AAS 207th Meeting, 8-12 January 2006
Session 149 AGN: Host Galaxies and Clustering
Oral, Wednesday, 10:00-11:30am, January 11, 2006, Salon 1

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[149.06] ROSAT X-ray Properties of 2MASS Galaxy Clusters

X. Dai, C. S. Kochanek, N. D. Morgan (The Ohio State University)

We stacked the X-ray images from the ROSAT All Sky Survey for over 4,000 clusters selected from the 2MASS catalog and binned in five richness bins. We detected excess X-ray emission over background at the center of the stacked images in all five richness bins. We studied the X-ray properties of the stacked images including their surface brightness profiles, temperatures, soft X-ray luminosities, and entropy profiles. We obtained typical LX-T and other relations between X-ray and optical properties indicating that the cluster selection method is working properly down to clusters in the poorest richness bin. We further binned the clusters into redshift sub-bins and did not find significant redshift dependent biases from the optically selection methods as the luminosities in redshift sub-bins are consistent with each other. Our results demonstrate that stacking of RASS data from optically selected clusters can be a powerful tool to explore possible biases from the cluster selection algorithm. In addition, with the large ensemble of clusters especially for groups, we confirm the steepening of the LX-T relation in the group regime and the deviation of the S-T relation from the simple scaling relation.

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