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Title: The Ensemble Photometric Variability of Over 10 5 Quasars in the Dark Energy Camera Legacy Survey and the Sloan Digital Sky Survey

Abstract

We present the ensemble variability analysis results of quasars using the Dark Energy Camera Legacy Survey (DECaLS) and the Sloan Digital Sky Survey (SDSS) quasar catalogs. Our data set includes 119,305 quasars with redshifts up to 4.89. Combining the two data sets provides a 15 year baseline and permits the analysis of the long timescale variability. Adopting a power-law form for the variability structure function, $V=A(t/$1years)$^γ$, we use the multidimensional parametric fitting to explore the relationships between the quasar variability amplitude and a wide variety of quasar properties, including redshift (positive), bolometric luminosity (negative), rest-frame wavelength (negative), and black hole mass (uncertain). We also find that γ can be also expressed as a function of redshift (negative), bolometric luminosity (positive), rest-frame wavelength (positive), and black hole mass (positive). Tests of the fitting significance with the bootstrap method show that, even with such a large quasar sample, some correlations are marginally significant. The typical value of $γ$ for the entire data set is $≳0.25$, consistent with the results in previous studies on both the quasar ensemble variability and the structure function. A significantly negative correlation between the variability amplitude and the Eddington ratio is found, which may be explained as anmore » effect of accretion disk instability.« less

Authors:
 [1]; ORCiD logo [2]; ORCiD logo [3]; ORCiD logo [4]; ORCiD logo [5]
  1. Peking Univ., Beijing (China). School of Physics, Dept. of Astronomy
  2. Univ. of Arizona, Tucson, AZ (United States)
  3. Peking Univ., Beijing (China). School of Physics, Dept. of Astronomy and Kavli Inst. for Astronomy and Astrophysics
  4. Univ. of Arizona, Tucson, AZ (United States); Peking Univ., Beijing (China). Kavli Inst. for Astronomy and Astrophysics
  5. Peking Univ., Beijing (China). Kavli Inst. for Astronomy and Astrophysics; Peking Univ., Beijing (China). School of Physics, Dept. of Astronomy
Publication Date:
Research Org.:
Lawrence Berkeley National Laboratory (LBNL), Berkeley, CA (United States). National Energy Research Scientific Computing Center (NERSC)
Sponsoring Org.:
USDOE
OSTI Identifier:
1544064
Resource Type:
Accepted Manuscript
Journal Name:
The Astrophysical Journal (Online)
Additional Journal Information:
Journal Name: The Astrophysical Journal (Online); Journal Volume: 861; Journal Issue: 1; Journal ID: ISSN 1538-4357
Publisher:
Institute of Physics (IOP)
Country of Publication:
United States
Language:
English
Subject:
79 ASTRONOMY AND ASTROPHYSICS; Astronomy & Astrophysics

Citation Formats

Li, Zefeng, McGreer, Ian D., Wu, Xue-Bing, Fan, Xiaohui, and Yang, Qian. The Ensemble Photometric Variability of Over 105 Quasars in the Dark Energy Camera Legacy Survey and the Sloan Digital Sky Survey. United States: N. p., 2018. Web. doi:10.3847/1538-4357/aac6ce.
Li, Zefeng, McGreer, Ian D., Wu, Xue-Bing, Fan, Xiaohui, & Yang, Qian. The Ensemble Photometric Variability of Over 105 Quasars in the Dark Energy Camera Legacy Survey and the Sloan Digital Sky Survey. United States. doi:10.3847/1538-4357/aac6ce.
Li, Zefeng, McGreer, Ian D., Wu, Xue-Bing, Fan, Xiaohui, and Yang, Qian. Tue . "The Ensemble Photometric Variability of Over 105 Quasars in the Dark Energy Camera Legacy Survey and the Sloan Digital Sky Survey". United States. doi:10.3847/1538-4357/aac6ce. https://www.osti.gov/servlets/purl/1544064.
@article{osti_1544064,
title = {The Ensemble Photometric Variability of Over 105 Quasars in the Dark Energy Camera Legacy Survey and the Sloan Digital Sky Survey},
author = {Li, Zefeng and McGreer, Ian D. and Wu, Xue-Bing and Fan, Xiaohui and Yang, Qian},
abstractNote = {We present the ensemble variability analysis results of quasars using the Dark Energy Camera Legacy Survey (DECaLS) and the Sloan Digital Sky Survey (SDSS) quasar catalogs. Our data set includes 119,305 quasars with redshifts up to 4.89. Combining the two data sets provides a 15 year baseline and permits the analysis of the long timescale variability. Adopting a power-law form for the variability structure function, $V=A(t/$1years)$^γ$, we use the multidimensional parametric fitting to explore the relationships between the quasar variability amplitude and a wide variety of quasar properties, including redshift (positive), bolometric luminosity (negative), rest-frame wavelength (negative), and black hole mass (uncertain). We also find that γ can be also expressed as a function of redshift (negative), bolometric luminosity (positive), rest-frame wavelength (positive), and black hole mass (positive). Tests of the fitting significance with the bootstrap method show that, even with such a large quasar sample, some correlations are marginally significant. The typical value of $γ$ for the entire data set is $≳0.25$, consistent with the results in previous studies on both the quasar ensemble variability and the structure function. A significantly negative correlation between the variability amplitude and the Eddington ratio is found, which may be explained as an effect of accretion disk instability.},
doi = {10.3847/1538-4357/aac6ce},
journal = {The Astrophysical Journal (Online)},
number = 1,
volume = 861,
place = {United States},
year = {2018},
month = {6}
}

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