12-20 July 2017
Asia/Seoul timezone
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BEXCO - Room E(106/107)

[GA083] MWL Observations of the Blazar BL Lacertae: a new fast TeV gamma-ray flare


  • Qi FENG

Primary authors



The detections of fast TeV gamma-ray flares from blazars since the late 1990s have made substantial contributions to advance our understanding of these objects. These extreme flares have posed challenges to blazar models, and led to the development of new models (e.g. localized regions of magnetic reconnection, and plasma passing a standing shock). However, there are only a handful of such flares detected to date, and only over the last few years from low-frequency peaked BL Lac objects and flat spectrum radio quasars. We report on a fast TeV gamma-ray flare from BL Lacertae observed by VERITAS in 2016 October, reaching a peak flux of ~180% the Crab Nebula flux, as measured with the 4-minute binned light curve at >200 GeV. The observed flare presents an unusual asymmetric shape with a rising timescale of about 2.3 hours and a decay timescale of about 36 minutes. Multi-wavelength observations around the time of the TeV gamma-ray flare is presented, including optical and VLBA radio polarization measurements. The interpretations of the flare including the constraints on the size of the emitting region and several scenarios consistent with the data is discussed.