2006/06/05 by Yoel Rephaeli, D. E. Gruber, Duane Gruber +1
Physics and Astronomy · #Astrophysical Phenomena and Observations #Astrophysics #Astrophysics and Cosmic Phenomena #Cluster (spacecraft) #Compton scattering #Cosmic microwave background #Electron #Electron temperature #Flux (metallurgy) #Gamma-ray bursts and supernovae #Halo #Magnetic field #Nuclear physics #Optics #Physics #astro-ph
paper · pdf · doi:10.1086/506310
published as Astrophys.J.649:673-677,2006 · 10 pages, 1 figure; accepted for publication in ApJ
arxiv created 2006/06/05 · openalex publication_date 2006/09/27 · arxiv updated 2009/12/01 · openalex created_date 2016/06/24 · openalex updated_date 2026/08/05
A2163 was observed by the RXTE satellite for ~530 ks during a 6 month period, starting in 2004 August. The cluster primary emission is from very hot intracluster gas with kT ~ 15 keV, but this component does not by itself provide the best-fitting model. A secondary emission component is quite clearly needed, and while this could also be thermal at a temperature significantly lower than kT ~ 15 keV, the best fit (to the combined PCA and HEXTE data sets) is obtained with a power-law secondary spectral component. The deduced parameters of the nonthermal (NT) emission imply a significant fractional flux amounting to ~25% of the integrated 3-50 keV emission. NT emission is expected, given the intense level of radio emission, most prominently from a large extended ("halo") central region of the cluster. Interpreting the deduced NT emission as Compton scattering of the radio-emitting relativistic electrons by the CMB, we estimate the volume-averaged value of the magnetic field in the extended radio region to be B ~ 0.4 ± 0.2 μG.