Supervisor : Prof Mike Watson (mgw@star.le.ac.uk)

Details of Project

Recent studies of the extragalactic X-ray source population, in particular active galaxies powered by a central supermassive black hole (SMBH), have demonstrated that a significant fraction of the accretion power in the Universe must occur in obscured objects. 

Collage of Thumbnail SDSS Optical Images of 50 AGN Selected from the 2XMMi Catalogue. In the left panel the objects are type 1 AGN where the nucleus dominates, whilst in the right panel objects the AGN nucleus is obscured optically, with the AGN nature only revealed by their strong X-ray emission.

These studies have also started to reveal the intimate links between the central engines in these objects and their host galaxies. X-ray studies provide the only direct view of the central engines in these objects and one of the best ways of directly determining the properties of their SMBHs. Detailed X-ray studies of AGN have, however, focused on bright and nearby objects. Studies of fainter objects (eg. at higher redshifts) have been limited by sample statistics and poor signal-to-noise data. Extending these studies using large, higher quality samples is needed to understand the whole population. X-ray surveys offer the key to this, providing the data needed to determine the Universe's accretion history. This is a topic of wide importance, due to the strong connections that we know exist between the formation and evolution of super-massive black holes (SMBH) in galactic nuclei and the bulges of their host galaxies.

Sources of Data

This project can be pursued with two major observational resources:

• The 2XMM catalogue(s) which provide unrivalled wide-area X-ray survey data to explore the properties of the AGN population. The most recent release of the catalogue – 2XMMi-DR3- contains 350,000 X-ray sources drawn from observations covering a sky area ~500 sq.deg. 
  The XMM catalogues offer sample sizes 20-100 times larger than have previously been available which, coupled with other large area multi-wavelength datasets, such as SDSS, UKIDSS and Vista, represent an unique resource for the characterisation of AGN beyond the local Universe.
• The Subaru-XMM Deep Field (SXDF), a 1 sq.deg. deep survey region with superb multi-wavelength coverage from XMM-Newton, Subaru SuprimeCam, UKIDSS UDS, Spitzer IRAC & MIPS, VLA, Scuba and Galex. 

Background Reading

The 2XMM catalogue pages can be found here