The blob crashes into the mirror: modeling the exceptional γ-ray flaring activity of 3C 454.3 in 2010 November
- INAF/IASF-Roma, Via del Fosso del Cavaliere 100, I-00133 Roma (Italy)
- Universite "Tor Vergata," Via della Ricerca Scientifica 1, I-00133 Roma (Italy)
3C 454.3 is a prominent flat-spectrum radio quasar that in recent years attracted considerable attention because of its variable high-energy emissions. In this paper, we focus on the exceptional flaring activity of 3C 454.3 that was detected by AGILE and by Fermi-LAT in 2010 November. In the light of the time-varying data ranging from the radio, optical, and X-ray up to GeV γ-ray bands, we discuss a theoretical framework addressing all data in their overall evolution. For two weeks, the source has shown a plateau of enhanced GeV emission preceding a sudden major flare lasting about three days before decaying. The γ-ray flare onset is abrupt (about six hours), and is characterized by a prominent 'Compton dominance' with the GeV flux exceeding the pre-flare values by a factor of four to five. During this episode, the optical and X-ray fluxes increased by a factor of around two. Within the standard framework of a jet launched with a Lorentz bulk factor Γ ∼ 10 from a central black hole, we explore the yields of two alternatives. Case 1, with high-energy emission originating within the broad line region (BLR); and Case 2, with most of it produced outside at larger distances of a few parsecs. We show that Case 1 has considerable problems in explaining the whole set of multifrequency data. Case 2, instead, leads to a consistent and interesting interpretation based on the enhanced inverse Compton radiation that is produced as the jet crashes onto a mirror cloud positioned at parsec scales. This model explains the γ-ray versus optical/X-ray behavior of 3C 454.3, including the otherwise puzzling phenomena such as the prominent 'rphan' optical flare, and the enhanced line emission with no appreciable γ-ray counterpart that preceded the GeV γ-ray flare. It also accounts for the delayed onset of the latter on top of the long plateau. Our modeling of the exceptional 3C 454.3 γ-ray flare shows that while emission inside the canonical BLR is problematic, major and rapid variations can be produced at parsec scales with moderate bulk Lorentz factors Γ ≈ 15. Our 'crashed mirror' model is also applicable to other blazar flares marked by large Compton dominance of the emitted radiation such as the flare of PKS 1830–211 in 2010 October.
- OSTI ID:
- 22370575
- Journal Information:
- Astrophysical Journal, Vol. 793, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
- Country of Publication:
- United States
- Language:
- English
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