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Correlation between optical and UV variability of a large sample of quasars

Xin, Chengcheng and Charisi, Maria and Haiman, Zoltán and Schiminovich, David (2020) Correlation between optical and UV variability of a large sample of quasars. Monthly Notices of the Royal Astronomical Society, 495 (1). pp. 1403-1413. ISSN 0035-8711. doi:10.1093/mnras/staa1258.

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The variability of quasars across multiple wavelengths is a useful probe of physical conditions in active galactic nuclei. In particular, variable accretion rates, instabilities, and reverberation effects in the accretion disc of a supermassive black hole are expected to produce correlated flux variations in ultraviolet (UV) and optical bands. Recent work has further argued that binary quasars should exhibit strongly correlated UV and optical periodicities. Strong UV–optical correlations have indeed been established in small samples of (N ≲ 30) quasars with well-sampled light curves, and have extended the ‘bluer-when-brighter’ trend previously found within the optical bands. Here, we further test the nature of quasar variability by examining the observed-frame UV–optical correlations among bright quasars extracted from the Half Million Quasars (HMQ) catalogue. We identified a large sample of 1315 quasars in HMQ with overlapping UV and optical light curves from the Galaxy Evolution Explorer and the Catalina Real-time Transient Survey, respectively. We find that strong correlations exist in this much larger sample, but we rule out, at ∼95 per cent confidence, the simple hypothesis that the intrinsic UV and optical variations of all quasars are fully correlated. Our results therefore imply the existence of physical mechanism(s) that can generate uncorrelated optical and UV flux variations.

Item Type:Article
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URLURL TypeDescription Paper
Charisi, Maria0000-0003-3579-2522
Haiman, Zoltán0000-0003-3633-5403
Alternate Title:Correlation between Optical and UV Variability of Quasars
Additional Information:© 2020 The Author(s). Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model ( Accepted 2020 April 6. Received 2020 April 1; in original form 2020 January 9. We thank Suvi Gezari for helpful discussions, Rick Edelson for providing the Swift light curves, and the anonymous referee for useful comments that improved this manuscript. We acknowledge support from NASA through Astrophysics Data Analysis Program (ADAP) grant 80NSSC18K1093 (to ZH and DS) and through Swift grant 80NSSC19K0149 (ZH and MC), and from the National Science Foundation (NSF) through AST grant1715661 (ZH) and through the North American Nano-hertz Observatory for Gravitational Waves (NANOGrav) Physics Frontier Center, award number 1430284 (MC). The CSS survey is funded by the National Aeronautics and Space Administration under Grant No. NNG05GF22G issued through the Science Mission Directorate Near-Earth Objects Observations Program. The CRTS survey is supported by the U.S. National Science Foundation under grants AST-0909182 and AST-1313422.
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Subject Keywords:galaxies: active, quasars: general
Issue or Number:1
Record Number:CaltechAUTHORS:20200625-112849319
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Official Citation:Chengcheng Xin, Maria Charisi, Zoltán Haiman, David Schiminovich, Correlation between optical and UV variability of a large sample of quasars, Monthly Notices of the Royal Astronomical Society, Volume 495, Issue 1, June 2020, Pages 1403–1413,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:104044
Deposited By: George Porter
Deposited On:26 Jun 2020 14:07
Last Modified:16 Nov 2021 18:27

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