Spitzer Space Telescope - General Observer Proposal #50818


Discovering Compton-thick AGN over the Widest XMM-Newton Field

Principal Investigator: David Alexander
           Institution: Durham University

     Technical Contact: David Alexander, Durham University

Co-Investigators: 
Jonathan Gelbord, Durham University                                   
Martin Ward, Durham University                                        
Andrew Goulding, Durham University                                    

Science Category: AGN/quasars/radio galaxies 
 Observing Modes: IrsStare MipsPhot 
  Hours Approved: 23.2 

Abstract:
Deep X-ray surveys have identified large numbers of AGNs in a relatively
obscuration-independent manner. However, there is considerable evidence that
>50% of luminous AGNs remain undetected, most of which will be heavily obscured
by Compton-thick material. We have used the widest XMM-Newton survey (the
Serendipity Survey) to select AGNs in the SDSS that have luminous [OIII]
emission but are X-ray undetected down to faint limits, implying ~two orders of
magniude of extinction (i.e., likely to be Compton thick). Here we propose for
Spitzer-IRS low-resolution spectroscopy and MIPS~24um and 70um observations of
15 objects to measure the dust-reradiated emission from AGN and star-formation
components, to confirm if they are Compton-thick AGNs. The sample probes regions
of the z-L_AGN plane (z~0.1-0.2; L_X, abs~3x10^41-3x10^43 erg/s) that are not
well sampled by deeper narrow-field X-ray surveys.