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arXiv · 0912.2216

Powerful high energy emission of the remarkable BL Lac object S5 0716+714

V. Vittorini·M. Tavani·A. Paggi·A. Cavaliere·A. Bulgarelli·A. W. Chen·F. D'Ammando·I. Donnarumma·A. Giuliani·F. Longo·L. Pacciani·G. Pucella·S. Vercellone·A. Ferrari·S. Colafrancesco·P. Giommi
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Abstract

BL Lac objects of the intermediate subclass (IBLs) are known to emit a substantial fraction of their power in the energy range 0.1--10 GeV. Detecting gamma-ray emission from such sources provides therefore a direct probe of the emission mechanisms and of the underlying powerhouse. The AGILE gamma-ray satellite detected the remarkable IBL S5 0716+714 (z \simeq 0.3) during a high state in the period from 2007 September - October, marked by two very intense flares reaching peak fluxes of 200\times10^{-8} ph / cm^2 s above 100 MeV, with simultaneous optical and X-ray observations. We present here a theoretical model for the two major flares and discuss the overall energetics of the source. We conclude that 0716+714 is among the brightest BL Lac's ever detected at gamma-ray energies. Because of its high power and lack of signs for ongoing accretion or surrounding gas, the source is an ideal candidate to test the maximal power extractable from a rotating supermassive black hole via the pure Blandford-Znajek (BZ) mechanism. We find that during the 2007 gamma-ray flares our source approached or just exceeded the upper limit set by BZ for a black hole of mass 10^9 M_sun

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V. Vittorini, M. Tavani, A. Paggi, A. Cavaliere, A. Bulgarelli, A. W. Chen, F. D'Ammando, I. Donnarumma, A. Giuliani, F. Longo, L. Pacciani, G. Pucella, S. Vercellone, A. Ferrari, S. Colafrancesco, P. Giommi. 2009-12-11. Powerful high energy emission of the remarkable BL Lac object S5 0716+714. https://doi.org/10.1088/0004-637x%2F706%2F2%2F1433

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