Spherical accretion in nearby weakly active galaxies

N. Copernicus Astronomical Center, Bartycka 18, 00-716, Warsaw, Poland e-mail: mmosc@camk.edu.pl

Received: 6 September 2005
Accepted: 15 December 2005

Abstract

We consider the sample of weakly active galaxies situated in the “Local Universe” with inferred accretion efficiencies from 10^-2 to 10^-7. We apply a model of spherically symmetrical Bondi accretion for given parameters (, , ,) taken from observation. We calculate spectra emitted by the gas accreting onto its central objects using a Monte Carlo method including synchrotron and bremsstrahlung photons as seed photons. We then compare our results with observed nuclear X-ray luminosities  (0.3–10 keV) for the sample. A model is also tested for different external medium parameters ( and ) and different free parameters of the model. Our model is able to explain observed nuclear luminosities L_X under an assumption that half of the compression energy is transferred directly to the electrons.