Observation of the Coma cluster of galaxies with ROSAT during the all-sky-survey.
Abstract
The Coma cluster of galaxies was observed with the position sensitive proportional counter (PSPC) during the ROSAT all sky survey. We find evidence for substructure in this cluster. Diffuse X-ray emission is detected from the regions of the NGC 4839 and 4911 subgroups at 6% and 1% of the total cluster emission respectively. There may be emission associated with the NGC 4874 and 4889 subgroups as well. The NGC 4839 group appears to be in the process of merging with the cluster. These X-ray data show that at least some of the groups previously found in projection are in fact physical objects possessing potential wells deep enough to trap their own X-ray gas. Because of the unlimited field of view of the all sky survey and the low background of the PSPC, we were able to measure the azimuthally averaged surface brightness of Coma out to approximately 100 arcmin, twice as far as was previously possible. Given the validity of our mass models, these new X-ray data imply that within 5h^-1^_50_ Mpc the binding mass of the Coma cluster is 1.8 +/- 0.6 x 10^15^ h^-1^_50_ M_sun_ and the fraction of cluster mass contained in hot gas is 0.301 +/- 0.14h^-3/2^_50^. Furthermore, the binding mass is more centrally concentrated than is the X-ray gas.
- Publication:
-
Astronomy and Astrophysics
- Pub Date:
- June 1992
- Bibcode:
- 1992A&A...259L..31B
- Keywords:
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- Cosmology;
- Galactic Clusters;
- Rosat Mission;
- Sky Surveys (Astronomy);
- X Ray Imagery;
- Galactic Mass;
- X Ray Astronomy;
- X Ray Sources;
- Astrophysics