TY - JOUR
T1 - Galaxy clusters in the swift/burst alert telescope era
T2 - Hard X-rays in the intracluster medium
AU - Ajello, M.
AU - Rebusco, P.
AU - Cappelluti, N.
AU - Reimer, O.
AU - Böhringer, H.
AU - Greiner, J.
AU - Gehrels, N.
AU - Tueller, J.
AU - Moretti, A.
PY - 2009/1/1
Y1 - 2009/1/1
N2 - We report the detection of 10 clusters of galaxies in the ongoing Swift/Burst Alert Telescope (BAT) all-sky survey. This sample, which mostly comprises merging clusters, was serendipitously detected in the 15-55 keV band. We use the BAT sample to investigate the presence of excess hard X-rays above the thermal emission. The BAT clusters do not show significant (e.g., ≥2σ) nonthermal hard X-ray emission. The only exception is represented by Perseus whose high-energy emission is likely due to NGC 1275. Using XMM-Newton, Swift/XRT, Chandra and BAT data, we are able to produce upper limits of the inverse Compton (IC) emission mechanism which are in disagreement with most of the previously-claimed hard X-ray excesses. The coupling of the X-ray upper limits of the IC mechanism to radio data shows that, in some clusters, the magnetic field might be larger than 0.5 μG. We also derive the first log N-log S and luminosity function distributions of galaxy clusters above 15 keV.
AB - We report the detection of 10 clusters of galaxies in the ongoing Swift/Burst Alert Telescope (BAT) all-sky survey. This sample, which mostly comprises merging clusters, was serendipitously detected in the 15-55 keV band. We use the BAT sample to investigate the presence of excess hard X-rays above the thermal emission. The BAT clusters do not show significant (e.g., ≥2σ) nonthermal hard X-ray emission. The only exception is represented by Perseus whose high-energy emission is likely due to NGC 1275. Using XMM-Newton, Swift/XRT, Chandra and BAT data, we are able to produce upper limits of the inverse Compton (IC) emission mechanism which are in disagreement with most of the previously-claimed hard X-ray excesses. The coupling of the X-ray upper limits of the IC mechanism to radio data shows that, in some clusters, the magnetic field might be larger than 0.5 μG. We also derive the first log N-log S and luminosity function distributions of galaxy clusters above 15 keV.
KW - Acceleration of particles
KW - Galaxies: clusters: general
KW - Magnetic fields
KW - Radiation mechanisms: non-thermal
KW - X-rays: general
UR - http://www.scopus.com/inward/record.url?scp=65549145612&partnerID=8YFLogxK
UR - http://www.scopus.com/inward/citedby.url?scp=65549145612&partnerID=8YFLogxK
U2 - 10.1088/0004-637X/690/1/367
DO - 10.1088/0004-637X/690/1/367
M3 - Article
AN - SCOPUS:65549145612
VL - 690
SP - 367
EP - 388
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
ER -