The Effect of AGN on the Global HI Content of Isolated Low-Mass Galaxies
  We investigate the global neutral hydrogen (HI) content of isolated galaxies
selected from the SDSS spectroscopic survey with optical evidence of Active
Galactic Nuclei (AGN). Our sample includes galaxies with unresolved HI
observations from the ALFALFA 70% data release combined with deeper HI
observations of low-mass galaxies with 7.0 < log(M*) < 9.5. We examine the HI
masses of this sample using the distance from the star-forming sequence on the
OIII\Hb and NII\Ha Baldwin Phillips Terlevich (BPT) diagram as a measurement of
AGN activity. In agreement with previous studies, we find that, for galaxies
with log(M*) > 9.5, AGN activity does not correlate with the global HI content.
However, for galaxies with 9.2 < log(M*) < 9.5, we identify a set of objects at
large distances from the BPT star-forming sequence and lower than expected HI
masses. This gas-depleted sample is red in both g-r and NUV-r colors and
compact without distinguishable signs of star formation. This is surprising
because the vast majority of isolated galaxies in this stellar mass regime are
both star-forming and gas-rich. These galaxies are greater than 1.5 Mpc from
any massive galaxy, ruling out environmental processes as a source of the
gas-depletion. We suggest that either black hole feedback or shocks from
extremely bursty star formation cause the emission lines and have destroyed or
otherwise consumed the cold gas.
