A 1.75 kpc/h Separation Dual AGN at z=0.36 in the COSMOS Field
  We present strong evidence for dual active galactic nuclei (AGN) in the
z=0.36 galaxy COSMOS J100043.15+020637.2. COSMOS Hubble Space Telescope (HST)
imaging of the galaxy shows a tidal tail, indicating that the galaxy recently
underwent a merger, as well as two bright point sources near the galaxy's
center. Both the luminosities of these sources (derived from the HST image) and
their emission line flux ratios (derived from Keck/DEIMOS slit spectroscopy)
suggest that both are AGN and not star-forming regions or supernovae.
Observations from zCOSMOS, Sloan Digital Sky Survey, XMM-Newton, Very Large
Array, and Spitzer fortify the evidence for AGN activity. With HST imaging we
measure a projected spatial offset between the two AGN of 1.75 +- 0.03 kpc/h,
and with DEIMOS we measure a 150 +- 40 km/s line-of-sight velocity offset
between the two AGN. Combined, these observations provide substantial evidence
that COSMOS J100043.15+020637.2 is a dual AGN in a merger-remnant galaxy.
