BL Lacs bright in rays |
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Authors: | A Paggi V Vittorini A Cavaliere M Tavani |
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Affiliation: | a Dipartimento di Fisica, Università di Roma Tor Vergata, Via della Ricerca Scientifica 1, I-00133 Roma, Italy;b INAF/IASF, Via Fosso del Cavaliere 1, I-00100, Roma, Italy |
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Abstract: | In this preview we consider implications from the recent AGILE γ-ray detection of the BL Lac 0716+714 in September–October 2007, marked by two intense flaring episodes reaching peak fluxes of 200×10−8 photons cm−2 s−1 in the energy range 0.1–10 GeV. The source shows no evidence of emission lines or disk radiation, related to any surrounding gas; its pure non-thermal radiation is effectively represented in terms of the synchrotron-self Compton radiation in the Thomson regime, also supported by the observed quadratic relation of the γ-ray to the X-ray flux variations. With source parameters so derived, we find a total jet power of about 4×1045 erg s−1, that makes 0716+714 one of the brightest gas-poor BL Lacs so far detected at γ-ray energies. Thus it provides an ideal benchmark to compare its intrinsic luminosity with the top power extractable from a maximally rotating black-hole via the Blandford–Znajek mechanism. With a mass close to 5×108M for the associated BH, we find the source to remain close to the Blandford–Znajek threshold during the flare. Other gas-poor but weaker BL Lacs remain well below the threshold. These findings and those expected from FERMI will provide a powerful test of GR at work. |
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Keywords: | BL Lac objects color:black" href="/science?_ob=MathURL&_method=retrieve&_udi=B6TJM-509W716-G&_mathId=mml8&_user=10&_cdi=5314&_pii=S0168900210012714&_rdoc=67&_issn=01689002&_acct=C000054348&_version=1&_userid=3837164&md5=6d661ae0aa0465f390d9f67c5fc496a6" title="Click to view the MathML source" γ" target="_blank">alt="Click to view the MathML source">γ -Ray spectra Supermassive black holes Electrodynamics |
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