On the origin of the X-rays and the nature of accretion in NGC 4261

M. Gliozzi, R. M. Sambruna, W. N. Brandt
2003 Astronomy and Astrophysics  
We report on the X-ray properties of the radio galaxy NGC 4261, combining information from the XMM, Chandra, and SAX satellites. Goals of this study are to investigate the origin of the X-rays from this low-power radio galaxy and the nature of the accretion process onto the central black hole. The X-ray spectrum of the nuclear source extending up to 100--150 keV is well described by a partially covered (covering factor > 0.8) power law with a photon index 1̃.5 absorbed by a column density 5e22
more » ... m^-2. The X-ray luminosity associated with the non-thermal component is 5e41 erg/s. The nuclear source is embedded in a diffuse hot gas (kT 0.6 keV), whose density profile implies a Bondi accretion rate of 4.5e-2 solar masses/year. For the first time rapid X-ray variability is detected in a low-power radio galaxy at more than 99 level. The observed X-ray spectral and variability properties indicate the accretion flow as the most likely origin of the bulk X-ray continuum.This conclusion is strengthened by energetic considerations based on a comparison between the X-ray luminosity and the kinetic power of the jet, whichalso suggest that the Bondi accretion rate overestimates the actual accretion rate onto the black hole.
doi:10.1051/0004-6361:20031050 fatcat:nxqm64tbtfgxhpetda65rnitnu