A Composite Seyfert 2 X-ray Spectrum: Implications for the Origin of the Cosmic X-ray Background
Abstract
We present a composite 1-10 keV Seyfert 2 X-ray spectrum, derived from ASCA observations of a distance-limited sample of nearby galaxies. All 29 observed objects were detected. Above ~3 keV, the composite spectrum is inverted, confirming that Seyfert 2 galaxies as a class have the spectral properties necessary to explain the flat shape of the cosmic X-ray background spectrum. Integrating the composite spectrum over redshift, we find that the total emission from Seyfert 2 galaxies, combined with the expected contribution from unabsorbed type 1 objects, provides an excellent match to the spectrum and intensity of the hard X-ray background. The principal uncertainty in this procedure is the cosmic evolution of the Seyfert 2 X-ray luminosity function. Separate composite spectra for objects in our sample with and without polarized broad optical emission lines are also presented.
Cite
@article{arxiv.astro-ph/0106519,
title = {A Composite Seyfert 2 X-ray Spectrum: Implications for the Origin of the Cosmic X-ray Background},
author = {Edward C. Moran and Laura E. Kay and Marc Davis and Alexei V. Filippenko and Aaron J. Barth},
journal= {arXiv preprint arXiv:astro-ph/0106519},
year = {2009}
}
Comments
11 pages (AASTeX), including 3 figures. Accepted for publication in ApJ Letters