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The nature and space density of fossil groups of galaxies
We describe the properties of a sample of galaxy groups with very unusual distributions of galaxy luminosities. The most extreme example has an X-ray luminosity similar to that of the Virgo cluster…
The GEMS project: X-ray analysis and statistical properties of the group sample
The Group Evolution Multiwavelength Study (GEMS) involves a multiwavelength study of a sample of 60 galaxy groups, chosen to span a wide range of group properties. Substantial ROSAT Position…
The intragroup medium in loose groups of galaxies
- S. F. Helsdon, T. Ponman
- Physics
- 2 February 2000
We have used the ROSAT PSPC to study the properties of a sample of 24 X-ray-bright galaxy groups, representing the largest sample examined in detail to date. Hot plasma models are fitted to the…
A ROSAT survey of Hickson's compact galaxy groups
- T. Ponman, P. Bourner, H. Ebeling, H. Böhringer
- Physics
- 1 November 1996
We report the results of an almost complete survey of the X-ray properties of Hickson's compact galaxy groups with the ROSAT PSPC. Diffuse X-ray emission is detected from 22 groups. We infer that hot…
The Birmingham-CfA cluster scaling project - III. Entropy and similarity in galaxy systems
- T. Ponman, A. Sanderson, A. Finoguenov
- Physics
- 2 April 2003
We examine profiles and scaling properties of the entropy of the intergalactic gas in a sample of 66 virialized systems, ranging in mass from single elliptical galaxies to rich clusters, for which we…
Gas entropy in a representative sample of nearby X-ray galaxy clusters (REXCESS): relationship to gas mass fraction
We examine the radial entropy distribution and its scaling using 31 nearby galaxy clusters from the Representative XMM-Newton Cluster Structure Survey (REXCESS), a sample in the temperature range 2-9…
Chandra Observation of Abell 2142: Survival of Dense Subcluster Cores in a Merger
- M. Markevitch, T. Ponman, P. Zhao
- Physics
- 14 January 2000
We use Chandra data to map the gas temperature in the central region of the merging cluster A2142. The cluster is markedly nonisothermal; it appears that the central cooling flow has been disturbed…
The Birmingham-CfA cluster scaling Project – I. Gas fraction and the M-Tx relation
- A. Sanderson, T. Ponman, U. Illinois
- Physics
- 3 January 2003
We have assembled a large sample of virialized systems, comprising 66 galaxy clusters, groups and elliptical galaxies with high-quality X-ray data. To each system we have fitted analytical profiles…
The thermal imprint of galaxy formation on X-ray clusters
- T. Ponman, D. B. Cannon, J. Navarro
- PhysicsNature
- 22 October 1998
It is widely believed that structure in the Universe evolves hierarchically—fluctuations in the primordial distribution of matter, amplified by gravity, collapse and merge to form progressively…
A High-Resolution Study of the Hydra A Cluster with Chandra: Comparison of the Core Mass Distribution with Theoretical Predictions and Evidence for Feedback in the Cooling Flow
The cooling flow cluster Hydra A was observed during the orbital activation and calibration phase of the Chandra Observatory. While the X-ray image of the cluster exhibits complex structure in the…
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