Understanding extreme quasar optical variability with CRTS – I. Major AGN flares
AuthorGraham, Matthew J.
Djorgovski, S. G.
Drake, Andrew J.
Mahabal, Ashish A.
AffiliationUniv Arizona, Dept Planetary Sci, Lunar & Planetary Lab
MetadataShow full item record
PublisherOXFORD UNIV PRESS
CitationUnderstanding extreme quasar optical variability with CRTS – I. Major AGN flares 2017, 470 (4):4112 Monthly Notices of the Royal Astronomical Society
Rights© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
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AbstractThere is a large degree of variety in the optical variability of quasars and it is unclear whether this is all attributable to a single (set of) physical mechanism(s). We present the results of a systematic search for major flares in active galactic nucleus (AGN) in the Catalina Real-time Transient Survey as part of a broader study into extreme quasar variability. Such flares are defined in a quantitative manner as being atop of the normal, stochastic variability of quasars. We have identified 51 events from over 900 000 known quasars and high-probability quasar candidates, typically lasting 900 d and with a median peak amplitude of Delta m = 1.25 mag. Characterizing the flare profile with a Weibull distribution, we find that nine of the sources are well described by a single-point single-lens model. This supports the proposal by Lawrence et al. that microlensing is a plausible physical mechanism for extreme variability. However, we attribute the majority of our events to explosive stellar-related activity in the accretion disc: superluminous supernovae, tidal disruption events and mergers of stellar mass black holes.
VersionFinal published version
SponsorsNSF [AST-1413600, AST-1518308]; Alfred P. Sloan Foundation; National Science Foundation; U.S. Department of Energy Office of Science; NASA