• X-ray galaxy cluster surveys
• The cluster X-ray luminosity and X-ray temperature functions and their evolution
• Cluster mass measurements, dark matter
• Cosmology
• Large-scale structure / large-scale flows in the local universe
• Galaxy evolution in low- and high-density environments
• Weak and strong gravitational lensing

My research pages are under construction (no, seriously!) - please check back in a few days (um, weeks?) ...

Systematic searches for clusters of galaxies have traditionally been conducted at optical wavelengths, the main selection criterion being the apparent number density of galaxies as seen in projection on the sky. While some of the resulting optical catalogues still constitute the largest compilations of clusters of galaxies in existence, the biases inherent to the optical selection process (most importantly projection effects) are difficult to correct for in statistical studies of cluster properties.

X-ray selection overcomes most of the optical biases as the X-ray emission is an immediate indicator of the presence of gravitationally bound and heated gas. X-ray observations of galaxy clusters thus allow the compilation of cluster samples that are almost unaffected by projection effects.

A new era for the compilation of large-area, X-ray selected cluster samples began in 1990 with the launch of the ROSAT satellite. In 1990-1991 ROSAT completed the first all-sky survey ever conducted with an imaging X-ray telescope, before turning to pointed observations of selected individual targets for the remainder of its 9-year mission. The resulting databases are gold mines for the compilation of large X-ray selected cluster samples.

With the exception of the EMSS, all of the above cluster surveys are based on ROSAT data.

I am involved in a number of X-ray cluster surveys, some of which are not accessible through the above clickable map - so here is the complete list of `my' cluster surveys:

• XBACs (the X-ray Brightest Abell Clusters)
• BCS (the ROSAT Brightest Cluster Sample
• WARPS (the Wide Angle ROSAT Pointed Survey)
• CIZA (Clusters In the Zone of Avoidance)
• MACS (the MAssive Cluster Survey)