The structure of AGNs from X-ray absorption variability
Abstract
We present new evidence of X-ray absorption variability on time scales from a few hours to a few days for several nearby bright AGNs. The observed N_H variations imply that the X-ray absorber is made of clouds eclipsing the X-ray source with velocities in excess of 10^3 km/s, and densities, sizes and distances from the central black hole typical of BLR clouds. We conclude that the variable X-ray absorption is due to the same clouds emitting the broad emission lines in the optical/UV. We then concentrate on the two highest signal-to-noise spectra of eclipses, discovered in two long observations of NGC 1365 and Mrk 766, and we show that the obscuring clouds have a cometary shape, with a high density head followed by a tail with decreasing N_H. Our results show that X-ray time resolved spectroscopy can be a powerful way to directly measure the physical and geometrical properties of BLR clouds.
Cite
@article{arxiv.0912.2118,
title = {The structure of AGNs from X-ray absorption variability},
author = {Guido Risaliti},
journal= {arXiv preprint arXiv:0912.2118},
year = {2015}
}
Comments
8 Pages, 5 figures. Proceedings of IAU Symposium 267 "Co-Evolution of Central Black Holes and Galaxies"