Groups: Evolution

[N79-299A]

An evolving group - the galaxy group known as N79-299A consists of 19 catalogued galaxies. The X-ray contours (from the ROSAT PSPC) overlaid on the optical image above, show that the structure of the hot gas is complex. Since the gas traces the gravitational potential, this indicates that the group is currently being assembled by the merger of smaller units. Bright X-ray emission from individual large galaxies within the group can also be clearly seen.

 

The GEMS project

The evolution of galaxy groups is not well understood, but clues are available from the state of the intergalactic gas and the morphology and star-forming properties of the group galaxies. We have a major programme underway to investigate this: the Group Evolution Multiwavelength Study. This is based on a sample of 60 groups for which we have good ROSAT X-ray data, which define the propereties of the hot intergalactic gas in these systems. In collaboration with colleagues at Swinburne (Australia) and Liverpool, we are also obtaining optical imaging and spectroscopy of most of the group galaxies, and HI radio data for some of them. We will also be probing the X-ray properties of many of these systems in greater detail with XMM or Chandra. Comparison of the luminosity function, morphology and star forming properties of the galaxies with the temperature, density and morphology of the group gas will provide essential data for comparison with cosmological simulations - in collaboration with members of the VIRGO consortium.
 

Galaxy-group interactions

We are also studying the physical processes through which the galaxies in groups are affected by their environments. For example, galaxies travelling through the intergalactic medium will feel a "wind" which can strip out gas from within the galaxy to form a galaxy wake. Further details of our programme of observations and simulations of these processes can be found here.
 
 

Researchers: Trevor Ponman, Irini Sakelliou, Somak Raychaudhury, Laurence Jones, Ian Stevens, Ale Terlevich, Andy Read, Steve Helsdon, David Acreman, Ewan O'Sullivan, Alastair Sanderson

This page is maintained by David Henley, was written by Trevor Ponman and was last updated on