2016/06/03 by R. Scott Barrows, Julia M. Comerford, Jenny E. Greene +1
Physics and Astronomy · #Active galactic nucleus #Astronomy and Astrophysical Research #Extragalactic astronomy #Galaxies: Formation, Evolution, Phenomena #Galaxy #Galaxy formation and evolution #Gamma-ray bursts and supernovae #Offset (computer science) #Sky #astro-ph.CO #astro-ph.GA
paper · pdf · doi:10.3847/0004-637x/829/1/37
Accepted for publication in The Astrophysical Journal, 24 pages, 8 figures, 4 tables
arxiv created 2016/06/03 · openalex created_date 2016/06/24 · openalex publication_date 2016/09/20 · arxiv updated 2016/09/28 · openalex updated_date 2026/08/06
ABSTRACT We present a sample of 18 optically selected and X-ray-detected spatially offset active galactic nuclei (AGNs) from the Sloan Digital Sky Survey (SDSS). In nine systems, the X-ray active galactic nucleus (AGN) is spatially offset from the galactic stellar core that is located within the 3″ diameter SDSS spectroscopic fiber. In 11 systems, the X-ray AGN is spatially offset from a stellar core that is located outside the fiber, with an overlap of two. To build the sample, we cross-matched Type II AGNs selected from the SDSS galaxy catalog with archival Chandra imaging and employed our custom astrometric and registration procedure. The projected angular (physical) offsets span a range of 0.″6 (0.8 kpc) to 17.″4 (19.4 kpc), with a median value of 2.″7 (4.6 kpc). The offset nature of an AGN is an unambiguous signature of a galaxy merger, and these systems can be used to study the properties of AGNs in galaxy mergers without the biases introduced by morphological merger selection techniques. In this paper (Paper I), we use our sample to assess the kinematics of AGN photoionized gas in galaxy mergers. We find that spectroscopic offset AGN selection may be up to % incomplete due to small projected velocity offsets. We also find that the magnitude of the velocity offsets are generally larger than expected if our spatial selection introduces a bias toward face-on orbits, suggesting the presence of complex kinematics in the emission line gas of AGNs in galaxy mergers.