Journal Article

A serendipitous <i>XMM</i> survey of the SDSS: the evolution of the colour–magnitude diagram of X-ray AGN from <i>z</i>= 0.8 to 0.1

Antonis Georgakakis and K. Nandra

in Monthly Notices of the Royal Astronomical Society

Published on behalf of The Royal Astronomical Society

Volume 414, issue 2, pages 992-1010
Published in print June 2011 | ISSN: 0035-8711
Published online June 2011 | e-ISSN: 1365-2966 | DOI:
A serendipitous XMM survey of the SDSS: the evolution of the colour–magnitude diagram of X-ray AGN from z= 0.8 to 0.1

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A new serendipitous XMM survey in the area of the Sloan Digital Sky Survey is described (XMM/SDSS), which includes features such as merging of overlapping fields to increase the sensitivity to faint sources, use of a new parametrization of the XMM point spread function for the source detection and photometry and an accurate estimation of the survey sensitivity. About 40 000 X-ray point sources are detected over a total area of 122 deg2. A subsample of 209 sources detected in the 2–8 keV spectral band with SDSS spectroscopic redshifts in the range of 0.03 < z < 0.2, optical magnitudes r < 17.77 mag and (erg s−1) is selected to explore their distribution on the colour–magnitude diagram. This is compared with the colour–magnitude diagram of X-ray AGN in the AEGIS field at z≈ 0.8. We find no evidence for evolution of the rest-frame colours of X-ray AGN hosts from z= 0.8 to 0.1. This suggests that the dominant accretion mode of the AGN population, which is expected to imprint on the properties of their host galaxies, does not change since z= 0.8. This argues against scenarios that attribute the rapid decline of the accretion power of the Universe with time (1 dex since z= 0.8) to changes in the AGN fuelling/triggering mode.

Keywords: methods: data analysis; galaxies: active; galaxies: Seyfert; X-rays: diffuse background; astronomical data bases: surveys

Journal Article.  16098 words.  Illustrated.

Subjects: Astronomy and Astrophysics

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