CfA OIR Division Lunch Talks
Wednesday, December 5, 2012, 11:00 am, Pratt Conference Room

Gas-rich galaxies in the Arecibo Legacy Fast ALFA survey

Shan Huang (Cornell)

The Arecibo Legacy Fast ALFA (ALFALFA) survey is an extragalactic blind HI-line survey conducted with the 7-beam ALFA feed array on the 305-m telescope. The superior sensitivity, spectral and angular resolution, and sky coverage of ALFALFA provide the first full census of HI-bearing objects over a cosmologically significant volume of the local universe. It enables the study of HI-selected galaxies, from the most massive gaseous disks with HI mass above 10^10 M_sun to the lowest HI mass dwarf galaxies with HI mass below 10^7.7 M_sun. Making use of the latest ALFALFA catalog and the UV/optical data, we study the global scaling relationships for 9417 common galaxies (alpha.40-SDSS-GALEX). ALFALFA galaxies are found to be gas rich and biased against the red sequence. The lower star formation efficiencies of the very gas-rich galaxies may be explained if they reside preferentially in dark matter halos with high spin parameters.