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Issue A&A
Volume 371, Number 1, May III 2001
Page(s) 61 - 67
Section Extragalactic astronomy
DOI http://dx.doi.org/10.1051/0004-6361:20010308



A&A 371, 61-67 (2001)
DOI: 10.1051/0004-6361:20010308

On the hadronic beam model of TeV $\mathsf{\gamma}$-ray flares from blazars

D. Purmohammad1 and J. Samimi1, 2

1  Department of Physics, Sharif University of Technology, PO Box 11365-9161, Tehran, Iran
    e-mail: dpu@mehr.sharif.ac.ir
2  Center for Theoretical Physics and Mathematics, PO Box 11365-8486, Tehran, Iran

(Received 5 July 2000 / Accepted 5 February 2001)

Abstract
We propose two models, based on the hadronic beam-cloud collision, for production of TeV $\gamma$-ray flares in blazars. In the first model, a change in bulk Lorentz factor of the jet of the Active Galactic Nucleus (AGN) produces the flare. In the second model we consider a two-stage mechanism for high-energy particle acceleration in the jet. This system produces a power law spectrum with two different power indices at low and high energies, which is more efficient than one-stage shock acceleration at high energies. Using this spectrum in a hadronic beam-cloud model for $\gamma$-ray emission of blazars, a variable TeV as well as a stable GeV $\gamma$-ray flux is predicted. The break energy in the spectrum, related to distance between the jet base and terminal shock or boundary layer thickness, is the parameter used to obtain TeV flares.


Key words: gamma rays: theory -- galaxies: jets -- Bl Lacertae objects: individual: Mrk 421 -- acceleration of particles

Offprint request: J. Samimi, samimi@physics.sharif.ac.ir

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