Galaxy evolution: Tracing the gas fraction of star-forming galaxies

Research Project, 2016 – 2019

The topic of galaxy formation and evolution is a fundamental part of modern astrophysics. Improving our understanding of this topic has direct implications on the study of our Milky Way as well as cosmology. In this project we look back 10-13 billion years in time to study galaxies during this epoch of intense star formation. Galaxies have been found to grow through two different modes, mergers that often cause intense starburst and the slower cold-mode accretion of gas from outside the galaxies. Much progess has been made in terms of understanding the stellar growth, however, it still remains to be understood how the gas fraction evolves in galaxies across different mass ranges and classes of galaxies. The project has three different aims: [1] estimate the gas-fraction of star-forming galaxies at redshift z=2-7, [2] compare the molecular gas estimates with other tracers such as dust continuum and atomic fine-structure lines, and [3] develop a spectral line stacking algorithm. Concerning aim [3], we have recently published a novel continuum stacking tool for radio and mm interferometric data, which operates directly on the calibrated visibility data, and this has attracted attention from several international groups including those who are planning for future surveys. The project is planned to run over four years during the period 2016-2019 and majority of it will be the objective of a PhD position that will be located in the Radioastronomy and astrophysics group at Chalmers. Chalmers is an ideal location for this project due to the presence of my own research group along with other extragalactic astronomers, and National Facility for Radio Astronomy in Sweden (including the Nordic ALMA regional centre node). The data to be utilized come from both our current projects, collaboration with other teams, and through future projects. The project is timely, both in terms of the general interest in the methodology as well as the scientific purpose of the rapidly developing field of galaxy evolution. We will be using data from state-of-the telescopes such as ALMA and VLA. The results will have implication on how we understand the building blocks of present day galaxies like the Milky Way.