A1 Refereed original research article in a scientific journal
RAPID TeV GAMMA-RAY FLARING OF BL LACERTAE
Authors: Arlen T, Aune T, Beilicke M, Benbow W, Bouvier A, Buckley JH, Bugaev V, Cesarini A, Ciupik L, Connolly MP, Cui W, Dickherber R, Dumm J, Errando M, Falcone A, Federici S, Feng Q, Finley JP, Finnegan G, Fortson L, Furniss A, Galante N, Gall D, Griffin S, Grube J, Gyuk G, Hanna D, Holder J, Humensky TB, Kaaret P, Karlsson N, Kertzman M, Khassen Y, Kieda D, Krawczynski H, Krennrich F, Maier G, Moriarty P, Mukherjee R, Nelson T, de Bhroithe AO, Ong RA, Orr M, Park N, Perkins JS, Pichel A, Pohl M, Prokoph H, Quinn J, Ragan K, Reyes LC, Reynolds PT, Roache E, Saxon DB, Schroedter M, Sembroski GH, Staszak D, Telezhinsky I, Tesic G, Theiling M, Tsurusaki K, Varlotta A, Vincent S, Wakely SP, Weekes TC, Weinstein A, Welsing R, Williams DA, Zitzer B, Jorstad SG, MacDonald NR, Marscher AP, Smith PS, Walker RC, Hovatta T, Richards J, Max-Moerbeck W, Readhead A, Lister ML, Kovalev YY, Pushkarev AB, Gurwell MA, Lahteenmaki A, Nieppola E, Tornikoski M, Jarvela E
Publisher: IOP PUBLISHING LTD
Publication year: 2013
Journal: Astrophysical Journal
Journal name in source: ASTROPHYSICAL JOURNAL
Journal acronym: ASTROPHYS J
Article number: ARTN 92
Number in series: 2
Volume: 762
Issue: 2
Number of pages: 13
ISSN: 0004-637X
DOI: https://doi.org/10.1088/0004-637X/762/2/92
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 +/- 0.6) x 10(-6) photons m(-2) 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 +/- 4 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 +/- 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 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.
