We present the HI content of 1580 early type galaxies (ETGs) in a total sample of 7747 galaxies that have HI measurements or upper limits from the ALFALFA survey. We find a significant correlation between HI content and local density, with HI detections almost exclusively in low-density environments. Using optical line ratios, we split the population into galaxies with spectral lines dominated by active galactic nuclei (AGN) and dominated by star forming regions. Compared with HI-rich star forming ETGs, HI-rich ETGs with AGN tend to be brighter and redder and to exhibit a stronger correlation between stellar mass and HI mass. This work is supported by NSF grant AST-1211005.
American Astronomical Society Meeting Abstracts #227
- Pub Date:
- January 2016