Spectral Energy Distributions of Type 1 AGN in XMM-COSMOS Survey II - Shape Evolution

TL;DR

This study analyzes the spectral energy distributions of 407 X-ray-selected type 1 AGN in the COSMOS survey, finding no significant evolution or dependence on key parameters, and comparing them with classical SED templates.

Contribution

It provides a comprehensive analysis of SED shape evolution in a large AGN sample, revealing stability across various physical properties and expanding understanding of AGN emission characteristics.

Findings

No significant SED shape evolution with redshift, luminosity, black hole mass, or Eddington ratio.

SED dispersion is larger than in previous templates, possibly due to selection effects.

SED shapes are consistent with classical templates across the studied parameters.

Abstract

The mid-infrared to ultraviolet (0.1 -- 10 $\mu m$) spectral energy distribution (SED) shapes of 407 X-ray-selected radio-quiet type 1 AGN in the wide-field ``Cosmic Evolution Survey" (COSMOS) have been studied for signs of evolution. For a sub-sample of 200 radio-quiet quasars with black hole mass estimates and host galaxy corrections, we studied their mean SEDs as a function of a broad range of redshift, bolometric luminosity, black hole mass and Eddington ratio, and compared them with the Elvis et al. (1994, E94) type 1 AGN mean SED. We found that the mean SEDs in each bin are closely similar to each other, showing no statistical significant evidence of dependence on any of the analyzed parameters. We also measured the SED dispersion as a function of these four parameters, and found no significant dependencies. The dispersion of the XMM-COSMOS SEDs is generally larger than E94 SED dispersion in the ultraviolet, which might be due to the broader ``window function'' for COSMOS quasars, and their X-ray based selection.