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Title: Evidence for Merger-driven Growth in Luminous, High- z, Obscured AGNs in the CANDELS/COSMOS Field

While major mergers have long been proposed as a driver of both active galactic nucleus (AGN) activity and the $${M}_{\mathrm{BH}}\mbox{--}{\sigma }_{\mathrm{bulge}}$$ relation, studies of moderate to high-redshift Seyfert-luminosity AGN hosts have found little evidence for enhanced rates of interactions. However, both theory and observation suggest that while these AGNs may be fueled by stochastic accretion and secular processes, high-luminosity, high-redshift, and heavily obscured AGNs are the AGNs most likely to be merger-driven. To better sample this population of AGNs, we turn to infrared selection in the CANDELS/COSMOS field. Compared to their lower-luminosity and less obscured X-ray-only counterparts, IR-only AGNs (luminous, heavily obscured AGNs) are more likely to be classified as either irregular ($${50}_{-12}^{+12} \% $$ versus $${9}_{-2}^{+5} \% $$) or asymmetric ($${69}_{-13}^{+9} \% $$ versus $${17}_{-4}^{+6} \% $$) and are less likely to have a spheroidal component ($${31}_{-9}^{+13} \% $$ versus $${77}_{-6}^{+4} \% $$). Furthermore, IR-only AGNs are also significantly more likely than X-ray-only AGNs ($${75}_{-13}^{+8} \% $$ versus $${31}_{-6}^{+6} \% $$) to be classified either as interacting or merging in a way that significantly disturbs the host galaxy or as disturbed, though not clearly interacting or merging, which potentially represents the late stages of a major merger. Finally, this suggests that while major mergers may not contribute significantly to the fueling of Seyfert-luminosity AGNs, interactions appear to play a more dominant role in the triggering and fueling of high-luminosity heavily obscured AGNs.
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  1. Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
  2. Rochester Inst. of Technology, Rochester, NY (United States)
  3. Colby College, Waterville, ME (United States)
  4. Max Planck Inst. fur Extraterrestrische Physik, Garching (Germany)
  5. Istituto Nazionale di Astrofisica (INAF), Roma (Italy). Osservatorio Astronomico di Roma
  6. National Astronomical Observatory of Japan, Hilo, HI (United States). Subaru Telescope
  7. Harvard-Smithsonian Center for Astrophysics, Cambridge, MA (United States)
  8. Space Telescope Science Inst., Baltimore, MD (United States)
  9. Univ. of Connecticut, Storrs, CT (United States)
  10. Istituto Nazionale di Astrofisica (INAF), Bologna (Italy). Osservatorio Astronomico di Bologna
  11. Wheelock College, Boston, MA (United States). Dept. of Math & Science
  12. Univ. Nacional Autonoma de Mexico (UNAM), Ensenada, BC (Mexico). Inst. de Astronomia, Observatorio Astronomico Nacional; Univ. Autonoma de Ciudad Juarez, Juarez (Mexico). Inst. de Ingeniería y Tecnología
  13. Inst. de Astrofisica de Canarias, Tenerife (Spain)
  14. Univ. of Nottingham (United Kingdom). School of Physics & Astronomy
  15. Swinburne Univ. of Technology, Hawthorn, VIC (Australia). Centre for Astrophysics & Supercomputing
  16. Aix Marseille Univ., Marseille (France). Lab. d’Astrophysique de Marseille; Space Telescope Science Inst., Baltimore, MD (United States)
  17. City Univ. (CUNY), NY (United States). Astrophysical Observatory, Dept. of Engineering Science and Physics; American Museum of Natural History (AMNH), New York, NY (United States). Dept. of Astrophysics and Hayden Planetarium; City Univ. (CUNY), NY (United States). Physics Program, The Graduate Center
  18. Univ. of Alabama, Tuscaloosa, AL (United States). Dept. of Physics and Astronomy
  19. Univ. of Hawaii, Honolulu, HI (United States). Inst. for Astronomy
  20. Univ. of California, San Diego, CA (United States). Center for Astrophysics and Space Sciences
  21. Univ. of Bath, Bath (United Kingdom); Univ. of St. Andrews, Scotland (United Kingdom). Scottish Univ. Physics Alliance (SUPA)
  22. Durham Univ. (United Kingdom). Centre for Extragalactic Astronomy, Dept. of Physics
  23. Univ. of Michigan, Ann Arbor, MI (United States). Dept. of Astronomy
  24. Univ. of California, Santa Cruz, CA (United States). Lick Observatory, Dept. of Astronomy and Astrophysics
  25. Univ. of Missouri, Kansas City, MO (United States). Dept. of Physics and Astronomy
  26. Ehime Univ., Matsuyama (Japan). Research Center for Space and Cosmic Evolution
Publication Date:
Report Number(s):
Journal ID: ISSN 1538-4357
Grant/Contract Number:
AC52-06NA25396; HF-51303.01; NAS5-26555; NAS8-03060; AST-1004583
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 853; Journal Issue: 1; Journal ID: ISSN 1538-4357
Institute of Physics (IOP)
Research Org:
Los Alamos National Lab. (LANL), Los Alamos, NM (United States)
Sponsoring Org:
USDOE; National Aeronautics and Space Administration (NASA); National Science Foundation (NSF)
Country of Publication:
United States
79 ASTRONOMY AND ASTROPHYSICS; galaxies: active; infrared: galaxies; X-rays: galaxies
OSTI Identifier: