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.
