ENSEMBLE VARIABILITY OF NEAR-INFRARED-SELECTED ACTIVE GALACTIC NUCLEI

Kouzuma, S; Yamaoka, H

doi:10.1088/0004-637X/747/1/14

Title: ENSEMBLE VARIABILITY OF NEAR-INFRARED-SELECTED ACTIVE GALACTIC NUCLEI

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Abstract

We present the properties of the ensemble variability V for nearly 5000 near-infrared active galactic nuclei (AGNs) selected from the catalog of Quasars and Active Galactic Nuclei (13th Edition) and the SDSS-DR7 quasar catalog. From three near-infrared point source catalogs, namely, Two Micron All Sky Survey (2MASS), Deep Near Infrared Survey (DENIS), and UKIDSS/LAS catalogs, we extract 2MASS-DENIS and 2MASS-UKIDSS counterparts for cataloged AGNs by cross-identification between catalogs. We further select variable AGNs based on an optimal criterion for selecting the variable sources. The sample objects are divided into subsets according to whether near-infrared light originates by optical emission or by near-infrared emission in the rest frame; and we examine the correlations of the ensemble variability with the rest-frame wavelength, redshift, luminosity, and rest-frame time lag. In addition, we also examine the correlations of variability amplitude with optical variability, radio intensity, and radio-to-optical flux ratio. The rest-frame optical variability of our samples shows negative correlations with luminosity and positive correlations with rest-frame time lag (i.e., the structure function, SF), and this result is consistent with previous analyses. However, no well-known negative correlation exists between the rest-frame wavelength and optical variability. This inconsistency might be due to a biased sampling ofmore »« less

Authors:

Kouzuma, S ^[1]; Yamaoka, H ^[2]

School of International Liberal Studies, Chukyo University, Toyota 470-0393 (Japan)
Department of Physics, Kyushu University, Fukuoka 812-8581 (Japan)

Publication Date:: Thu Mar 01 00:00:00 EST 2012

OSTI Identifier:: 22016339

Resource Type:: Journal Article

Journal Name:: Astrophysical Journal

Additional Journal Information:: Journal Volume: 747; Journal Issue: 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); Journal ID: ISSN 0004-637X

Country of Publication:: United States

Language:: English

Subject:: 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; CATALOGS; GALAXIES; GALAXY NUCLEI; INFRARED SURVEYS; LUMINOSITY; POINT SOURCES; QUASARS; RED SHIFT; STRUCTURE FUNCTIONS

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                    Kouzuma, S, and Yamaoka, H. ENSEMBLE VARIABILITY OF NEAR-INFRARED-SELECTED ACTIVE GALACTIC NUCLEI.  United States: N. p., 2012. 
        Web.  doi:10.1088/0004-637X/747/1/14.

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                    Kouzuma, S, & Yamaoka, H. ENSEMBLE VARIABILITY OF NEAR-INFRARED-SELECTED ACTIVE GALACTIC NUCLEI.  United States.  https://doi.org/10.1088/0004-637X/747/1/14

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                    Kouzuma, S, and Yamaoka, H. 2012.  
        "ENSEMBLE VARIABILITY OF NEAR-INFRARED-SELECTED ACTIVE GALACTIC NUCLEI".  United States.  https://doi.org/10.1088/0004-637X/747/1/14.

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@article{osti_22016339,

  title        = {ENSEMBLE VARIABILITY OF NEAR-INFRARED-SELECTED ACTIVE GALACTIC NUCLEI},

  author       = {Kouzuma, S and Yamaoka, H},

  abstractNote = {We present the properties of the ensemble variability V for nearly 5000 near-infrared active galactic nuclei (AGNs) selected from the catalog of Quasars and Active Galactic Nuclei (13th Edition) and the SDSS-DR7 quasar catalog. From three near-infrared point source catalogs, namely, Two Micron All Sky Survey (2MASS), Deep Near Infrared Survey (DENIS), and UKIDSS/LAS catalogs, we extract 2MASS-DENIS and 2MASS-UKIDSS counterparts for cataloged AGNs by cross-identification between catalogs. We further select variable AGNs based on an optimal criterion for selecting the variable sources. The sample objects are divided into subsets according to whether near-infrared light originates by optical emission or by near-infrared emission in the rest frame; and we examine the correlations of the ensemble variability with the rest-frame wavelength, redshift, luminosity, and rest-frame time lag. In addition, we also examine the correlations of variability amplitude with optical variability, radio intensity, and radio-to-optical flux ratio. The rest-frame optical variability of our samples shows negative correlations with luminosity and positive correlations with rest-frame time lag (i.e., the structure function, SF), and this result is consistent with previous analyses. However, no well-known negative correlation exists between the rest-frame wavelength and optical variability. This inconsistency might be due to a biased sampling of high-redshift AGNs. Near-infrared variability in the rest frame is anticorrelated with the rest-frame wavelength, which is consistent with previous suggestions. However, correlations of near-infrared variability with luminosity and rest-frame time lag are the opposite of these correlations of the optical variability; that is, the near-infrared variability is positively correlated with luminosity but negatively correlated with the rest-frame time lag. Because these trends are qualitatively consistent with the properties of radio-loud quasars reported by some previous studies, most of our sample objects are probably radio-loud quasars. Finally, we also discuss the negative correlations seen in the near-infrared SFs.},

  doi          = {10.1088/0004-637X/747/1/14},

  url          = {https://www.osti.gov/biblio/22016339},
  journal      = {Astrophysical Journal},

  issn         = {0004-637X},

  number       = 1,

  volume       = 747,

  place        = {United States},

  year         = {Thu Mar 01 00:00:00 EST 2012},

  month        = {Thu Mar 01 00:00:00 EST 2012}

}

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