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13th of September 2017
ATNF Colloquium
Surprising existence of massive and large molecular gas reservoirs in a distant protocluster
by Helmut Dannerbauer (Instituto de Astrofísica de Canarias)
Abstract. Galaxies in local clusters are significantly affected by environmental effects. However, we do not yet know when these physical processes are initiated and what mechanisms in clusters directly impact the course of galaxy evolution. We are using the Australian Telescope Compact Array (ATCA) to search for low-surface brightness emission of cold molecular gas, the fuel of star formation, in protoclusters galaxies and their halos. These galaxies are the progenitors of elliptical galaxies which dominate local galaxy clusters. I present the discovery of massive and large CO gas reservoirs in these star-forming galaxies which are located in the protocluster surrounding the radio galaxy, MRC1138-262, at z=2.2. The discovery is unexpected as gas truncation and stripping was predicted. Our results alter our view of the important topics of the development and gas phase distribution of the "proto-intracluster medium": how ram pressure stripping may operate in protoclusters, how the galaxies may contribute to the proto-intracluster medium and how their star formation may be limited by dynamics. Finally, I present our new ATCA Large Program, COALAS (CO ATCA Legacy Archive of Star-Forming Galaxies), which will extend significantly our study of environmental effects on cluster and field galaxies.

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