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Title: INSIGHTS INTO THE HIGH-ENERGY {gamma}-RAY EMISSION OF MARKARIAN 501 FROM EXTENSIVE MULTIFREQUENCY OBSERVATIONS IN THE FERMI ERA

Journal Article · · Astrophysical Journal
 [1]; ; ; ; ; ; ; ; ;  [2]; ; ; ;  [3];  [4];  [5];  [6];  [7];  [8]
  1. Space Science Division, Naval Research Laboratory, Washington, DC 20375 (United States)
  2. W. W. Hansen Experimental Physics Laboratory, Kavli Institute for Particle Astrophysics and Cosmology, Department of Physics and SLAC National Accelerator Laboratory, Stanford University, Stanford, CA 94305 (United States)
  3. Istituto Nazionale di Fisica Nucleare, Sezione di Pisa, I-56127 Pisa (Italy)
  4. Laboratoire AIM, CEA-IRFU/CNRS/Universite Paris Diderot, Service d'Astrophysique, CEA Saclay, 91191 Gif sur Yvette (France)
  5. Istituto Nazionale di Fisica Nucleare, Sezione di Trieste, I-34127 Trieste (Italy)
  6. Rice University, Department of Physics and Astronomy, MS-108, P. O. Box 1892, Houston, TX 77251 (United States)
  7. Istituto Nazionale di Fisica Nucleare, Sezione di Padova, I-35131 Padova (Italy)
  8. Istituto Nazionale di Fisica Nucleare, Sezione di Perugia, I-06123 Perugia (Italy)
+ Show Author Affiliations

We report on the {gamma}-ray activity of the blazar Mrk 501 during the first 480 days of Fermi operation. We find that the average Large Area Telescope (LAT) {gamma}-ray spectrum of Mrk 501 can be well described by a single power-law function with a photon index of 1.78 {+-} 0.03. While we observe relatively mild flux variations with the Fermi-LAT (within less than a factor of two), we detect remarkable spectral variability where the hardest observed spectral index within the LAT energy range is 1.52 {+-} 0.14, and the softest one is 2.51 {+-} 0.20. These unexpected spectral changes do not correlate with the measured flux variations above 0.3 GeV. In this paper, we also present the first results from the 4.5 month long multifrequency campaign (2009 March 15-August 1) on Mrk 501, which included the Very Long Baseline Array (VLBA), Swift, RXTE, MAGIC, and VERITAS, the F-GAMMA, GASP-WEBT, and other collaborations and instruments which provided excellent temporal and energy coverage of the source throughout the entire campaign. The extensive radio to TeV data set from this campaign provides us with the most detailed spectral energy distribution yet collected for this source during its relatively low activity. The average spectral energy distribution of Mrk 501 is well described by the standard one-zone synchrotron self-Compton (SSC) model. In the framework of this model, we find that the dominant emission region is characterized by a size {approx}<0.1 pc (comparable within a factor of few to the size of the partially resolved VLBA core at 15-43 GHz), and that the total jet power ({approx_equal}10{sup 44} erg s{sup -1}) constitutes only a small fraction ({approx}10{sup -3}) of the Eddington luminosity. The energy distribution of the freshly accelerated radiating electrons required to fit the time-averaged data has a broken power-law form in the energy range 0.3 GeV-10 TeV, with spectral indices 2.2 and 2.7 below and above the break energy of 20 GeV. We argue that such a form is consistent with a scenario in which the bulk of the energy dissipation within the dominant emission zone of Mrk 501 is due to relativistic, proton-mediated shocks. We find that the ultrarelativistic electrons and mildly relativistic protons within the blazar zone, if comparable in number, are in approximate energy equipartition, with their energy dominating the jet magnetic field energy by about two orders of magnitude.

OSTI ID:
21567509
Journal Information:
Astrophysical Journal, Vol. 727, Issue 2; Other Information: DOI: 10.1088/0004-637X/727/2/129; ISSN 0004-637X
Country of Publication:
United States
Language:
English

References (124)

The Burst Alert Telescope (BAT) on the SWIFT Midex Mission journal October 2005
The Swift X-Ray Telescope journal October 2005
Improving the performance of the single-dish Cherenkov telescope MAGIC through the use of signal timing journal January 2009
On characterizing the variability properties of X-ray light curves from active galaxies journal November 2003
On the fate of gas accreting at a low rate on to a black hole journal February 1999
Rapid variability in the synchrotron self-Compton model for blazars journal July 1999
Particle acceleration by ultrarelativistic shocks: theory and simulations journal December 2001
Swift observations of the very intense flaring activity of Mrk 421 during 2006. I. Phenomenological picture of electron acceleration and predictions for MeV/GeV emission journal April 2009
The GASP-WEBT monitoring of 3C 454.3 during the 2008 optical-to-radio and γ-ray outburst journal August 2009
Radio monitoring of a sample of X-and $\vec{\gamma}$-ray loud blazars journal December 2001
Low power BL Lacertae objects and the blazar sequence: Clues on the particle acceleration process journal May 2002
Implications of cosmological gamma-ray absorption: II. Modification of gamma-ray spectra journal January 2004
Log-parabolic spectra and particle acceleration in the BL Lac object Mkn 421: Spectral analysis of the complete BeppoSAX wide band X-ray data set journal December 2003
Log-parabolic spectra and particle acceleration in blazars: II. The BeppoSAX wide band X-ray spectra of Mkn 501 journal July 2004
Host galaxy subtraction of TeV candidate BL Lacertae objects journal September 2007
Multifrequency monitoring of the blazar 0716+714 during the GASP-WEBT-AGILE campaign of 2007 journal February 2008
Extragalactic optical-infrared background radiation, its time evolution and the cosmic photon-photon opacity journal June 2008
BVR photometry of comparison stars in selected blazar fields : II. Photometric sequences for 9 quasars journal June 1998
Survey of instantaneous 1-22 GHz spectra of 550 compact extragalactic objects with declinations from $-30^\circ$ to $+43^\circ$ journal November 1999
VHE γ-ray spectral properties of the blazars Mrk 501 and Mrk 421 from CAT observations in 1997 and 1998 conference January 2000
Ultraviolet photometry from the Orbiting Astronomical Observatory. XXVI - Energy distributions of seven early-type galaxies and the central bulge of M31 journal February 1979
Accurate formula for the self-Compton X-ray flux density from a uniform, spherical, compact radio source journal January 1983
The discrete correlation function - A new method for analyzing unevenly sampled variability data journal October 1988
Relativistic magnetosonic shock waves in synchrotron sources - Shock structure and nonthermal acceleration of positrons journal May 1992
Nonthermal electron-positron pair production and the 'universal' X-ray spectrum of active galactic nuclei journal July 1985
Advection-dominated accretion: A self-similar solution journal June 1994
ASCA Observations of Seyfert 1 Galaxies. I. Data Analysis, Imaging, and Timing journal February 1997
Maps of Dust Infrared Emission for Use in Estimation of Reddening and Cosmic Microwave Background Radiation Foregrounds journal June 1998
High‐Energy Emission from the TeV Blazar Markarian 501 during Multiwavelength Observations in 1996 journal March 1999
Correlated Intense X‐Ray and TeV Activity of Markarian 501 in 1998 June journal July 2000
Particle Acceleration at Ultrarelativistic Shocks: An Eigenfunction Method journal October 2000
Multiwavelength Observations of a Flare from Markarian 501 journal October 1997
The T[CLC]e[/CLC]V Spectrum of Markarian 501 journal July 1998
The Third EGRET Catalog of High‐Energy Gamma‐Ray Sources journal July 1999
Correcting for the Effects of Interstellar Extinction journal January 1999
The TeV Energy Spectrum of Markarian 501 Measured with the Stereoscopic Telescope System of HEGRA during 1998 and 1999 journal January 2001
Theoretical Implications from the Spectral Evolution of Markarian 501 Observed with BeppoSAX journal June 2001
Characteristic X‐Ray Variability of TeV Blazars: Probing the Link between the Jet and the Central Engine journal October 2001
Energetics of TeV Blazars and Physical Constraints on Their Emission Regions journal January 2002
X‐Ray Spectral Variability and Rapid Variability of the Soft X‐Ray Spectrum Seyfert 1 Galaxies Arakelian 564 and Ton S180 journal April 2002
The Subluminal Parsec-Scale Jet of Markarian 501 journal November 2002
Cosmic‐Ray Acceleration at Relativistic Shock Waves with a “Realistic” Magnetic Field Structure journal August 2004
The Swift Gamma‐Ray Burst Mission journal August 2004
A Multiwavelength View of the TeV Blazar Markarian 421: Correlated Variability, Flaring, and Spectral Evolution journal September 2005
Long‐Term X‐Ray and TeV Variability of Mrk 501 journal July 2006
Temporal Evolution of Pair Attenuation Signatures in Gamma‐Ray Burst Spectra journal October 2006
Heating and Nonthermal Particle Acceleration in Relativistic, Transverse Magnetosonic Shock Waves in Proton‐Electron‐Positron Plasmas journal December 2006
Variable Very High Energy γ‐Ray Emission from Markarian 501 journal November 2007
The Swift BAT X‐Ray Survey. III. X‐Ray Spectra and Statistical Properties journal January 2008
3C 454.3 Reveals the Structure and Physics of Its “Blazar Zone” journal March 2008
VERITAS Observations of the γ‐Ray Binary LS I +61 303 journal June 2008
Synchrotron Self‐Compton Analysis of TeV X‐Ray‐Selected BL Lacertae Objects journal October 2008
A Multizone Model for Simulating the High‐Energy Variability of TeV Blazars journal December 2008
Mojave: Monitoring of jets in Active Galactic Nuclei with vlba Experiments. v. Multi-Epoch vlba Images journal February 2009
Particle Acceleration in Relativistic Magnetized Collisionless pair Shocks: Dependence of Shock Acceleration on Magnetic Obliquity journal June 2009
THE EVOLUTION OF SWIFT /BAT BLAZARS AND THE ORIGIN OF THE MeV BACKGROUND journal June 2009
Particle acceleration at oblique shock fronts journal August 1989
The synchrotron and cyclo-synchrotron absorption cross-section journal October 1991
Photometric calibration of the Swift ultraviolet/optical telescope: Photometric calibration of the Swift UVOT journal December 2007
The power of blazar jets: The power of blazar jets journal February 2008
Modelling rapid TeV variability of PKS 2155−304 journal October 2008
A unifying view of gamma-ray burst afterglows journal February 2009
GeV gamma-ray attenuation and the high-redshift UV background journal November 2009
Fast TeV variability in blazars: jets in a jet journal May 2009
The Fermi blazars' divide journal June 2009
Electrostatic Potentials in Supernova Remnant Shocks book January 2006
Unfolding of differential energy spectra in the MAGIC experiment
  • Albert, J.; Aliu, E.; Anderhub, H.
  • Nuclear Instruments and Methods in Physics Research Section A: Accelerators, Spectrometers, Detectors and Associated Equipment, Vol. 583, Issue 2-3 https://doi.org/10.1016/j.nima.2007.09.048
journal December 2007
The Discrete Correlation Function: A New Method for Analyzing Unevenly Sampled Variability Data journal January 1989
The physical parameters of Markarian 501 during flaring activity journal December 1999
Comment on the first-order Fermi acceleration at ultra-relativistic shocks journal October 2002
Structured jets in TeV BL Lac objects and radiogalaxies: Implications for the observed properties journal March 2005
Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71: III. Rapid and correlated flux density variability from radio to sub-mm bands journal September 2008
The jet of Markarian 501 from millions of Schwarzschild radii down to a few hundreds journal July 2008
Fifteen years monitoring of extragalactic radio sources at 22, 37 and 87 GHz journal November 1998
Multiwavelength observations of a flare from Markarian 501 conference January 1997
Spectra and linear polarizations of extragalactic variable sources at centimeter wavelengths journal November 1985
Modeling the Effects of Dust on Galactic Spectral Energy Distributions from the Ultraviolet to the Millimeter Band journal December 1998
Variability Pattern and the Spectral Evolution of the BL Lacertae Object PKS 2155−304 journal January 2000
On Pair Content and Variability of Subparsec Jets in Quasars journal May 2000
Detection of Gamma Rays with [ITAL]E[/ITAL] ] 300 GeV from Markarian 501 journal January 1996
Stellar Velocity Dispersion and Black Hole Mass in the Blazar Markarian 501 journal February 2002
Multiwavelength Observations of Strong Flares from the TeV Blazar 1ES 1959+650 journal January 2004
On the Efficiency of Fermi Acceleration at Relativistic Shocks journal July 2006
VHE γ‐Ray Observation of the Crab Nebula and its Pulsar with the MAGIC Telescope journal February 2008
OBSERVATIONS OF THE SHELL-TYPE SUPERNOVA REMNANT CASSIOPEIA A AT TeV ENERGIES WITH VERITAS journal April 2010
The Swift Ultra-Violet/Optical Telescope journal October 2005
The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections journal September 2005
[ITAL]BeppoSAX[/ITAL] Observations of Unprecedented Synchrotron Activity in the BL Lacertae Object Markarian 501 journal January 1998
BVR photometry of comparison stars in selected blazar fields : I. Photometric sequences for 10 BL Lacertae objects journal June 1998
Multiwavelength Observations of Markarian 421 in 2001 March: An Unprecedented View on the X‐Ray/TeV Correlated Variability journal April 2008
On the Momentum Diffusion of Radiating Ultrarelativistic Electrons in a Turbulent Magnetic Field journal July 2008
FERMI LARGE AREA TELESCOPE FIRST SOURCE CATALOG journal May 2010
The burst Alert Telescope (BAT) on the Swift MIDEX mission conference February 2004
The Likelihood Analysis of EGRET Data journal April 1996
Parsec‐Scale Properties of Markarian 501 journal January 2004
Electrostatic Potentials in Supernova Remnant Shocks journal December 2006
The multifrequency emission of Mrk 501: From radio to TeV gamma-rays journal March 2001
VHE Gamma-Ray Observation of the Crab Nebula and its Pulsar with the MAGIC telescope text January 2007
3C454.3 reveals the structure and physics of its 'blazar zone' text January 2007
Synchrotron Self-Compton Analysis of TeV X-ray Selected BL Lacertae Objects text January 2008
The extragalactic optical-infrared background radiations, their time evolution and the cosmic photon-photon opacity text January 2008
The jet of Markarian 501 from millions of Schwarzschild radii down to a few hundreds text January 2008
Modelling rapid TeV variability of PKS 2155-304 text January 2008
Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71, III. Rapid and correlated flux density variability from radio to sub-mm bands text January 2008
Improving the performance of the single-dish Cherenkov telescope MAGIC through the use of signal timing text January 2008
Significant Limb-Brightening in the Inner Parsec of Markarian 501 text January 2008
Constraining Emission Models of Luminous Blazar Sources text January 2009
The Evolution of Swift/BAT blazars and the origin of the MeV background text January 2009
The GASP-WEBT monitoring of 3C 454.3 during the 2008 optical-to-radio and gamma-ray outburst text January 2009
Simultaneous Multiwavelength observation of Mkn 501 in a low state in 2006 text January 2009
The Spectral Energy Distribution of Fermi bright blazars text January 2009
Comment on the first-order Fermi acceleration at ultra-relativistic shocks text January 2001
Energetics of Tev Blazars and Physical Constraints on their Emission Regions text January 2001
Particle acceleration by ultra-relativistic shocks: theory and simulations text January 2001
Stellar Velocity Dispersion and Black Hole Mass in the Blazar Markarian 501 text January 2002
Log-parabolic spectra and particle acceleration in blazars - II: The BeppoSAX wide band X-ray spectra of Mkn 501 text January 2004
The Leiden/Argentine/Bonn (LAB) Survey of Galactic HI: Final data release of the combined LDS and IAR surveys with improved stray-radiation corrections text January 2005
The Burst Alert Telescope (BAT) on the Swift MIDEX Mission text January 2005
The Swift Ultra-Violet/Optical Telescope text January 2005
The Swift X-ray Telescope text January 2005
Temporal Evolution of Pair Attenuation Signatures in Gamma-Ray Burst Spectra text January 2006
Energy spectra of cosmic rays accelerated at ultrarelativistic shock waves text January 1998
The physical parameters of Markarian 501 during flaring activity text January 1999
On Pair Content and Variability of Sub-Parsec Jets in Quasars text January 1999

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The F-GAMMA programme: multi-frequency study of active galactic nuclei in the Fermi era : Programme description and the first 2.5 years of monitoring⋆ journal November 2016
Very high energy outburst of Markarian 501 in May 2009 journal October 2016
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Baryon Loading Efficiency and Particle Acceleration Efficiency of Relativistic Jets: Cases for low Luminosity bl lacs journal August 2016
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Extremely Rapid X-Ray Flares of TeV Blazars in the RXTE Era journal January 2018
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NuSTAR Observations and Multiwavelength Modeling of the High-redshift BL Lacertae Object 4FGL J2146.5-1344 journal January 2020
Strong X-Ray and Multiwavelength Flaring Activity for 1ES 1959+650, 2016 August–2017 November journal September 2018
Limits on the extragalactic background light in the Fermi era journal June 2012
The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies journal April 2015
Multiband optical flux density and polarization microvariability study of optically bright blazars journal December 2019
Discovery of high and very high-energy emission from the BL Lacertae object SHBL J001355.9–185406 text January 2013
Very high energy outburst of Markarian 501 in May 2009 text January 2016
Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009 text January 2017
Multi-Color Optical Monitoring of mrk 501 from 2010 to 2015 journal February 2016
New High- z BL Lacs Using the Photometric Method with Swift and SARA journal May 2018
The Properties of Parsec-scale Blazar Jets journal January 2019
Stable Radio Core of the Blazar Mrk 501 during High-energy Active State in 2012 journal October 2019
MAGIC detection of very high energy γ-ray emission from the low-luminosity blazar 1ES 1741+196 journal February 2017
Fractional variability—a tool to study blazar variability text January 2019
Study of the variable broadband emission of Markarian 501 during the most extreme Swift X-ray activity journal May 2020
Limits on the extragalactic background light in the Fermi era
  • Meyer, Manuel; Raue, Martin; Mazin, Daniel
  • HIGH ENERGY GAMMA-RAY ASTRONOMY: 5th International Meeting on High Energy Gamma-Ray Astronomy, AIP Conference Proceedings https://doi.org/10.1063/1.4772332
conference January 2012
Fermi Large Area Telescope Observations of Markarian 421: The Missing Piece of its Spectral Energy Distribution text January 2011
The extreme HBL behaviour of Markarian 501 during 2012 text January 2018
Fractional Variability—A Tool to Study Blazar Variability text January 2019
Minute-scale Rapid Variability of Mrk 501 by Multi-band Photometric Monitoring from 2010 to 2017 journal June 2019
Discovery of high and very high-energy emission from the BL Lac object SHBL J001355.9-185406 text January 2013
Gamma-rays from Blazars and the Extragalactic Background Light text January 2013
Extreme Blazars Studied with Fermi-LAT and Suzaku: 1ES 0347-121 and Blazar Candidate HESS J1943+213 text January 2014
The Origin of the Extragalactic Gamma-Ray Background and Implications for Dark-Matter Annihilation text January 2015
The 2009 multiwavelength campaign on Mrk 421: Variability and correlation studies text January 2015
The extragalactic background light, the Hubble constant, and anomalies: conclusions from 20 years of TeV gamma-ray observations text January 2015
Baryon Loading Efficiency and Particle Acceleration Efficiency of Relativistic Jets: Cases For Low Luminosity BL Lacs text January 2016
Extremely rapid x-ray flares of tev blazars in the rxte era text January 2017
Multiband optical flux density and polarization microvariability study of optically bright blazars text January 2019
NuSTAR Observations and multi-wavelength modeling of the high-redshift BL Lac Object 4FGL J2146.5-1344 text January 2020

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Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BL LACERTAE OBJECTS
EMISSION
ENERGY SPECTRA
GALAXIES
GAMMA RADIATION
GAMMA SPECTRA
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
RADIATIONS
SPECTRA