skip to main content
OSTI.GOV title logo U.S. Department of Energy
Office of Scientific and Technical Information

Title: Accretion shocks in the laboratory: Design of an experiment to study star formation

Authors:
; ; ;
Publication Date:
Sponsoring Org.:
USDOE
OSTI Identifier:
1397409
Grant/Contract Number:
NA0002956
Resource Type:
Journal Article: Publisher's Accepted Manuscript
Journal Name:
High Energy Density Physics
Additional Journal Information:
Journal Volume: 23; Journal Issue: C; Related Information: CHORUS Timestamp: 2017-10-04 21:05:17; Journal ID: ISSN 1574-1818
Publisher:
Elsevier
Country of Publication:
Netherlands
Language:
English

Citation Formats

Young, R. P., Kuranz, C. C., Drake, R. P., and Hartigan, P.. Accretion shocks in the laboratory: Design of an experiment to study star formation. Netherlands: N. p., 2017. Web. doi:10.1016/j.hedp.2017.01.004.
Young, R. P., Kuranz, C. C., Drake, R. P., & Hartigan, P.. Accretion shocks in the laboratory: Design of an experiment to study star formation. Netherlands. doi:10.1016/j.hedp.2017.01.004.
Young, R. P., Kuranz, C. C., Drake, R. P., and Hartigan, P.. Thu . "Accretion shocks in the laboratory: Design of an experiment to study star formation". Netherlands. doi:10.1016/j.hedp.2017.01.004.
@article{osti_1397409,
title = {Accretion shocks in the laboratory: Design of an experiment to study star formation},
author = {Young, R. P. and Kuranz, C. C. and Drake, R. P. and Hartigan, P.},
abstractNote = {},
doi = {10.1016/j.hedp.2017.01.004},
journal = {High Energy Density Physics},
number = C,
volume = 23,
place = {Netherlands},
year = {Thu Jun 01 00:00:00 EDT 2017},
month = {Thu Jun 01 00:00:00 EDT 2017}
}

Journal Article:
Free Publicly Available Full Text
Publisher's Version of Record at 10.1016/j.hedp.2017.01.004

Citation Metrics:
Cited by: 1work
Citation information provided by
Web of Science

Save / Share:
  • We present a measurement of the average supermassive black hole accretion rate (BHAR) as a function of the star formation rate (SFR) for galaxies in the redshift range 0.25 < z < 0.8. We study a sample of 1767 far-IR-selected star-forming galaxies in the 9 deg{sup 2} Booetes multi-wavelength survey field. The SFR is estimated using 250 {mu}m observations from the Herschel Space Observatory, for which the contribution from the active galactic nucleus (AGN) is minimal. In this sample, 121 AGNs are directly identified using X-ray or mid-IR selection criteria. We combined these detected AGNs and an X-ray stacking analysismore » for undetected sources to study the average BHAR for all of the star-forming galaxies in our sample. We find an almost linear relation between the average BHAR (in M{sub Sun} yr{sup -1}) and the SFR (in M{sub Sun} yr{sup -1}) for galaxies across a wide SFR range 0.85 < log SFR < 2.56: log BHAR = (- 3.72 {+-} 0.52) + (1.05 {+-} 0.33)log SFR. This global correlation between SFR and average BHAR is consistent with a simple picture in which SFR and AGN activity are tightly linked over galaxy evolution timescales.« less
  • The formation and evolution of the circumstellar disk in unmagnetized molecular clouds is investigated using three-dimensional hydrodynamic simulations from the prestellar core until the end of the main accretion phase. In collapsing cloud cores, the first (adiabatic) core with a size of {approx}>3 AU forms prior to the formation of the protostar. At its formation, the first core has a thick disk-like structure and is mainly supported by the thermal pressure. After the protostar formation, it decreases the thickness gradually and becomes supported by the centrifugal force. We found that the first core is a precursor of the circumstellar diskmore » with a size of >3 AU. This means that unmagnetized protoplanetary disk smaller than <3 AU does not exist. Reflecting the thermodynamics of the collapsing gas, at the protostar formation epoch, the first core (or the circumstellar disk) has a mass of {approx}0.005-0.1 M{sub sun}, while the protostar has a mass of {approx}10{sup -3} M{sub sun}. Thus, just after the protostar formation, the circumstellar disk is about 10-100 times more massive than the protostar. In the main accretion phase that lasts for {approx}10{sup 5} yr, the circumstellar disk mass initially tends to dominate the protostellar mass. Such a massive disk is unstable to gravitational instability and tends to show fragmentation. Our calculations indicate that the low-mass companions may form in the circumstellar disk in the main accretion phase. In addition, the mass accretion rate onto the protostar shows a strong time variability that is caused by the torque from the low-mass companions and/or the spiral arms in the circumstellar disk. Such variability provides an important signature for detecting the substellar mass companion in the circumstellar disk around very young protostars.« less
  • The stability properties of a self-gravitating gas layer depend critically on the large-scale shape of the layer. While a plane-parallel sheet essentially self-stabilizes against all but large-scale perturbations, by always providing restoring forces toward the midplane, a curved layer possesses a preferred direction of gravity that gives rise to self-made Rayleigh-Taylor instabilities. This difference leads, as we demonstrate in the present paper by a self-consistent stability analysis of the cylindrical gas shell as an example, to growth of perturbations at all wavelengths, with the smallest modes growing fastest. Curved gas sheets will therefore break up into masses much too smallmore » to subsequently form stars. The effect is enhanced in the presence of a central mass, causing ''external'' Rayleigh-Taylor instability. We discuss possible limits to growth on small scales by considering both viscosity and radiaiton pressure from a central object.« less
  • We use a deep Chandra observation to examine the structure of the hot intra-group medium of the compact group of galaxies Stephan's Quintet. The group is thought to be undergoing a strong dynamical interaction as an interloper, NGC 7318b, passes through the group core at {approx}850kms{sup -1}. Previous studies have interpreted a bright ridge of X-ray and radio continuum emission as the result of shock heating, with support from observations at other wavelengths. We find that gas in this ridge has a similar temperature ({approx}0.6 keV) and abundance ({approx}0.3 Z {sub sun}) to the surrounding diffuse emission, and that amore » hard emission component is consistent with that expected from high-mass X-ray binaries associated with star formation in the ridge. The cooling rate of gas in the ridge is consistent with the current star formation rate, suggesting that radiative cooling is driving the observed star formation. The lack of a high-temperature gas component is used to place constraints on the nature of the interaction and shock, and we find that an oblique shock heating a pre-existing filament of H I may be the most likely explanation of the X-ray gas in the ridge. The mass of hot gas in the group is roughly equal to the deficit in observed H I mass compared to predictions, but only {approx}2% of the gas is contained in the ridge. The hot gas component is too extended to have been heated by the current interaction, strongly suggesting that it must have been heated during previous dynamical encounters.« less