Research News:

Tim O'Hara has just published a very interesting study of the evolution of galaxy cluster structure between 0.2<z<1.3. The data indicate that clusters do not evolve in a manner consistent with the self-similar model. Moreover, three X-ray scaling relation (luminsity-temperature, ICM mass-temperature and isophotal size-temperature) evolve in a manner that can be explained by a graduate change in the ICM mass fraction with redshift. Follow the publications link for more details.

We are embarking on the 3rd year of observing in the Blanco Cosmology Survey. This is a 45 night program to image 100 deg^2 in griz to sufficient depth to measure cluster photometric redshifts to z~1. In addition, we have recently been granted a 6 deg^2 XMM survey (X-BCS) of a portion of the BCS and a 12 deg^2 Spitzer IRAC survey (S-BCS) of an overlapping region. Currently the SPT is scanning a ~50 deg^2 region where BCS optical data already exist. Reductions are proceding well with the BCS data, with data from the first two seasons reduced and released to the collaboration on June 1, 2007. Science analyses are underway! An NSF proposal to fund my group's involvement in BCS was just funded.

The Dark Energy Survey (DES) has recently been funded by both NSF and DOE. The DOE Critical Decision 1 has been granted for the camera, and NSF funds are now flowing to my DES data management team at U Illinois. We are headed toward a Critical Decision 2 review at the end of January, 2008.

Scientific analysis of the evolution of X-ray structure in a large sample of galaxy clusters is almost complete with submission of publication about to occur. Indications from O'Hara's and my analysis of a large Chandra sample are that cluster do not evolve consistently with self-similar evolution, evolving more slowly in properties such as intracluster medium mass and X-ray luminosity than would be expected in the self-similar evolution model. These cluster do show clear evolution, though, with the data also ruling out a no-evolution model. The cluster structural evolution can be explained by a gradual evolution of the intracluster medium mass fraction in clusters between z=0.2 and 1.2.