@article{12372dcec1af49c1a4dcf1fb42bd35a2,
title = "Multiwavelength observations of the blazar BL Lacertae: A new fast TeV γ-ray flare",
abstract = "Observations of fast TeV γ-ray flares from blazars reveal the extreme compactness of emitting regions in blazar jets. Combined with very-long-baseline radio interferometry measurements, they probe the structure and emission mechanism of the jet. We report on a fast TeV γ-ray flare from BL Lacertae observed by VERITAS, with a rise time of about 2.3 hours and a decay time of about 36 minutes. The peak flux at >200 GeV measured with the 4-minute binned light curve is (4.2 ±0.6) × 10-6 photons m-2 s-1, or ∼180% the Crab Nebula flux. Variability in GeV γ-ray, X-ray, and optical flux, as well as in optical and radio polarization was observed around the time of the TeV γ-ray flare. A possible superluminal knot was identified in the VLBA observations at 43 GHz. The flare constrains the size of the emitting region, and is consistent with several theoretical models with stationary shocks.",
author = "{VERITAS Collaboration} and Q. Feng and Jorstad, {S. G.} and Marscher, {A. P.} and Lister, {M. L.} and Kovalev, {Y. Y.} and Pushkarev, {A. B.} and T. Savolainen and I. Agudoi and Molina, {S. N.} and Gomez, {J. L.} and Larionov, {V. M.} and Borman, {G. A.} and Mokrushina, {A. A.} and Smith, {P. S.}",
note = "Funding Information: The research at Boston University was supported in part by NASA Fermi Guest Investigator Program grant NNX14AQ58G. The VLBA is an instrument of the Long Baseline Observatory (LBO). The LBO is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. The MOJAVE program is supported under NASA-Fermi grant NNX15AU76G. Data from the Steward Observatory spectropolarimetric monitoring project were used. This program is supported by Fermi Guest Investigator grants NNX15AU81G. IA acknowledges support by a Ram{\'o}n y Cajal grant of the Ministerio de Econom{\'i}a y Competitividad (MINECO) of Spain. The MAPCAT program was funded in part by MINECO through grants Funding Information: VERITAS is supported by grants from the U.S. Department of Energy Office of Science, the U.S. National Science Foundation and the Smithsonian Institution, and by NSERC in Canada. We acknowledge the excellent work of the technical support staff at the Fred Lawrence Whipple Observatory and at the collaborating institutions in the construction and operation of the instrument. The VERITAS Collaboration is grateful to Trevor Weekes for his seminal contributions and leadership in the field of VHE γ-ray astrophysics, which made this study possible. Funding Information: AYA2010-14844, AYA2013-40825-P, and AYA2016-80889-P, and by the Regional Government of Andaluc{\'i}a through grant P09-FQM-4784. Publisher Copyright: {\textcopyright} Copyright owned by the author(s) under the terms of the Creative Commons Attribution-Non Commercial-No Derivatives 4.0 International License (CC BY-NC-ND 4.0).; 35th International Cosmic Ray Conference, ICRC 2017 ; Conference date: 10-07-2017 Through 20-07-2017",
year = "2017",
language = "English (US)",
journal = "Proceedings of Science",
issn = "1824-8039",
publisher = "Sissa Medialab Srl",
}