TY - JOUR
T1 - The Ensemble Photometric Variability of over 105 Quasars in the Dark Energy Camera Legacy Survey and the Sloan Digital Sky Survey
AU - Li, Zefeng
AU - McGreer, Ian D.
AU - Wu, Xue Bing
AU - Fan, Xiaohui
AU - Yang, Qian
N1 - Funding Information:
We thank the support from NSFC under grant Nos. 11373008 and 11533001, from the National Key Basic Research Program of China under grant 2014CB845700, and from the Ministry of Science and Technology of China under grant 2016YFA0400703. We thank Fuyan Bian, Jinyi Shangguan, Wenwen Zuo, Jinyi Yang, Feige Wang, and Bingxu Yao for helping in revising it. We also acknowledge Christian Wolf, Szymon Kozłowski, Matthew A. Malkan, Robert J. Brunner, and Donald G. York for helpful discussions.
Publisher Copyright:
© 2018. The American Astronomical Society. All rights reserved.
PY - 2018/7/1
Y1 - 2018/7/1
N2 - 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, , 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.
AB - 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, , 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.
KW - galaxies: active
KW - galaxies: nuclei
KW - quasars: general
KW - techniques: photometric
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U2 - 10.3847/1538-4357/aac6ce
DO - 10.3847/1538-4357/aac6ce
M3 - Article
AN - SCOPUS:85049926633
VL - 861
JO - Astrophysical Journal
JF - Astrophysical Journal
SN - 0004-637X
IS - 1
M1 - 6
ER -