Understanding dual active galactic nucleus activation in the nearby Universe. (2012)
Keywords :
galaxies active - galaxies: interactions - X-rays: galaxies
Abstract:We study the fraction of dual active galactic nuclei (AGNs) in a sample of 167 nearby (z < 0.05), moderate-luminosity, ultra-hard X-ray-selected AGNs from the all-sky Swift Burst Alert Telescope (BAT) survey. Combining new Chandra and Gemini observations together with optical and X-ray observations, we find that the dual AGN frequency at scales <100 kpc is ~10% (16/167). Of the 16 dual AGNs, only 3 (19%) were detected using X-ray spectroscopy and were not detected using emission line diagnostics. Close dual AGNs (<30 kpc) tend to be more common among the most X-ray luminous systems. In dual AGNs, the X-ray luminosity of both AGNs increases strongly with decreasing galaxy separation, suggesting that the merging event is key in powering both
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The Burst Alert Telescope (BAT) AGN sample consists of 167 nearby
(z<0.05) ultra-hard X-ray BAT-detected AGNs from Koss et al. (2011,
Cat. J/ApJ/739/57) catalog in the Northern sky (>-25{deg}), with low
Galactic extinction (E(B-V)<0.5). For each BAT AGN, we search the
SDSS, 6DF, 2DF, and NED for apparent companions within 100kpc with
small radial velocity differences (<300km/s). To determine the AGN
nature of the galaxy companions, we use X-ray data from Chandra, XRT,
or XMM.
- B/chandra : The Chandra Archive Log (CXC, 1999-2013)
- B/xmm : XMM-Newton Obs. Log (XMM-Newton Science Operation Center, 2012)
- II/306 : The SDSS Photometric Catalog, Release 8 (Adelman-McCarthy+, 2011)
- VII/259 : 6dF galaxy survey final redshift release (Jones+, 2009)
- II/268 : The 2dF QSO Redshift Survey Input Catalogue (Smith+ 2005)
- VII/241 : The 2dF QSO Redshift Survey (Croom+ 2004)
- VII/250 : The 2dF Galaxy Redshift Survey (2dFGRS) (2dFGRS Team, 1998-2003)
- J/ApJ/728/58 : Swift-BAT survey of AGNs (Burlon+, 2011)
- J/ApJ/739/57 : Ultra hard X-ray AGNs in the Swift/BAT survey (Koss+, 2011)
- J/A+A/524/A64 : The 54-month Palermo BAT-survey catalogue (Cusumano+, 2010)
- J/A+A/510/A48 : Palermo Swift-BAT Hard X-ray Catalogue (Cusumano+, 2010)
- J/ApJ/681/113 : Swift BAT survey of AGNs (Tueller+, 2008)
- J/ApJ/678/102 : BAT X-ray survey. I. (Ajello+, 2008)
- J/ApJ/633/L77 : SWIFT/BAT detections of AGN (Markwardt+, 2005)
- http://www.sdss.org/ : SDSS Web site