The GALEX Arecibo SDSS Survey (GASS)

TL;DR

The GASS survey aims to measure the neutral hydrogen content of about 1000 massive galaxies to understand the transition from star-forming to passive galaxy states, providing valuable data on galaxy evolution.

Contribution

This is the first large, homogeneous survey targeting the HI content of massive galaxies around the transition mass, filling a gap in understanding galaxy evolution.

Findings

First statistically significant sample of transition galaxies with measured gas and star formation properties.

Insights into how cold gas responds to different physical conditions in galaxies.

Data will help elucidate processes driving galaxy evolution from blue to red.

Abstract

The GALEX Arecibo SDSS Survey (GASS) is a large targeted survey that started at Arecibo in March 2008. GASS is designed to measure the neutral hydrogen content of ~1000 massive galaxies (with stellar mass Mstar > 10^10 Msun) at redshift 0.025<z<0.05, uniformly selected from the SDSS spectroscopic and GALEX imaging surveys. Our selected mass range straddles the recently identified "transition mass" (Mstar ~3x10^10 Msun) above which galaxies show a marked decrease in their present to past-averaged star formation rates. GASS will produce the first statistically significant sample of massive "transition" galaxies with homogeneously measured stellar masses, star formation rates and gas properties. The analysis of this sample will allow us to investigate if and how the cold gas responds to a variety of different physical conditions in the galaxy, thus yielding insights on the physical processes responsible for the transition between blue, star-forming and red, passively evolving galaxies. GASS will be of considerably legacy value not only in isolation but also by complementing ongoing HI-selected surveys.