TWELVE AND A HALF YEARS OF OBSERVATIONS OF CENTAURUS A WITH THE ROSSI X-RAY TIMING EXPLORER
- Center for Astrophysics and Space Sciences, University of California, San Diego, CA 92093-0424 (United States)
- CSST, University of Maryland Baltimore County, 1000 Hilltop Circle, Baltimore, MD 21250 (United States)
- Dr. Remeis Sternwarte and ECAP, Sternwartstr. 7, 96049 Bamberg (Germany)
The Rossi X-ray Timing Explorer (RXTE) has observed the nearest radio galaxy, Centaurus A (Cen A), in 13 intervals from 1996 August to 2009 February over the 3-200 keV band. Spectra accumulated over the 13 intervals were well described with an absorbed power law and an iron line. Cutoff power laws and Compton reflection from cold matter did not provide a better description. For the 2009 January observation, we set a lower limit on the cutoff energy at over 2 MeV. The power spectral density function was generated from RXTE/All Sky Monitor and Proportional Counter Array data as well as an XMM-Newton long look, and clear evidence for a break at 18{sup +18}{sub -7} days (68% conf.) was seen. Given Cen A's high black hole mass and very low value of L{sub X}/L{sub Edd}, the break was a factor of 17{sup +36}{sub -13} times higher than the break frequency predicted by the McHardy et al. relation, which was empirically derived for a sample of objects, which are radio-quiet and accreting at relatively high values of L{sub bol}/L{sub Edd}. We have interpreted our observations in the context of a clumpy molecular torus. The variability characteristics and the broadband spectral energy distribution, when compared to Seyferts, imply that the bright hard X-ray continuum emission may originate at the base of the jet, yet from behind the absorbing line-of-sight material, in contrast to what is commonly observed from blazars.
- OSTI ID:
- 21576804
- Journal Information:
- Astrophysical Journal, Vol. 733, Issue 1; Other Information: DOI: 10.1088/0004-637X/733/1/23; ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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