Galaxies 09: Assembly, Gas Content and Star Formation History of Galaxies
Timothy Heckman
Johns Hopkins University
The GALEX Arecibo SDSS Survey (GASS)
The GALEX Arecibo SDSS Survey (GASS) is designed to measure the HI
properties of 1000 galaxies with SDSS spectra and optical images and GALEX
ultraviolet images. These galaxies are selected to fairly sample the entire
galaxy population over the range of stellar mass between $10^{10}$ and $10^{11.5}$
solar masses over the redshift range 0.025 to 0.05 and down to a limit of
$M_{HI}/M_{*}$ = 1.5\%. I will present preliminary results based on the first 250
galaxies, and also summarize results from a pilot program with IRAM to
measure the molecular gas. We find strong scaling relations between the HI
content and both the stellar population and structural properties of the
galaxies. We find candidates for recent accretion events (very high HI mass
fractions in otherwise normal red and dead early type galaxies) as well as
candidates for on-going quenching of star formation (galaxies with
significant recent star formation but little or no HI). The implications for
our understanding of galaxy evolution will be briefly summarized.
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