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Title: THE LACK OF DIFFUSE, NON-THERMAL HARD X-RAY EMISSION IN THE COMA CLUSTER: THE SWIFT BURST ALERT TELESCOPE'S EYE VIEW

Abstract

The Coma Cluster of galaxies hosts the brightest radio halo known and has therefore been the target of numerous searches for associated inverse Compton (IC) emission, particularly at hard X-ray energies where the IC signal must eventually dominate over thermal emission. The most recent search with the Suzaku Hard X-ray Detector failed to confirm previous IC detections with RXTE and BeppoSAX, instead setting an upper limit 2.5 times below their non-thermal flux. However, this discrepancy can be resolved if the IC emission is very extended, beyond the scale of the cluster radio halo. Using reconstructed sky images from the 58-month Swift Burst Alert Telescope (BAT) all-sky survey, the feasibility of such a solution is investigated. Building on Renaud et al., we test and implement a method for extracting the fluxes of extended sources, assuming specified spatial distributions. BAT spectra are jointly fit with an XMM-Newton EPIC-pn spectrum derived from mosaic observations. We find no evidence for large-scale IC emission at the level expected from the previously detected non-thermal fluxes. For all non-thermal spatial distributions considered, which span the gamut of physically reasonable IC models, we determine upper limits for which the largest (most conservative) limit is {approx}<4.2 x 10{sup -12}more » erg s{sup -1} cm{sup -2} (20-80 keV), which corresponds to a lower limit on the magnetic field B > 0.2 {mu} G. A nominal flux upper limit of <2.7 x 10{sup -12} erg s{sup -1} cm{sup -2}, with corresponding B > 0.25 {mu} G, is derived for the most probable IC distribution given the size of the radio halo and likely magnetic field radial profile.« less

Authors:
; ; ;  [1];  [2];  [3];  [4]
  1. Astrophysics Science Division, Laboratory for High Energy Astrophysics, Code 662, NASA/Goddard Space Flight Center, Greenbelt, MD 20771 (United States)
  2. Department of Astronomy, University of Virginia, 530 McCormick Road Charlottesville, VA 22904 (United States)
  3. Max-Planck-Institut fuer Extraterrestrische Physik, Giessenbachstr., 85748 Garching (Germany)
  4. Department of Astronomy, University of Maryland, College Park, MD 20742 (United States)
Publication Date:
OSTI Identifier:
21567515
Resource Type:
Journal Article
Journal Name:
Astrophysical Journal
Additional Journal Information:
Journal Volume: 727; Journal Issue: 2; Other Information: DOI: 10.1088/0004-637X/727/2/119; Journal ID: ISSN 0004-637X
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; EMISSION; GALAXY CLUSTERS; HARD X RADIATION; MAGNETIC FIELDS; X-RAY GALAXIES; COSMIC RAY SOURCES; COSMIC X-RAY SOURCES; ELECTROMAGNETIC RADIATION; GALAXIES; IONIZING RADIATIONS; RADIATIONS; X RADIATION

Citation Formats

Wik, Daniel R, Baumgartner, Wayne H, Okajima, Takashi, Tueller, Jack, Sarazin, Craig L, Finoguenov, Alexis, Mushotzky, Richard F, and Clarke, Tracy E., E-mail: daniel.r.wik@nasa.gov. THE LACK OF DIFFUSE, NON-THERMAL HARD X-RAY EMISSION IN THE COMA CLUSTER: THE SWIFT BURST ALERT TELESCOPE'S EYE VIEW. United States: N. p., 2011. Web. doi:10.1088/0004-637X/727/2/119.
Wik, Daniel R, Baumgartner, Wayne H, Okajima, Takashi, Tueller, Jack, Sarazin, Craig L, Finoguenov, Alexis, Mushotzky, Richard F, & Clarke, Tracy E., E-mail: daniel.r.wik@nasa.gov. THE LACK OF DIFFUSE, NON-THERMAL HARD X-RAY EMISSION IN THE COMA CLUSTER: THE SWIFT BURST ALERT TELESCOPE'S EYE VIEW. United States. https://doi.org/10.1088/0004-637X/727/2/119
Wik, Daniel R, Baumgartner, Wayne H, Okajima, Takashi, Tueller, Jack, Sarazin, Craig L, Finoguenov, Alexis, Mushotzky, Richard F, and Clarke, Tracy E., E-mail: daniel.r.wik@nasa.gov. 2011. "THE LACK OF DIFFUSE, NON-THERMAL HARD X-RAY EMISSION IN THE COMA CLUSTER: THE SWIFT BURST ALERT TELESCOPE'S EYE VIEW". United States. https://doi.org/10.1088/0004-637X/727/2/119.
@article{osti_21567515,
title = {THE LACK OF DIFFUSE, NON-THERMAL HARD X-RAY EMISSION IN THE COMA CLUSTER: THE SWIFT BURST ALERT TELESCOPE'S EYE VIEW},
author = {Wik, Daniel R and Baumgartner, Wayne H and Okajima, Takashi and Tueller, Jack and Sarazin, Craig L and Finoguenov, Alexis and Mushotzky, Richard F and Clarke, Tracy E., E-mail: daniel.r.wik@nasa.gov},
abstractNote = {The Coma Cluster of galaxies hosts the brightest radio halo known and has therefore been the target of numerous searches for associated inverse Compton (IC) emission, particularly at hard X-ray energies where the IC signal must eventually dominate over thermal emission. The most recent search with the Suzaku Hard X-ray Detector failed to confirm previous IC detections with RXTE and BeppoSAX, instead setting an upper limit 2.5 times below their non-thermal flux. However, this discrepancy can be resolved if the IC emission is very extended, beyond the scale of the cluster radio halo. Using reconstructed sky images from the 58-month Swift Burst Alert Telescope (BAT) all-sky survey, the feasibility of such a solution is investigated. Building on Renaud et al., we test and implement a method for extracting the fluxes of extended sources, assuming specified spatial distributions. BAT spectra are jointly fit with an XMM-Newton EPIC-pn spectrum derived from mosaic observations. We find no evidence for large-scale IC emission at the level expected from the previously detected non-thermal fluxes. For all non-thermal spatial distributions considered, which span the gamut of physically reasonable IC models, we determine upper limits for which the largest (most conservative) limit is {approx}<4.2 x 10{sup -12} erg s{sup -1} cm{sup -2} (20-80 keV), which corresponds to a lower limit on the magnetic field B > 0.2 {mu} G. A nominal flux upper limit of <2.7 x 10{sup -12} erg s{sup -1} cm{sup -2}, with corresponding B > 0.25 {mu} G, is derived for the most probable IC distribution given the size of the radio halo and likely magnetic field radial profile.},
doi = {10.1088/0004-637X/727/2/119},
url = {https://www.osti.gov/biblio/21567515}, journal = {Astrophysical Journal},
issn = {0004-637X},
number = 2,
volume = 727,
place = {United States},
year = {Tue Feb 01 00:00:00 EST 2011},
month = {Tue Feb 01 00:00:00 EST 2011}
}