Molecular gas in the galaxy cluster Abell 262

CO observations of UGC 1347 and other galaxies of the cluster

¹ I. Physikalisches Institut, Universität zu Köln, Zülpicher Str. 77, 50937 Köln, Germany e-mail: bertram@ph1.uni-koeln.de
² NASA/Goddard Space Flight Center, Greenbelt, MD 20771, USA
³ European Southern Observatory, Karl-Schwarzschild-Str. 2, 85748 Garching, Germany

Received: 17 December 2004
Accepted: 23 September 2005

Abstract

We present millimeter CO line emission observations of 12 galaxies within the Abell 262 cluster, together with L_FIR data, in the context of a possible molecular gas deficiency within the region of the cluster center. Several indications of the presence of such a deficiency are highlighted and connected to a model of cirrus-like cloud stripping. The model predicts a drop in the average 100 μm flux density of galaxies in the core of the cluster compared to the average 100 μm flux density in the outer regions, which is actually indicated in the IRAS data of the cluster members. This drop is explained by the decrease in the total hydrogen column density N(H) and, therefore, also includes a decrease in the molecular gas content. 
In addition to results for the global CO content of the galaxy sample, high-resolution interferometric CO(1-0) observations of one of the cluster members, UGC 1347, exemplify the spatial distribution of the molecular gas in a galaxy of the cluster. With these observations, it was possible to confirm the existence of a bright off-nuclear CO-emission source and to derive molecular masses and line ratios for this source and the nucleus.