Chandra Observations of a 1.9 kpc Separation Double X-ray Source in a
  Candidate Dual AGN Galaxy at z=0.16
  We report Chandra observations of a double X-ray source in the z=0.1569
galaxy SDSS J171544.05+600835.7. The galaxy was initially identified as a dual
AGN candidate based on the double-peaked [O III] emission lines, with a
line-of-sight velocity separation of 350 km/s, in its Sloan Digital Sky Survey
spectrum. We used the Kast Spectrograph at Lick Observatory to obtain two
longslit spectra of the galaxy at two different position angles, which reveal
that the two AGN emission components have not only a velocity offset, but also
a projected spatial offset of 1.9 kpc/h70 on the sky. Chandra/ACIS observations
of two X-ray sources with the same spatial offset and orientation as the
optical emission suggest the galaxy most likely contains Compton-thick dual
AGN, although the observations could also be explained by AGN jets. Deeper
X-ray observations that reveal Fe K lines, if present, would distinguish
between the two scenarios. The observations of a double X-ray source in SDSS
J171544.05+600835.7 are a proof of concept for a new, systematic detection
method that selects promising dual AGN candidates from ground-based
spectroscopy that exhibits both velocity and spatial offsets in the AGN
emission features.
