The X-ray Luminosity Function for Poor Clusters of Galaxies
Abstract
We will present the first X-ray Luminosity Function for poor clusters of galaxies. Using a percolation algorithm, White et al. (1996) has compiled a catalog of 600 optically selected groups composed of Zwicky galaxies. This catalog includes MKW and AWM groups (with cD galaxies), many Hickson compact groups, as well as many more loose condensations. We selected a complete,volume-limited subsample of these poor clusters which have at least 4 Zwicky galaxies, b>30deg , a surface density enhancement of ~50, and z <= 0.03. We then cross-correlated this sample with the ROSAT all-sky X-ray survey. About 50% of this sample of 50 clusters was detected with 0.5-2.0 keV X-ray luminosities >4 x 10(41) h75(-2) ergs/sec. These are the X-ray brightest groups in the northern sky. From this sample, we constructed an X-ray Luminosity Function. We find that this poor cluster luminosity function matches well with that derived for Abell clusters by Briel & Henry (1993). It appears that these groups are low mass extensions of rich clusters. We have also derived a mass function for these groups assuming that the X-ray emission is in hydrostatic equilibrium within the clusters. We will compare this mass function with those expected from different cosmological models with different values of Omega . This research was funded by NSF grant AST93-17596 and NASA grant NAGW-3152.
- Publication:
-
American Astronomical Society Meeting Abstracts
- Pub Date:
- December 1995
- Bibcode:
- 1995AAS...187.9501B