X-ray Variability and Spectral Scaling: A measure of BLR sizes in AGN
Abstract
We developed a new method of determination of the size of the broad emission-line region (BLR) in active galactic nuclei. This method relates the radius of the broad-line region of AGN to the soft X-ray luminosity and spectral index: sources with comparable luminosity but a steeper (or softer) spectrum have more ionizing photons (hence a larger ionizing power), and will produce the emission line region at a larger distance from the central source. Comparing the BLR distances calculated from our model to the BLR distances in 8 AGN and quasars determined by reverberation mapping shows that our scaling law improves over the simple $r\sim L^{1/2}$ empirical relation, in particular for the objects with steep spectra (NGC 4151 and NGC 5548). We present also a third method of estimating the BLR distance - based on the emission-line width and the central mass estimated from X-ray variability.
- Publication:
-
Astronomical Time Series
- Pub Date:
- 1997
- DOI:
- 10.1007/978-94-015-8941-3_37
- arXiv:
- arXiv:astro-ph/9703198
- Bibcode:
- 1997ASSL..218..255W
- Keywords:
-
- Astrophysics
- E-Print:
- 4 page latex file, 2 figs. Complete uuencoded compressed PS file is also available at ftp://saba.fiz.huji.ac.il/~pub/wandel/blrx_ts.uu or at http://shum.cc.huji.ac.il/~amri/papers/blrx_ts(tex,ps) to appear in Proc. of Astronomical Time Series