A new population of soft X-ray weak quasars
Abstract
Quasars selected in optical surveys by means of their blue or UV excess are known to be strong emitters in the X-rays, except for Broad Absorption Line (BAL) objects. In this paper we study the X-ray emission of quasars selected through their emission line spectrum rather than their blue excess. X-ray data are obtained by cross-correlating two optical samples (the Hamburg Survey Catalogue and the Palomar Transit Catalogue) with the WGA catalogue of ROSAT observations. We find that a significant fraction of objects are strongly underluminous in the X-rays. We discuss the physical nature of these sources and we propose an interpretation for their optical and X-ray properties based on a dust-poor and gas-rich absorber. Our results suggest the existence of a population of AGNs having a type 1 optical spectrum and a type 2 X-ray emission
Keywords
Cite
@article{arxiv.astro-ph/0102427,
title = {A new population of soft X-ray weak quasars},
author = {G. Risaliti and A. Marconi and R. Maiolino and M. Salvati and P. Severgnini},
journal= {arXiv preprint arXiv:astro-ph/0102427},
year = {2009}
}
Comments
8 pages, 8 figures, accepted for publication by Astronomy & Astrophysics