New insight into the growth of galaxies: Finding cold gas in massive dark matter halos, Hsiao-Wen Chen and Jean-Rene Gauthier

One of the outstanding questions in galactic cosmology is the detailed process by which galaxies acquire gas from the surrounding intergalactic medium, and how this process varies with galaxy mass and redshift. The rate at which gas is being accreted, and the fraction of hot and cold gas within the dark matter halos of galaxies are key factors in developing a clearer picture of disk and star formation. Numerical simulations that incorporate the complex baryonic physics of gas accretion are just beginning to probe these processes, and techniques for observing cold gas in galactic halos are essential.

New observations by KICP scientists, led by faculty member Hsiao-Wen Chen, graduate student Jean-Rene Gauthier and former KICP fellow Jeremy Tinker, have detected the presence of cold gas in the dark matter halos around luminous red galaxies, which are typically ten to one hundred times more massive than the Milky Way. Their data provide critical input for understanding the growth of these large systems, and an important complement to recent observations of cold gas around smaller galaxies. [more]