报告题目：Impact of environment on molecular gas reservoirs probed in distant cluster and field galaxies

报 告  人：Helmut Dannerbauer (Instituto de Astrofísica de Canarias, Spain)

报告时间：2019-12-12 15:00:00

报告地点：天文楼212报告厅

摘要：

It is clear that galaxies in local clusters are different from those

in the field.  Environment must play an important role in shaping the ensemble

of galaxies.  However, we do not yet know when these physical processes are

initiated and what mechanisms directly impact how galaxies evolve. We are using

the Australian Telescope Compact Array (ATCA) and ALMA to study the role of

environment on the molecular gas content, the fuel of star formation, of

distant star-forming galaxies. These are the likely progenitors of elliptical

galaxies which dominate the light in local galaxy clusters. From our pilot

survey to search for low-surface brightness cold CO(1-0) molecular gas

emission, I present the discovery of massive extended CO gas reservoirs in

these star-forming galaxies that are located in the galaxy cluster in formation

surrounding the radio galaxy, MRC1138-262, the so-called Spiderweb

protocluster, 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 galaxy protoclusters, how the

galaxies may contribute to enriching and heating the proto-intracluster medium,

and how their star formation may be limited by their internal dynamics.

Furthermore, I will present results of our ATCA Large Program, CO ATCA Legacy

Archive of Star-Forming Galaxies (COALAS), based on our successful pilot

survey. Our sample consists of well-covered 'field'-targets and protocluster

galaxies. The ATCA CO(1-0) measurements of high-z star-forming galaxies at

different environments complement our ALMA observations of mid-J CO lines and

dust continuum of these sources. This survey significantly extends our study of

how environment impact the cold molecular gas content, gas excitation and

star-formation efficiency in cluster and field galaxies in the early universe.