Abstract
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.
| Original language | English |
|---|---|
| Pages (from-to) | 673-677 |
| Number of pages | 5 |
| Journal | Astrophysical Journal |
| Volume | 649 |
| Issue number | 2 I |
| DOIs | |
| State | Published - 1 Oct 2006 |
Keywords
- Galaxies: clusters: general
- Galaxies: clusters: individual (A2163)
- Galaxies: magnetic fields
- Radiation mechanisms: nonthermal