the black hole mass becomes zero before the Big Rip is reached.
Holography, Gauge-gravity Connection and Black Hole Entropy Parthasarathi Majumdar,
;Created with pptalk Slide 2 Black holes : Extreme gravitation at work what lies beyond the `hori- zon' observationally unknown Inaccessibility apprehensions Turn to theory Black Holes from Newton's law ? Dark stars faster than c ? #12;Created with pptalk Slide 2 Black holes : Extreme gravitation at work what lies
Relative importance of radical families The "Ozone Hole"
Toohey, Darin W.
· Relative importance of radical families · The "Ozone Hole" · Introduction to heterogeneous chemistry Tuesday, March 8, 2011 #12;Review of important points so far Stratospheric ozone is only produced with these parameters Sir Sydney Chapman nearly got it right. He could account for the formation of the ozone layer
Black hole free energy during charged collapse: a numerical study
Hugues Beauchesne; Ariel Edery
2012-05-19T23:59:59.000Z
We perform a numerical investigation of the thermodynamics during the collapse of a charged (complex) scalar field to a Reissner-Nordstr\\"om (RN) black hole in isotropic coordinates. Numerical work on gravitational collapse in isotropic coordinates has recently shown that the negative of the total Lagrangian approaches the Helmholtz free energy F= E-TS of a Schwarzschild black hole at late times of the collapse (where E is the black hole mass, T the temperature and S the entropy). The relevant thermodynamic potential for the RN black hole is the Gibbs free energy G=E-TS-$\\Phi_H$ Q where Q is the charge and $\\Phi_H$ the electrostatic potential at the outer horizon. In charged collapse, there is a large outgoing matter wave which prevents the exterior from settling quickly to a static state. However, the interior region is not affected significantly by the wave. We find numerically that the interior contribution to the Gibbs free energy is entirely gravitational and accumulates in a thin shell just inside the horizon. The entropy is gravitational in origin and one observes dynamically that it resides on the horizon. We also compare the numerical value of the interior Lagrangian to the expected analytical value of the interior Gibbs free energy for different initial states and we find that they agree to within 10-13%. The two values are approaching each other so that their difference decreases with more evolution time.
Conserved Charges and Thermodynamics of the Spinning Goedel Black Hole
Barnich, Glenn; Compere, Geoffrey [Physique Theorique et Mathematique, Universite Libre de Bruxelles, and International Solvay Institutes, Campus Plaine C.P. 231, B-1050 Brussels (Belgium)
2005-07-15T23:59:59.000Z
We compute the mass, angular momenta, and charge of the Goedel-type rotating black hole solution to five-dimensional minimal supergravity. A generalized Smarr formula is derived, and the first law of thermodynamics is verified. The computation rests on a new approach to conserved charges in gauge theories that allows for their computation at finite radius.
Steady and unsteady calibration of multi-hole probes
Johansen, Espen S
1998-01-01T23:59:59.000Z
properties like the density and viscosity. The algorithm utilizes a local least-squares modeling technique and has been tested on 4 novel miniature 7-hole probes that have been calibrated at NASA Langley Flow Modeling and Control Branch for the entire...
Reissner-Nordstrom black hole in dark energy background
Ngangbam Ishwarchandra; Ng. Ibohal; K. Yugindro Singh
2014-11-29T23:59:59.000Z
In this paper we propose a stationary solution of Einstein's field equations describing Reissner-Nordstrom black hole in dark energy background. It is to be regarded as the Reissner-Nordstrom black hole is embedded into the dark energy solution producing Reissner-Nordstrom-dark energy black hole. We find that the space-time geometry of Reissner-Nordstrom-dark energy solution is Petrov type $D$ in the classification of space-times. It is also shown that the embedded space-time possesses an energy-momentum tensor of the electromagnetic field interacting with the dark energy having negative pressure. We find the energy-momentum tensor for dark energy violates the the strong energy condition due to the negative pressure, whereas that of the electromagnetic field obeys the strong energy condition. It is shown that the time-like vector field for an observer in the Reissner-Nordstrom-dark energy space is expanding, accelerating, shearing and non-rotating. We investigate the surface gravity of the horizons for the embedded dark energy black hole. The characteristic properties of relativistic dark energy based on the de Sitter solution is discussed in an appendix.
Comment on "Formation of Holes in Alkanethiol Monolayers on Gold"
Myrick, Michael Lenn
microscopy (STM) images of al- kanethiolate monolayers on gold, one type of defect appears which does concentration.1 Fifth, the evolution of the holes appears to cease once the self-assembled monolayer (SAM) has the surface. They are not usually found very near existing step defects, and time-resolved STM images
Gravitational Self-Energy and Black Holes in Newtonian Physics
G. Dillon
2013-02-15T23:59:59.000Z
A definition of a Newtonian black hole is possible which incorporates the mass-energy equivalence from special relativity. However, exploiting a double spherical shell model, it will be shown that the ensuing gravitational self-energy and mass renormalization prevent the formation of such an object.
Bulk emission of scalars by a rotating black hole
M. Casals; S. R. Dolan; P. Kanti; E. Winstanley
2008-07-17T23:59:59.000Z
We study in detail the scalar-field Hawking radiation emitted into the bulk by a higher-dimensional, rotating black hole. We numerically compute the angular eigenvalues, and solve the radial equation of motion in order to find transmission factors. The latter are found to be enhanced by the angular momentum of the black hole, and to exhibit the well-known effect of superradiance. The corresponding power spectra for scalar fields show an enhancement with the number of dimensions, as in the non-rotating case. We compute the total mass loss rate of the black hole for a variety of black-hole angular momenta and bulk dimensions, and find that, in all cases, the bulk emission remains significantly smaller than the brane emission. The angular-momentum loss rate is also computed and found to have a smaller value in the bulk than on the brane. We present accurate bulk-to-brane emission ratios for a range of scenarios.
No Scalar Hair Theorem for a Charged Spherical Black Hole
N. Banerjee; S. Sen
1998-08-11T23:59:59.000Z
This paper consolidates noscalar hair theorem for a charged spherically symmetric black hole in four dimension in general relativity as well as in all scalar tensor theories, both minimally and nonminimally coupled, when the effective Newtonian constant of gravity is positive. However, there is an exception when the matter field itself is coupled to the scalar field, such as in dilaton gravity.
Primordial black holes from temporally enhanced curvature perturbation
Teruaki Suyama; Yi-Peng Wu; Jun'ichi Yokoyama
2014-06-02T23:59:59.000Z
Scalar field with generalized kinetic interactions metamorphoses depending on its field value, ranging from cosmological constant to stiff matter. We show that such a scalar field can give rise to temporal enhancement of the curvature perturbation in the primordial Universe, leading to efficient production of primordial black holes while the enhancement persists. If the inflation energy scale is high, those mini-black holes evaporate by the Hawking radiation much before Big Bang nucleosynthesis and the effective reheating of the Universe is achieved by the black hole evaporation. Dominance of PBHs and the reheating by their evaporation modify the expansion history of the primordial Universe. This results in a characteristic feature of the spectrum of primordial tensor modes in the DECIGO frequency band, opening an interesting possibility of testing PBH reheating scenario by measuring the primordial tensor modes. If the inflation energy scale is low, the PBH mass can be much larger than the solar mass. In this case, PBH is an interesting candidate for seeds for supermassive black holes residing in present galaxies.
Neutron Hole States of Mo-93,95
Bindal, P. K.; Youngblood, David H.; Kozub, R. L.
1977-01-01T23:59:59.000Z
- topes but less than half is observed for '"Mo. The hole strength distributions for l =1 and 4 are displayed in Fig. 10 for all the Mo isotopes. It is apparent from this figure that the states corres- ponding to lgg/2 2Py/2 and 2P, /, orbitals, which...
Black hole mergers: do gas discs lead to spin alignment?
Giuseppe Lodato; Davide Gerosa
2012-11-01T23:59:59.000Z
In this Letter we revisit arguments suggesting that the Bardeen-Petterson effect can coalign the spins of a central supermassive black hole binary accreting from a circumbinary (or circumnuclear) gas disc. We improve on previous estimates by adding the dependence on system parameters, and noting that the nonlinear nature of warp propagation in a thin viscous disc affects alignment. This reduces the disc's ability to communicate the warp, and can severely reduce the effectiveness of disc-assisted spin alignment. We test our predictions with a Monte Carlo realization of random misalignments and accretion rates and we find that the outcome depends strongly on the spin magnitude. We estimate a generous upper limit to the probability of alignment by making assumptions which favour it throughout. Even with these assumptions, about 40% of black holes with $a \\gtrsim 0.5$ do not have time to align with the disc. If the residual misalignment is not small and it is maintained down to the final coalescence phase this can give a powerful recoil velocity to the merged hole. Highly spinning black holes are thus more likely of being subject to strong recoils, the occurrence of which is currently debated.
Dynamically self-regular quantum harmonic black holes
Spallucci, Euro
2015-01-01T23:59:59.000Z
The recently proposed UV self-complete quantum gravity program is a new and very interesting way to envision Planckian/trans-Planckian physics. in this new framework, high energy scattering is dominated by the creation of micro black holes, and it is experimentally impossible to probe distances shorter than the horizon radius. In this letter we present a model which realizes this idea through the creation of self-regular quantum black holes admitting a minimal size extremal configuration. Their radius provides a dynamically generated minimal length acting as a universal short-distance cut-off. We propose a quantisation scheme for this new kind of microscopic objects based on a Bohr-like approach, which does not require a detailed knowledge of quantum gravity. The resulting black hole quantum picture resembles the energy spectrum of a quantum harmonic oscillator. The mass of the extremal configuration plays the role of zero-point energy. Large quantum number re-establish the classical black hole description. F...
No hair theorems for stationary axisymmetric black holes
Sourav Bhattacharya; Amitabha Lahiri
2011-05-20T23:59:59.000Z
We present a non-perturbative proof of the no hair theorems corresponding to scalar and Proca fields for stationary axisymmetric de Sitter black hole spacetimes. Our method also applies to asymptotically flat and under a reasonable assumption, to asymptotically anti-de Sitter spacetimes.
Graphene oxide hole transport layers for large area, high efficiency organic solar cells
Smith, Chris T. G.; Rhodes, Rhys W.; Beliatis, Michail J.; Imalka Jayawardena, K. D. G.; Rozanski, Lynn J.; Mills, Christopher A.; Silva, S. Ravi P., E-mail: s.silva@surrey.ac.uk [Advanced Technology Institute, University of Surrey, Guildford GU2 7XH (United Kingdom)
2014-08-18T23:59:59.000Z
Graphene oxide (GO) is becoming increasingly popular for organic electronic applications. We present large active area (0.64?cm{sup 2}), solution processable, poly[[9-(1-octylnonyl)-9H-carbazole-2,7-diyl]-2,5-thiophenediyl-2,1, 3-benzothiadiazole-4,7-diyl-2,5-thiophenediyl]:[6,6]-Phenyl C{sub 71} butyric acid methyl ester (PCDTBT:PC{sub 70}BM) organic photovoltaic (OPV) solar cells, incorporating GO hole transport layers (HTL). The power conversion efficiency (PCE) of ?5% is the highest reported for OPV using this architecture. A comparative study of solution-processable devices has been undertaken to benchmark GO OPV performance with poly(3,4-ethylenedioxythiophene) poly(styrenesulfonate) (PEDOT:PSS) HTL devices, confirming the viability of GO devices, with comparable PCEs, suitable as high chemical and thermal stability replacements for PEDOT:PSS in OPV.
Atmospheric Oxygen Binding and Hole Doping in Deformed Graphene on a SiO2 Substrate
Sunmin Ryu; Li Liu; Stephane Berciaud; Young-Jun Yu; Haitao Liu; Philip Kim; George W. Flynn; Louis E. Brus
2010-11-13T23:59:59.000Z
Using micro-Raman spectroscopy and scanning tunneling microscopy, we study the relationship between structural distortion and electrical hole doping of graphene on a silicon dioxide substrate. The observed upshift of the Raman G band represents charge doping and not compressive strain. Two independent factors control the doping: (1) the degree of graphene coupling to the substrate, and (2) exposure to oxygen and moisture. Thermal annealing induces a pronounced structural distortion due to close coupling to SiO2 and activates the ability of diatomic oxygen to accept charge from graphene. Gas flow experiments show that dry oxygen reversibly dopes graphene; doping becomes stronger and more irreversible in the presence of moisture and over long periods of time. We propose that oxygen molecular anions are stabilized by water solvation and electrostatic binding to the silicon dioxide surface.
A Strong Correlation between Circumnuclear Dust and Black Hole Accretion in Early-Type Galaxies
Ramiro D. Simões Lopes; Thaisa Storchi-Bergmann; Maria de Fátima O. Saraiva; Paul Martini
2006-10-12T23:59:59.000Z
We present a detailed investigation of the incidence of circumnuclear dust structure in a large, well-matched sample of early-type galaxies with and without Active Galactic Nuclei (AGN). All 34 early-type AGN hosts in our sample have circumnuclear dust, while dust is only observed in 26% (nine) of a pair-matched sample of 34 early-type, inactive galaxies. This result demonstrates a strong correlation between the presence of circumnuclear dust and accretion onto the central, supermassive black hole in elliptical and lenticular galaxies. This correlation is not present at later Hubble types, where a sample of 31 active and 31 inactive galaxies all contain circumnuclear dust. These archival, HST observations reveal a wide range of mostly chaotic dust morphologies. Current estimates suggest the dust settling or destruction time is on order of 10^8 years and therefore the presence of dust in ~ 50% of early-type galaxies requires frequent replenishment and similarly frequent fueling of their central, supermassive black holes. The observed dust could be internally-produced (via stellar winds) or externally-accreted, although there are observational challenges for both of these scenarios. Our analysis also reveals that approximately a third of the early-type galaxies without circumnuclear dust have nuclear stellar disks. These nuclear stellar disks may provide a preferred kinematic axis to externally-accreted material and this material may in turn form new stars in these disks. The observed incidence of nuclear stellar disks and circumnuclear dust suggests that episodic replenishment of nuclear stellar disks occurs and is approximately concurrent with the fueling of the central AGN.
Croatian Black Hole School 2010 lecture notes on IMBHs in GCs
Mario Pasquato
2010-08-26T23:59:59.000Z
Black holes are fascinating objects. As a class of solutions to the Einstein equations they have been studied a great deal, yielding a wealth of theoretical results. But do they really exist? What do astronomers really mean when they claim to have observational evidence of their existence? To answer these questions, I will focus on a particular range of black-hole masses, approximately from 100 to 10000 solar masses. Black holes of this size are named Intermediate Mass Black Holes (IMBHs) and their existence is still heavily disputed, so they will be perfect for illustrating the observational challenges faced by a black hole hunter
Phase transition between non-extremal and extremal Reissner-Nordström black holes
Yun Soo Myung
2008-03-11T23:59:59.000Z
We discuss the phase transition between non-extremal and extremal Reissner-Nordstr\\"om black holes. This transition is considered as the $T \\to 0$ limit of the transition between the non-extremal and near-extremal black holes. We show that an evaporating process from non-extremal black hole to extremal one is possible to occur, but its reverse process is not possible to occur because of the presence of the maximum temperature. Furthermore, it is shown that the Hawking-Page phase transition between small and large black holes unlikely occurs in the AdS Reissner-Nordstr\\"om black holes.
Phantom energy accretion onto a black hole in Horava Lifshitz gravity
G. Abbas
2013-03-27T23:59:59.000Z
In this Letter, we examine the phantom energy accretion onto a Kehagias-Sfetsos black hole in Ho$\\check{r}$ava Lifshitz gravity. To discuss the accretion process onto the black hole, the equations of phantom flow near the black hole have been derived. It is found that mass of the black hole decreases because of phantom accretion. We discuss the conditions for critical accretion. Graphically, it has been found that the critical accretion phenomena is possible for different values of parameters. The results for the Schwarzschild black hole can be recovered in the limiting case.
Stellar and Intermediate-Mass Black Holes in the Milky Way and Nearby Galaxies
Irwin, Jimmy [Department of Physics and Astronomy, University of Alabama, Box 870324, Tuscaloosa, AL 35487-0324 (United States)
2010-08-09T23:59:59.000Z
With the advent of high resolution X-ray telescopes, the ability to identify extragalactic black holes has greatly enhanced our understanding of massive compact objects, as we are no longer limited to the rather meager Milky Way black hole population. The greatly increased numbers have opened up opportunities to find new modes of compact object accretion and potentially long-sought evidence for intermediate-mass black holes. In this lecture series, the current state of knowledge of stellar- and intermediate-mass black holes is reviewed, particularly in regards to black hole populations in external galaxies.
Characterizing asymptotically anti-de Sitter black holes with abundant stable gauge field hair
Ben L. Shepherd; Elizabeth Winstanley
2012-06-25T23:59:59.000Z
In the light of the "no-hair" conjecture, we revisit stable black holes in su(N) Einstein-Yang-Mills theory with a negative cosmological constant. These black holes are endowed with copious amounts of gauge field hair, and we address the question of whether these black holes can be uniquely characterized by their mass and a set of global non-Abelian charges defined far from the black hole. For the su(3) case, we present numerical evidence that stable black hole configurations are fixed by their mass and two non-Abelian charges. For general N, we argue that the mass and N-1 non-Abelian charges are sufficient to characterize large stable black holes, in keeping with the spirit of the "no-hair" conjecture, at least in the limit of very large magnitude cosmological constant and for a subspace containing stable black holes (and possibly some unstable ones as well).
Laser frequency stabilization based on steady-state spectral-hole burning in Eu$^{3+}$:Y$_2$SiO$_5$
Cook, Shon; Leibrandt, David R
2015-01-01T23:59:59.000Z
We present and analyze a method of laser frequency stabilization via steady-state patterns of spectral holes in Eu$^{3+}$:Y$_2$SiO$_5$. Three regions of spectral holes are created, spaced in frequency by the ground state hyperfine splittings of $~^{151}$Eu$^{3+}$. The absorption pattern is shown not to degrade after days of laser frequency stabilization. An optical frequency comparison of a laser locked to such a steady-state spectral-hole pattern with an independent cavity-stabilized laser and a Yb optical lattice clock demonstrates a spectral-hole fractional frequency instability of $1.0\\times10^{-15}~ \\tau^{-\\frac{1}{2}}$ that averages to $8.5^{+4.8}_{-1.8}\\times10^{-17}$ at $\\tau = 73$ s. Residual amplitude modulation at the frequency of the RF drive applied to the fiber-coupled electro-optic modulator is reduced to less than $1\\times10^{-6}$ fractional amplitude modulation at $\\tau>$ 1 s by an active servo. The contribution of residual amplitude modulation to the laser frequency instability is further re...
Liu Yi; D. R. Jiang
2006-12-11T23:59:59.000Z
In an examination of the relationship between the black hole mass and stellar velocity dispersion in radio-loud active galactic nuclei (AGNs), we studied two effects which may cause uncertainties in the black hole mass estimates of radio-loud AGNs: the relativistic beaming effect on the observed optical continuum radiation and the orientation effect on the broad emission line width. After correcting these two effects, we re-examined the relation between black hole mass and stellar velocity dispersion which derived from [OIII] line width for a sample of radio-loud and radio-quiet AGNs, and found the relation for radio-loud AGNs still deviated from that for nearby normal galaxies and radio-quiet AGNs. We also found there is no significant correlation between radio jet power and narrow [OIII] line width, indicating absence of strong interaction between radio jet and narrow line region. It may be that the deviation of the relation between black hole mass and stellar velocity dispersion of radio-loud AGNs is intrinsic, or that the [OIII] line width is not a good indicator of stellar velocity dispersion for radio-loud AGNs.
Accretion Discs Around Black Holes: Developement of Theory
G. S. Bisnovatyi-Kogan
1999-11-11T23:59:59.000Z
Standard accretion disk theory is formulated which is based on the local heat balance. The energy produced by a turbulent viscous heating is supposed to be emitted to the sides of the disc. Sources of turbulence in the accretion disc are connected with nonlinear hydrodynamic instability, convection, and magnetic field. In standard theory there are two branches of solution, optically thick, and optically thin. Advection in accretion disks is described by the differential equations what makes the theory nonlocal. Low-luminous optically thin accretion disc model with advection at some suggestions may become advectively dominated, carrying almost all the energy inside the black hole. The proper account of magnetic filed in the process of accretion limits the energy advected into a black hole, efficiency of accretion should exceed $\\sim 1/4$ of the standard accretion disk model efficiency.