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Title: Merger-driven fueling of active galactic nuclei: Six dual and of AGNs discovered with Chandra and Hubble Space Telescope observations

Abstract

Dual active galactic nuclei (AGNs) and offset AGNs are kpc-scale separation supermassive black holes pairs created during galaxy mergers, where both or one of the black holes are AGNs, respectively. These dual and offset AGNs are valuable probes of the link between mergers and AGNs but are challenging to identify. Here we present Chandra/ACIS observations of 12 optically selected dual AGN candidates at $$z\lt 0.34$$, where we use the X-rays to identify AGNs. We also present Hubble Space Telescope/Wide Field Camera 3 observations of 10 of these candidates, which reveal any stellar bulges accompanying the AGNs. We discover a dual AGN system with separation $${\rm \Delta }x=2.2$$ kpc, where the two stellar bulges have coincident [O iii] λ5007 and X-ray sources. This system is an extremely minor merger (460:1) that may include a dwarf galaxy hosting an intermediate mass black hole. We also find six single AGNs, and five systems that are either dual or offset AGNs with separations $${\rm \Delta }x\lt 10$$ kpc. Four of the six dual AGNs and dual/offset AGNs are in ongoing major mergers, and these AGNs are 10 times more luminous, on average, than the single AGNs in our sample. This hints that major mergers may preferentially trigger higher luminosity AGNs. Further, we find that confirmed dual AGNs have hard X-ray luminosities that are half of those of single AGNs at fixed [O III] λ5007 luminosity, on average. Lastly, this could be explained by high densities of gas funneled to galaxy centers during mergers, and emphasizes the need for deeper X-ray observations of dual AGN candidates.

Authors:
 [1];  [2];  [1];  [3];  [4];  [5];  [6]
  1. Univ. of Colorado, Boulder, CO (United States)
  2. Sam Houston State Univ., Huntsville, TX (United States); Eureka Scientific, Inc., Oakland, CA (United States)
  3. Princeton Univ., Princeton, NJ (United States)
  4. Johns Hopkins Univ., Baltimore, MD (United States)
  5. SLAC National Accelerator Lab., Menlo Park, CA (United States)
  6. Univ. of California, Irvine, CA (United States)
Publication Date:
Research Org.:
SLAC National Accelerator Lab., Menlo Park, CA (United States)
Sponsoring Org.:
National Aeronautics and Space Administration (NASA); USDOE Office of Science (SC)
OSTI Identifier:
1313952
Report Number(s):
SLAC-PUB-16790
Journal ID: ISSN 1538-4357; arXiv:1504.01391
Grant/Contract Number:  
AC02-76SF00515
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 806; Journal Issue: 2; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; astrophysics; ASTRO; GRQC; galaxies: active; galaxies: interactions; galaxies: nuclei

Citation Formats

Comerford, Julia M., Pooley, David, Barrows, R. Scott, Greene, Jenny E., Zakamska, Nadia L., Madejski, Greg M., and Cooper, Michael C. Merger-driven fueling of active galactic nuclei: Six dual and of AGNs discovered with Chandra and Hubble Space Telescope observations. United States: N. p., 2015. Web. doi:10.1088/0004-637X/806/2/219.
Comerford, Julia M., Pooley, David, Barrows, R. Scott, Greene, Jenny E., Zakamska, Nadia L., Madejski, Greg M., & Cooper, Michael C. Merger-driven fueling of active galactic nuclei: Six dual and of AGNs discovered with Chandra and Hubble Space Telescope observations. United States. doi:10.1088/0004-637X/806/2/219.
Comerford, Julia M., Pooley, David, Barrows, R. Scott, Greene, Jenny E., Zakamska, Nadia L., Madejski, Greg M., and Cooper, Michael C. Fri . "Merger-driven fueling of active galactic nuclei: Six dual and of AGNs discovered with Chandra and Hubble Space Telescope observations". United States. doi:10.1088/0004-637X/806/2/219. https://www.osti.gov/servlets/purl/1313952.
@article{osti_1313952,
title = {Merger-driven fueling of active galactic nuclei: Six dual and of AGNs discovered with Chandra and Hubble Space Telescope observations},
author = {Comerford, Julia M. and Pooley, David and Barrows, R. Scott and Greene, Jenny E. and Zakamska, Nadia L. and Madejski, Greg M. and Cooper, Michael C.},
abstractNote = {Dual active galactic nuclei (AGNs) and offset AGNs are kpc-scale separation supermassive black holes pairs created during galaxy mergers, where both or one of the black holes are AGNs, respectively. These dual and offset AGNs are valuable probes of the link between mergers and AGNs but are challenging to identify. Here we present Chandra/ACIS observations of 12 optically selected dual AGN candidates at $z\lt 0.34$, where we use the X-rays to identify AGNs. We also present Hubble Space Telescope/Wide Field Camera 3 observations of 10 of these candidates, which reveal any stellar bulges accompanying the AGNs. We discover a dual AGN system with separation ${\rm \Delta }x=2.2$ kpc, where the two stellar bulges have coincident [O iii] λ5007 and X-ray sources. This system is an extremely minor merger (460:1) that may include a dwarf galaxy hosting an intermediate mass black hole. We also find six single AGNs, and five systems that are either dual or offset AGNs with separations ${\rm \Delta }x\lt 10$ kpc. Four of the six dual AGNs and dual/offset AGNs are in ongoing major mergers, and these AGNs are 10 times more luminous, on average, than the single AGNs in our sample. This hints that major mergers may preferentially trigger higher luminosity AGNs. Further, we find that confirmed dual AGNs have hard X-ray luminosities that are half of those of single AGNs at fixed [O III] λ5007 luminosity, on average. Lastly, this could be explained by high densities of gas funneled to galaxy centers during mergers, and emphasizes the need for deeper X-ray observations of dual AGN candidates.},
doi = {10.1088/0004-637X/806/2/219},
journal = {The Astrophysical Journal (Online)},
number = 2,
volume = 806,
place = {United States},
year = {2015},
month = {6}
}

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