The Spitzer/Herschel Active Galaxies Survey

Introduction

We have selected 170 AGN comprising matched samples of radio-quiet and radio-loud QSOs and radio galaxies. The AGN, all at z=1, span a factor of 100 in optical luminosity allowing us to study a wide range of black hole activity at a single cosmologically important epoch devoid of concerns about redshift-luminosity degeneracy. Complete datasets are in-hand from Herschel (PACS/SPIRE - PI Stevens (Herts)), Spitzer (IRAC/MIPS- PI Jarvis (Oxford)) while we have data from XMM-Newton and Swift (PI Page (MSSL)) for the radio quiet objects (PI Page (MSSL)) and now for most of the radio-loud objects as well (PI Hardcastle (Herts)). Additional optical data are available from SDSS and from the XMM Optical Monitor (OM). The major goals of the survey are split into 3 themes:

Images

One of our fields centred on a QSO at z=1 showing evidence for a surrounding cluster. Colour scale shows the IRAC 3.6 micron image, the contours are Herschel SPIRE data at 250 microns, and the image is about 4.5 x 4.5 arcmin.

Results

Overdensity

Over-density of galaxies at 3.6 microns relative to the background calculated in annuli centred on the AGN. We find evidence for larger over-densities around the radio-loud AGN possibly indicating that the dense environment is enhancing the radio luminosity. Alternatively the effect might be caused by an increased merger rate in dense environments which leads to higher black hole spin and thus higher radio luminosity (from Falder et al. 2010, MNRAS, 405, 347).