An HST/ACS Treasury Survey of the Coma Cluster

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Ground-based image roughly corresponding to the rectangular tiled area, referred to as the `core region' of the Coma galaxy cluster, shown in the two images at the bottom of this page. (Credit & Copyright: Jim Misti.)

The Hubble Space Telescope's survey of the Coma galaxy cluster is one of only two prestigious Cycle 15 (2006/7) Treasury Programs. It involves more than 30 research astronomers, including those at Swinburne University of Technology, from nine nations. The survey goal is to image 740 square arcmin of sky using Hubble's Advanced Camera for Surveys (ACS) F475W (blue) and F814W (red) filters. The selected areas cover both the core (see above) and infall region (see below) of this rich galaxy cluster.

The Coma cluster provides the opportunity to study galaxies in an environment different to that in any previous large HST programme. The Coma core is the densest galaxy environment in the local universe. As such, it provides a key local, high-density benchmark for comparison to surveys of less dense and relaxed environments (e.g., the Virgo, Fornax and Perseus galaxy clusters), high-redshift HST cluster surveys and field surveys such as HUDF, GOODS and GEMS. Key science goals of this project are:

The Coma survey was originally scheduled for completion in early 2008, but the failure of the ACS on January 27, 2007 means that it will not now be complete until after HST Servicing Mission 4 in early 2009. The HST survey is paused, with 28% of its data in-hand. However the wider project will continue to gather data throughout this period. Members of the collaboration have either brought in, or subsequently obtained time for, observations of the Coma cluster with the VLA, Spitzer/IRAC, Galex, XMM-Newton, Chandra, Keck/Deimos, MMT/Hectospec, CFHT/WIRCAM and Subaru/Suprime-Cam.

Left: Overlay on a DSS image of the ACS fields from the complete survey. Right: Overlay on a DSS image of the ACS fields observed before the ACS failure on the 27th of January, 2007. (Credit: David Carter.)