Issue |
A&A
Volume 408, Number 3, September IV 2003
|
|
---|---|---|
Page(s) | 949 - 959 | |
Section | Extragalactic astronomy | |
DOI | https://doi.org/10.1051/0004-6361:20031050 | |
Published online | 17 November 2003 |
On the origin of the X-rays and the nature of accretion in NGC 4261
1
George Mason University, Dept. of Physics & Astronomy & School of Computational Sciences, 4400 University Drive, MS 3F3, Fairfax, VA 22030, USA
2
The Pennsylvania State University, Department of Astronomy & Astrophysics, 525 Davey Lab, University Park, PA 16802, USA
Corresponding author: M. Gliozzi, mario@physics.gmu.edu
Received:
11
April
2003
Accepted:
7
July
2003
We report on the X-ray properties of the radio galaxy
NGC 4261, combining information from the XMM-Newton, Chandra, and
BeppoSAX 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 absorbed by a column density
. The X-ray luminosity
associated with the non-thermal component is
.
The nuclear source is embedded in a diffuse hot gas (
keV), whose
density profile implies a Bondi accretion rate of
. For the first time rapid X-ray variability is detected in a
low-power radio galaxy at more than 99% confidence 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, which
also suggest that the Bondi accretion rate overestimates the actual accretion rate onto
the black hole.
Key words: galaxies: active / galaxies: nuclei / X-rays: galaxies
© ESO, 2003
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