Understanding extreme quasar optical variability with CRTS - I. Major AGN flares

作者：Graham Matthew J; Djorgovski S G; Drake Andrew J; Stern Daniel; Mahabal Ashish A; Glikman Eilat; Larson Steve; Christensen Eric

来源：Monthly Notices of the Royal Astronomical Society, 2017, 470(4): 4112-4132.

DOI：10.1093/mnras/stx1456

• methods: data analysis
• techniques: photometric
• surveys
• quasars: general

There 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.

• 出版日期2017-10