Thesis Supervisor: Martin Zwaan

Co-Supervisors:€аRob Ivison, Andy Biggs
External collaborators: Celine P†йroux, Ivan Oteo, Ian Smail

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Abstract:

Background
Observational advances over the last decade have provided tremendous insight into the formation and evolution of galaxies and the stars they contain. Most of these studies focus on understanding the build-up of stellar mass, and hence concentrate on measuring the energy emitted by stars and stellar products. The stellar mass density has grown by a factor thirty since z=2 and the most significant increase happened over a period of a few Gyr from z~2 to z~1. In agreement with these results is the observation that the cosmic star formation rate density reaches a peak around the same redshift range.

But our understanding of galaxy evolution can only be complete when the most fundamental galactic component - cold gas - is also taken into account. Cold gas provides the fuel for the formation of stars and many of the properties of galaxies are determined by the amount of gas they contain, and specifically, how efficient they are in converting their innate gas content into stars. It is therefore essential to probe the evolution of cold gas over cosmic time. Neutral hydrogen provides the essential fuel, but this fuel has to cool and transform to the molecular phase in order to provide the necessary conditions for star formation. Therefore, observations of the evolution of the molecular gas provide a much more direct link to star formation over cosmic time.

The project: ALMACAL
We are currently exploiting ALMA calibration observations to carry out a novel, wide and deep submm survey: ALMACAL. Using calibrators it is possible to carry out such a deep survey with the necessary data coming тАШfor freeтАЩ from science projects dedicated to a wide variety of astrophysical topics. These calibration data comprise a large number of observations in a variety of frequency bands and array configurations.

We have already processed many hundreds of calibrator observations, but the ALMACAL data base is expected to grow immensely in the near future, with ALMA observations getting more efficient. In essence, ALMACAL is the most comprehensive ALMA observing project ever, in terms of observing time and the science topics it addresses.

We are looking for an enthusiastic PhD student who is interested in working with us in using ALMACAL to address exciting and topical science questions related to the evolution of molecular gas in galaxies. The focus will initially be on molecular absorption lines, but there are possibilities to extend the study to blind CO emission line surveys, quasar jets, high resolution studies of sub-millimetre galaxies, etc.

The student will be part of a large team of scientists (not limited to ESO) with a huge accumulated experience in the role of gas in galaxy evolution and (sub)-millimetre observations.