The Hubble Space Telescope Treasury Survey
of the Coma Cluster of Galaxies
The heart of the Coma Cluster Treasury Survey is a Hubble Space Telescope (HST) / Advanced Camera for Surveys (ACS) Treasury Program that was designed to survey both the core and an infall region of the richest local cluster of galaxies: the Coma cluster. The observations contain thousands of galaxies down to apparent magnitudes g=27.5 and I=26.6 mag. In addition, numerous supporting ground-based and space-based observing campaigns are being undertaken at other wavelengths. This shall result in a large, multi-wavelength, public database of calibrated images and derived catalogs.
The main scientific objectives of the HST/ACS Treasury Program are:
- To determine the relative abundances of bright and faint galaxies, down to MV = -9 mag.
- To study the "globular star clusters" which are associated with bright and faint galaxies, and learn what they can tell us about galaxy evolution.
- To study the structure of dwarf galaxies, including ultra compact dwarf galaxies, establish their "scaling laws", and compare these with formation models.
- To study the stellar populations from both global colours and radial colour gradients, and how the internal chemical evolution of galaxies is affected by interactions with the cluster environment.
- To determine the effect of the cluster environment upon the morphological features such as disks, bulges, bars and spiral arms, by comparing these structures in the Coma galaxy sample with field galaxy samples.
- To study the nuclear structure of galaxies, including black holes and nuclear star clusters.
- To investigate the nature of "E+A" galaxies.
The Coma cluster provides an opportunity to study galaxies in an environment different to that in any previous large HST program. This is the first such survey of a nearby rich cluster. While the core of the Coma cluster is the densest galaxy environment in the local universe, the cluster as a whole harbors regions of widely varying galaxy densities. As such it allows one to study the role of environment on galaxy formation and evolution. A growing body of observational evidence suggests that the cluster environment is affecting not only the star formation histories of galaxies but also their very morphological properties.
The Coma Cluster Treasury Survey shall provide a key local, high-density benchmark for comparison to surveys of less dense environments (e.g., the Virgo, Fornax and Perseus galaxy clusters), high-redshift HST cluster surveys, and field surveys such as HUDF, GOODS and GEMS.