Chandra Observations of A 1.9 Kpc Separation Double X-Ray Source in A Candidate Dual Active Galactic Nucleus Galaxy At Z=0.16

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Comerford, Julia M.
Pooley, David
Gerke, Brian F.
Madejski, Greg M.

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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 active galactic nucleus (AGN) candidate based on the double-peaked [O III] lambda 5007 emission lines, with a line-of-sight velocity separation of 350 km s(-1), in its Sloan Digital Sky Survey spectrum. We used the Kast Spectrograph at Lick Observatory to obtain two long-slit spectra of the galaxy at two different position angles, which reveal that the two Type 2 AGN emission components have not only a velocity offset, but also a projected spatial offset of 1.9 h(70)(-1) kpc on the sky. Chandra/ACIS observations of two X-ray sources with the same spatial offset and orientation as the optical emission suggest that the galaxy most likely contains Compton-thick dual AGNs, 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.



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Comerford, Julia M., David Pooley, Brian F. Gerke, and Greg M. Madejski. "Chandra Observations of a 1.9 kpc Separation Double X-Ray Source in a Candidate Dual Active Galactic Nucleus Galaxy at z= 0.16." The Astrophysical Journal Letters, Vol. 737, No. 1 (Aug., 2011): L19.