HI gas in the Milky Way

sponge_footprint

Locations of 21-SPONGE sources on the sky. The black lines contain the sky region viewable by the Arecibo observatory.

Interstellar neutral hydrogen gas (HI) is a key ingredient for star formation and galaxy evolution throughout cosmic time.  The Galactic absorption-line survey “21-cm SPectral line Observations of Neutral Gas with the EVLA” (21-SPONGE) is providing some of the most sensitive observations of the neutral interstellar medium (ISM) to date. As a member of the 21-SPONGE team, I am working to compare 21-SPONGE observations to hydrodynamic numerical simulations to constrain the ISM’s physical conditions (e.g., the temperature and density distributions) to better understand the initial conditions of star formation and help guide the numerical prescription of star formation in cosmological simulations.