Multiwavelength Observations of the Blazar BL Lacertae: A New Fast TeV Gamma-Ray Flare
Multiwavelength Observations of the Blazar BL Lacertae: A New Fast TeV Gamma-Ray Flare
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DOI：
10.3847/1538-4357/aab35c
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发表时间：
2018-02
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通讯作者：
A. Abeysekara;W. Benbow;R. Bird;T. Brantseg;R. Brose;M. Buchovecky;J. Buckley;V. Bugaev;M. Connolly;W. Cui;W. Cui;M. Daniel;A. Falcone;Q. Feng;Q. Feng;J. Finley;L. Fortson;A. Furniss;G. Gillanders;I. Gunawardhana;M. Hütten;D. Hanna;O. Hervet;J. Holder;G. Hughes;T. Humensky;C. Johnson;P. Kaaret;P. Kar;M. Kertzman;F. Krennrich;M. Lang;T. T. Lin-T.;S. McArthur;P. Moriarty;R. Mukherjee;S. O’Brien;R. Ong;A. Otte;N. Park;A. Petrashyk;M. Pohl;E. Pueschel;J. Quinn;K. Ragan;P. Reynolds;G. Richards;E. Roache;C. Rulten;I. Sadeh;M. Santander;M. Santander;G. Sembroski;K. Shahinyan;S. Wakely;A. Weinstein;R. Wells;P. Wilcox;D. Williams;B. Zitzer;S. Jorstad;S. Jorstad;A. Marscher;M. Lister;Y. Kovalev;Y. Kovalev;A. Pushkarev;T. Savolainen;T. Savolainen;I. Agudo;S. Molina;J. Gómez;V. Larionov;G. Borman;A. Mokrushina;M. Tornikoski;A. Lähteenmäki;A. Lähteenmäki;W. Chamani;S. Enestam;S. Kiehlmann;T. Hovatta;Paul S. Smith;P. Pontrelli
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作者：
A. Abeysekara;W. Benbow;R. Bird;T. Brantseg;R. Brose;M. Buchovecky;J. Buckley;V. Bugaev;M. Connolly;W. Cui;W. Cui;M. Daniel;A. Falcone;Q. Feng;Q. Feng;J. Finley;L. Fortson;A. Furniss;G. Gillanders;I. Gunawardhana;M. Hütten;D. Hanna;O. Hervet;J. Holder;G. Hughes;T. Humensky;C. Johnson;P. Kaaret;P. Kar;M. Kertzman;F. Krennrich;M. Lang;T. T. Lin-T.;S. McArthur;P. Moriarty;R. Mukherjee;S. O’Brien;R. Ong;A. Otte;N. Park;A. Petrashyk;M. Pohl;E. Pueschel;J. Quinn;K. Ragan;P. Reynolds;G. Richards;E. Roache;C. Rulten;I. Sadeh;M. Santander;M. Santander;G. Sembroski;K. Shahinyan;S. Wakely;A. Weinstein;R. Wells;P. Wilcox;D. Williams;B. Zitzer;S. Jorstad;S. Jorstad;A. Marscher;M. Lister;Y. Kovalev;Y. Kovalev;A. Pushkarev;T. Savolainen;T. Savolainen;I. Agudo;S. Molina;J. Gómez;V. Larionov;G. Borman;A. Mokrushina;M. Tornikoski;A. Lähteenmäki;A. Lähteenmäki;W. Chamani;S. Enestam;S. Kiehlmann;T. Hovatta;Paul S. Smith;P. Pontrelli
结合超长基线干涉测量法的测量，快速TeV伽玛射线耀斑的观测探测了耀变体喷流的结构和发射机制。然而，到目前为止，只有少数这样的耀斑被探测到，而且只是在最近几年里，这些耀斑才在低频峰值的BL Lac天体和平谱射电类星体上被观测到。我们报告了由高能辐射成像望远镜阵列系统（VERITAS）观测到的一个快速TeV伽玛射线耀斑。上升时间为~ 2.3小时，衰减时间为~ 36分钟。在200 GeV以上的峰值通量为（4.2±0.6）× 10−6光子m−2 s−1，对应于在相同能量阈值以上从蟹状星云观测到的通量的180%。与TeV伽玛射线耀斑同时发生的变异性在GeV伽玛射线、x射线和光通量以及光学和射电极化中被观测到。此外，在43 GHz的甚长基线阵列观测中发现了一个可能具有超光速表观速度的移动发射特征，可能在伽马射线耀斑发生时通过喷流的射电核心。我们讨论了对耀斑发射区域的大小、洛伦兹因子和位置的限制，以及几种理论模型的解释，这些模型调用了通过静止冲击的相对论性等离子体。
Combined with measurements made by very-long-baseline interferometry, the observations of fast TeV gamma-ray flares probe the structure and emission mechanism of blazar jets. However, only a handful of such flares have been detected to date, and only within the last few years have these flares been observed from lower-frequency-peaked BL Lac objects and flat-spectrum radio quasars. We report on a fast TeV gamma-ray flare from the blazar BL Lacertae observed by the Very Energetic Radiation Imaging Telescope Array System (VERITAS). with a rise time of ∼2.3 hr and a decay time of ∼36 min. The peak flux above 200 GeV is (4.2 ± 0.6) × 10−6 photon m−2 s−1 measured with a 4-minute-binned light curve, corresponding to ∼180% of the flux that is observed from the Crab Nebula above the same energy threshold. Variability contemporaneous with the TeV gamma-ray flare was observed in GeV gamma-ray, X-ray, and optical flux, as well as in optical and radio polarization. Additionally, a possible moving emission feature with superluminal apparent velocity was identified in Very Long Baseline Array observations at 43 GHz, potentially passing the radio core of the jet around the time of the gamma-ray flare. We discuss the constraints on the size, Lorentz factor, and location of the emitting region of the flare, and the interpretations with several theoretical models that invoke relativistic plasma passing stationary shocks.