MUSEQuBES CGM Surveys: From Low-z Star-forming Galaxies to High-z Lyman-alpha Emitters

Gas accretion and galactic winds are the two most important and yet the most poorly understood ingredients of galaxy evolution models. The gas consumption timescale for galaxies is typically < a few Gyr, suggesting that a continuous supply of cool gas is required for fueling observed star formation. On the other hand, models in which most of the accreted gas is converted into stars predict stellar masses that are far too high. It is widely believed that expulsion and heating of the infalling gas due to large-scale winds driven by massive stars (for low-mass galaxies) and/or active galactic nuclei (for high-mass galaxies) are the solution to this "overcooling" problem. Over the last decade, there is a growing consensus that the physical and chemical properties of the circumgalactic medium (CGM) retain imprints of these two crucial processes. However, owing to the low density, direct detection of the CGM in emission is beyond the reach of present day, and even next generation, large telescopes. Quasar absorption line spectroscopy is a proven technique to probe the elusive CGM. To this end, we are conducting two major surveys on the CGM using ~120 hours of MUSE GTO observations. Our high-z (z>3) sample comprises ~100 Lyman alpha emitters and the low-z (z<1) sample comprises ~300 low-mass, star-forming galaxies. We use high S/N spectra of background quasars, obtained with the VLT/UVES (for high-z) and HST/COS (for low-z), to study the CGM of these galaxies using absorption line spectroscopy. An overview of the initial results of these surveys will be presented in the talk. In particular, the dependence of the CGM properties on the SFRs, stellar masses, impact parameters, and redshifts of the galaxies will be discussed. The prospects of such studies, with the advent of upcoming next-generation large telescopes, such as TMT, will also be discussed in brief.