The Impact of Plasma Instabilities on the Spectra of TeV Blazars. (arXiv:1904.13345v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Batista_R/0/1/0/all/0/1">Rafael Alves Batista</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Saveliev_A/0/1/0/all/0/1">Andrey Saveliev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pino_E/0/1/0/all/0/1">Elisabete M. de Gouveia Dal Pino</a>
Relativistic jets from blazars are known to be sources of very-high-energy
gamma rays (VHEGRs). During their propagation in the intergalactic space,
VHEGRs interact with pervasive cosmological photon fields such as the
extragalactic background light (EBL) and the cosmic microwave background (CMB),
producing electron-positron pairs. These pairs can upscatter CMB/EBL photons to
high energies via inverse Compton scattering, thereby continuing the cascade
process. This is often used to set limits on intergalactic magnetic fields
(IGMFs). However, the picture may change if plasma instabilities, arising due
to the interaction of the pairs with the intergalactic medium (IGM), cool down
the electrons/positrons faster than inverse Compton scattering. As a
consequence, the kinetic energy lost by the pairs to the IGM could cause a
hardening in the observed gamma-ray spectrum at energies below $sim$100 GeV.
Here we study several types and models of instabilities and assess their impact
for interpreting observations of distant blazars. Our results suggest that
plasma instabilities can describe the spectra of some blazars and mimic the
effects of IGMFs, depending on parameters such as intrinsic spectrum of the
object, the density and temperature of the IGM, and the luminosity of the beam.
Relativistic jets from blazars are known to be sources of very-high-energy
gamma rays (VHEGRs). During their propagation in the intergalactic space,
VHEGRs interact with pervasive cosmological photon fields such as the
extragalactic background light (EBL) and the cosmic microwave background (CMB),
producing electron-positron pairs. These pairs can upscatter CMB/EBL photons to
high energies via inverse Compton scattering, thereby continuing the cascade
process. This is often used to set limits on intergalactic magnetic fields
(IGMFs). However, the picture may change if plasma instabilities, arising due
to the interaction of the pairs with the intergalactic medium (IGM), cool down
the electrons/positrons faster than inverse Compton scattering. As a
consequence, the kinetic energy lost by the pairs to the IGM could cause a
hardening in the observed gamma-ray spectrum at energies below $sim$100 GeV.
Here we study several types and models of instabilities and assess their impact
for interpreting observations of distant blazars. Our results suggest that
plasma instabilities can describe the spectra of some blazars and mimic the
effects of IGMFs, depending on parameters such as intrinsic spectrum of the
object, the density and temperature of the IGM, and the luminosity of the beam.
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