Rapid TeV Gamma-Ray Flaring of BL Lacertae
Creators: name: Arlen, T.
name: Aune, T.
name: Beilicke, M.
name: Benbow, W.
name: Bouvier, A.
name: Buckley, J. H.
name: Bugaev, V.
name: Cesarini, A.
name: Ciupik, L.
name: Connolly, M. P.
name: Cui, W.
name: Dickherber, R.
name: Dumm, J.
name: Errando, M.
name: Falcone, A.
name: Federici, S.
name: Feng, Q.
name: Finley, J. P.
name: Finnegan, G.
name: Fortson, L.
name: Furniss, A.
name: Galante, N.
name: Gall, D.
name: Griffin, S.
name: Grube, J.
name: Gyuk, G.
name: Hanna, D.
name: Holder, J.
name: Humensky, T. B.
name: Kaaret, P.
name: Karlsson, N.
name: Kertzman, M.
name: Khassen, Y.
name: Kieda, D.
name: Krawczynski, H.
name: Krennrich, F.
name: Maier, G.
name: Moriarty, P.
name: Mukherjee, R.
name: Nelson, T.
name: de Bhroithe, A. O'Faolain
name: Ong, R. A.
name: Orr, M.
name: Park, N.
name: Perkins, J. S.
name: Pichel, A.
name: Pohl, M.
name: Prokoph, H.
name: Quinn, J.
name: Ragan, K.
name: Reyes, L. C.
name: Reynolds, P. T.
name: Roache, E.
name: Saxon, D. B.
name: Schroedter, M.
name: Sembroski, G. H.
name: Staszak, D.
name: Telezhinsky, I.
name: Tesic, G.
name: Theiling, M.
name: Tsurusaki, K.
name: Varlotta, A.
name: Vincent, S.
name: Wakely, S. P.
name: Weekes, T. C.
name: Weinstein, A.
name: Welsing, R.
name: Williams, D. A.
name: Zitzer, B.
name: Jorstad, S. G.
name: MacDonald, N. R.
name: Marscher, A. P.
name: Smith, P. S.
name: Walker, R. C.
name: Hovatta, T.
name: Richards, J.
name: Max-Moerbeck, W.
name: Readhead, A.
name: Lister, M. L.
name: Kovalev, Y. Y.
name: Pushkarev, A. B.
name: Gurwell, M. A.
name: Lahteenmaki, A.
name: Nieppola, E.
name: Tornikoski, M.
name: Jarvela, E.
Publisher: name: arXiv
Year: 2012
Subjects: subject: High Energy Astrophysical Phenomena (astro-ph.HE)
subject: FOS: Physical sciences
subject: FOS: Physical sciences

description: We report on the detection of a very rapid TeV gamma-ray flare from BL Lacertae on 2011 June 28 with the Very Energetic Radiation Imaging Telescope Array System (VERITAS). The flaring activity was observed during a 34.6-minute exposure, when the integral flux above 200 GeV reached $(3.4\pm0.6) \times 10^{-6} \;\text{photons}\;\text{m}^{-2}\text{s}^{-1}$, roughly 125% of the Crab Nebula flux measured by VERITAS. The light curve indicates that the observations missed the rising phase of the flare but covered a significant portion of the decaying phase. The exponential decay time was determined to be $13\pm4$ minutes, making it one of the most rapid gamma-ray flares seen from a TeV blazar. The gamma-ray spectrum of BL Lacertae during the flare was soft, with a photon index of $3.6\pm 0.4$, which is in agreement with the measurement made previously by MAGIC in a lower flaring state. Contemporaneous radio observations of the source with the Very Long Baseline Array (VLBA) revealed the emergence of a new, superluminal component from the core around the time of the TeV gamma-ray flare, accompanied by changes in the optical polarization angle. Changes in flux also appear to have occurred at optical, UV, and GeV gamma-ray wavelengths at the time of the flare, although they are difficult to quantify precisely due to sparse coverage. A strong flare was seen at radio wavelengths roughly four months later, which might be related to the gamma-ray flaring activities. We discuss the implications of these multiwavelength results.
description: Accepted for publication in The Astrophysical Journal