Understanding the baryonic profile of gas in and around dark matter halos, with application to fast radio bursts, metal absorption lines, and weak lensing

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Galaxies are immersed in large halos of ionized gas of unknown size and densities. In the next few years, observations of transient fast radio bursts will provide sparse maps of the gas distribution, complementing existing metal absorption line data sets. McQuinn and his collaborators will develop the tools necessary to interpret these combined data sets. The team will use both fully cosmological simulations and simpler models to understand how violent galactic feedback processes from stars and black holes shape these gas halos and influence galaxy formation. McQuinn and collaborators will mentor freshman undergraduates enrolled in the Pre-MAP program at the University of Washington, with the goal of engaging them in research early in their careers. Five undergraduate students will be offered summer research internships. The team will also give a series of public lectures in the Seattle area.Previous theoretical studies of the gas halos around galaxies have primarily relied on comparing metal absorption line observations with the predictions of complex cosmological simulations with particular implementations of stellar and black hole feedback. The team will develop more flexible models for the gas distribution, which will use empirical inputs as well as inputs motivated by zoom-in simulations. These models will be compared to FRB and metal absorption line measurements to make more general statements about the spatial distribution of the enriched gas. The models will also be used to understand how the distribution of gas around galaxies could affect cosmological constraints from weak lensing observations.This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.