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Title: RADIO-SELECTED BINARY ACTIVE GALACTIC NUCLEI FROM THE VERY LARGE ARRAY STRIPE 82 SURVEY

Abstract

Galaxy mergers play an important role in the growth of galaxies and their supermassive black holes. Simulations suggest that tidal interactions could enhance black hole accretion, which can be tested by the fraction of binary active galactic nuclei (AGNs) among galaxy mergers. However, determining the fraction requires a statistical sample of binaries. We have identified kiloparsec-scale binary AGNs directly from high-resolution radio imaging. Inside the 92 deg{sup 2} covered by the high-resolution Very Large Array survey of the Sloan Digital Sky Survey (SDSS) Stripe 82 field, we identified 22 grade A and 30 grade B candidates of binary radio AGNs with angular separations less than 5'' (10 kpc at z = 0.1). Eight of the candidates have optical spectra for both components from the SDSS spectroscopic surveys and our Keck program. Two grade B candidates are projected pairs, but the remaining six candidates are all compelling cases of binary AGNs based on either emission line ratios or the excess in radio power compared to the Hα-traced star formation rate. Only two of the six binaries were previously discovered by an optical spectroscopic search. Based on these results, we estimate that ∼60% of our binary candidates would be confirmed once wemore » obtain complete spectroscopic information. We conclude that wide-area high-resolution radio surveys offer an efficient method to identify large samples of binary AGNs. These radio-selected binary AGNs complement binaries identified at other wavelengths and are useful for understanding the triggering mechanisms of black hole accretion.« less

Authors:
 [1];  [2]; ;  [3];  [4];  [5]
  1. Department of Physics and Astronomy, University of Iowa, Iowa City, IA 52245 (United States)
  2. Department of Physics and Astronomy, University of Wyoming, Laramie, WY 82071 (United States)
  3. California Institute of Technology, 1200 East California Boulevard, Pasadena, CA 91125 (United States)
  4. National Radio Astronomy Observatory, P.O. Box O, Socorro, NM 87801 (United States)
  5. Institute for Astronomy, University of Hawaii, 2680 Woodlawn Drive, Honolulu, HI 96822 (United States)
Publication Date:
OSTI Identifier:
22364489
Resource Type:
Journal Article
Resource Relation:
Journal Name: Astrophysical Journal; Journal Volume: 799; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA)
Country of Publication:
United States
Language:
English
Subject:
79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; BLACK HOLES; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; COSMIC RADIO SOURCES; EMISSION SPECTRA; GALACTIC EVOLUTION; GALAXIES; GALAXY NUCLEI; RESOLUTION; STAR ACCRETION; STAR EVOLUTION; WAVELENGTHS

Citation Formats

Fu, Hai, Myers, A. D., Djorgovski, S. G., Yan, Lin, Wrobel, J. M., and Stockton, A. RADIO-SELECTED BINARY ACTIVE GALACTIC NUCLEI FROM THE VERY LARGE ARRAY STRIPE 82 SURVEY. United States: N. p., 2015. Web. doi:10.1088/0004-637X/799/1/72.
Fu, Hai, Myers, A. D., Djorgovski, S. G., Yan, Lin, Wrobel, J. M., & Stockton, A. RADIO-SELECTED BINARY ACTIVE GALACTIC NUCLEI FROM THE VERY LARGE ARRAY STRIPE 82 SURVEY. United States. doi:10.1088/0004-637X/799/1/72.
Fu, Hai, Myers, A. D., Djorgovski, S. G., Yan, Lin, Wrobel, J. M., and Stockton, A. 2015. "RADIO-SELECTED BINARY ACTIVE GALACTIC NUCLEI FROM THE VERY LARGE ARRAY STRIPE 82 SURVEY". United States. doi:10.1088/0004-637X/799/1/72.
@article{osti_22364489,
title = {RADIO-SELECTED BINARY ACTIVE GALACTIC NUCLEI FROM THE VERY LARGE ARRAY STRIPE 82 SURVEY},
author = {Fu, Hai and Myers, A. D. and Djorgovski, S. G. and Yan, Lin and Wrobel, J. M. and Stockton, A.},
abstractNote = {Galaxy mergers play an important role in the growth of galaxies and their supermassive black holes. Simulations suggest that tidal interactions could enhance black hole accretion, which can be tested by the fraction of binary active galactic nuclei (AGNs) among galaxy mergers. However, determining the fraction requires a statistical sample of binaries. We have identified kiloparsec-scale binary AGNs directly from high-resolution radio imaging. Inside the 92 deg{sup 2} covered by the high-resolution Very Large Array survey of the Sloan Digital Sky Survey (SDSS) Stripe 82 field, we identified 22 grade A and 30 grade B candidates of binary radio AGNs with angular separations less than 5'' (10 kpc at z = 0.1). Eight of the candidates have optical spectra for both components from the SDSS spectroscopic surveys and our Keck program. Two grade B candidates are projected pairs, but the remaining six candidates are all compelling cases of binary AGNs based on either emission line ratios or the excess in radio power compared to the Hα-traced star formation rate. Only two of the six binaries were previously discovered by an optical spectroscopic search. Based on these results, we estimate that ∼60% of our binary candidates would be confirmed once we obtain complete spectroscopic information. We conclude that wide-area high-resolution radio surveys offer an efficient method to identify large samples of binary AGNs. These radio-selected binary AGNs complement binaries identified at other wavelengths and are useful for understanding the triggering mechanisms of black hole accretion.},
doi = {10.1088/0004-637X/799/1/72},
journal = {Astrophysical Journal},
number = 1,
volume = 799,
place = {United States},
year = 2015,
month = 1
}
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