Incidence of WISE-Selected Obscured AGNs in Major Mergers and
  Interactions from the SDSS
  We use the Wide-field Infrared Survey Explorer (WISE) and the Sloan Digital
Sky Survey (SDSS) to confirm a connection between dust-obscured active galactic
nuclei (AGNs) and galaxy merging. Using a new, volume-limited (z <= 0.08)
catalog of visually-selected major mergers and galaxy-galaxy interactions from
the SDSS, with stellar masses above 2x10^10 Msun, we find that major mergers
(interactions) are 5-17 (3-5) times more likely to have red [3.4]-[4.6] colors
associated with dust-obscured or `dusty' AGNs, compared to non-merging galaxies
with similar masses. Using published fiber spectral diagnostics, we map the
[3.4]-[4.6] versus [4.6]-[12] colors of different emission-line galaxies and
find one-quarter of Seyferts have colors indicative of a dusty AGN. We find
that AGNs are five times more likely to be obscured when hosted by a merging
galaxy, half of AGNs hosted by a merger are dusty, and we find no enhanced
frequency of optical AGNs in merging over non-merging galaxies. We conclude
that undetected AGNs missed at shorter wavelengths are at the heart of the
ongoing AGN-merger connection debate. The vast majority of mergers hosting
dusty AGNs are star-forming and located at the centers of Mhalo<10^13 Msun
groups. Assuming plausibly short duration dusty-AGN phases, we speculate that a
large fraction of gas-rich mergers experience a brief obscured AGN phase, in
agreement with the strong connection between central star formation and black
hole growth seen in merger simulations.
