Tracing the Jet Contribution to the Mid-IR over the 2005 Outburst of GRO J1655–40 via Broadband Spectral Modeling
The Astrophysical Journal American Astronomical Society 670:1 (2007) 610-623
The High-Energy Emission of GRO J1655–40 As Revealed with INTEGRAL Spectroscopy of the 2005 Outburst
The Astrophysical Journal American Astronomical Society 669:1 (2007) 534-545
Low accretion rates at the AGN cosmic downsizing epoch
ArXiv 0709.0786 (2007)
Abstract:
Context: X-ray surveys of Active Galactic Nuclei (AGN) indicate `cosmic downsizing', with the comoving number density of high-luminosity objects peaking at higher redshifts (z about 2) than low-luminosity AGN (z<1). Aims: We test whether downsizing is caused by activity shifting towards low-mass black holes accreting at near-Eddington rates, or by a change in the average rate of accretion onto supermassive black holes. We estimate the black hole masses and Eddington ratios of an X-ray selected sample of AGN in the Chandra Deep Field South at z<1, probing the epoch where AGN cosmic downsizing has been reported. Methods: Black hole masses are estimated both from host galaxy stellar masses, which are estimated from fitting to published optical and near-infrared photometry, and from near-infrared luminosities, applying established correlations between black hole mass and host galaxy properties. Both methods give consistent results. Comparison and calibration of possible redshift-dependent effects is also made using published faint host galaxy velocity dispersion measurements. Results: The Eddington ratios in our sample span the range 10^{-5} to 1, with median log(L_bol/L_Edd)=-2.87, and with typical black hole masses about 10^{8} solar masses. The broad distribution of Eddington ratios is consistent with that expected for AGN samples at low and moderate luminosity. We find no evidence that the CDF-S AGN population is dominated by low-mass black holes accreting at near-Eddington ratios and the results suggest that diminishing accretion rates onto average-sized black holes are responsible for the reported AGN downsizing at redshifts below unity.The variable radio counterpart and possible large-scale jet of the new Z source XTE J1701−462
Monthly Notices of the Royal Astronomical Society: Letters Oxford University Press (OUP) 380:1 (2007) l25-l29
A link between radio loudness and X-ray/optical properties of AGN
PoSMQW 6 (2007) 026-026