Particle-acceleration time-scales in TeV blazar flares |
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Authors: | Joni Tammi Peter Duffy |
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Affiliation: | UCD School of Physics, University College Dublin, Belfield, Dublin 4, Ireland |
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Abstract: | Observations of minute-scale flares in TeV Blazars place constraints on particle-acceleration mechanisms in those objects. The implications for a variety of radiation mechanisms have been addressed in the literature; in this paper, we compare four different acceleration mechanisms: diffusive shock acceleration, second-order Fermi, shear acceleration and the converter mechanism. When the acceleration time-scales and radiative losses are taken into account, we can exclude shear acceleration and the neutron-based converted mechanism as possible acceleration processes in these systems. The first-order Fermi process and the converter mechanism working via synchrotron self-Compton (SSC) photons are still practically instantaneous, however, provided sufficient turbulence is generated on the time-scale of seconds. We propose stochastic acceleration as a promising candidate for the energy-dependent time delays in recent gamma-ray flares of Markarian 501. |
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Keywords: | acceleration of particles galaxies: active BL Lacertae objects: general galaxies: jets |
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