NOAO >   Observing Info >   Approved Programs >   2004B-0219

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Proposal Information for 2004B-0219


PI: Marc E. Zimer, MPE, mzimer@mpe.mpg.de
Address: Giessenbachstrasse, Postfach 1312, Garching 85741, Germany

CoI: Alexis Finoguenov, MPE
CoI: Trevor Ponman, University of Birmingham, UK
CoI: Hans Boehringer, MPE

Title: The Study of X-Ray Luminous Groups

Abstract: Groups of galaxies and clusters of galaxies should follow the same relationship between the velocity dispersion \sigma and the X-ray temperature T. However, in the literature exist a controversy between different authors. To adequately compare the properties of groups and clusters requires well-determined X-ray temperatures and optical velocity dispersions. While these quantities generally exist for rich clusters, the properties of groups are often poorly determined. In particular, the velocity dispersion could be wrong by underestimating \sigma due to low statistics with only a few galaxy redshifts and by groups which could have significant substructure and not being relaxed. Accurate X-ray temperature has been determined by XMM Newton for our groups. Therefore we propose to use Hydra on WIYN to study these critical groups which could bias the \sigma - T relation. We shall use the HYDRA data to : 1) increase the membership for a sample of X-ray detected groups. 2) determine accurate velocity dispersions for groups with well-known X-ray temperature. 3) study the dynamics and morphology of these groups. 4) constrain the \sigma - T relation for groups and clusters.


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