Investigation of the Gamma-ray Spectrum of CTA 102 During the Exceptional Flaring State in 2016-2017. (arXiv:1911.12087v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Sahakyan_N/0/1/0/all/0/1">N. Sahakyan</a>
The flat spectrum radio quasar CTA 102 entered an extended period of activity
from 2016 to 2017 during which several strong $gamma$-ray flares were
observed. Using Fermi large area telescope data a detailed investigation of
gray spectra of CTA 102 during the flaring period is performed. In several
periods the gray spectrum is not consistent with a simple power-law, having a
hard photon index with an index of $sim(1.8-2.0)$ that shows a spectral cutoff
around an observed photon energy of $sim(9-16)$ GeV. The internal $gamma$-ray
absorption via photon-photon pair production on the broad-line-region-reflected
photons cannot account for the observed cut-off/break even if the emitting
region is very close to the central source. This cut-off/break is likely due to
a similar intrinsic break in the energy distribution of emitting particles. The
origin of the spectral break is investigated through the multiwavelength
modeling of the spectral energy distribution, considering a different location
for the emitting region. The observed X-ray and $gamma$-ray data is modeled as
inverse Compton scattering of synchrotron and/or external photons on the
electron population that produce the radio-to-optical emission which allowed to
constrain the power-law index and cut-off energy in the electron energy
distribution. The obtained results are discussed in the context of a diffusive
acceleration of electrons in the CTA 102 jet.
The flat spectrum radio quasar CTA 102 entered an extended period of activity
from 2016 to 2017 during which several strong $gamma$-ray flares were
observed. Using Fermi large area telescope data a detailed investigation of
gray spectra of CTA 102 during the flaring period is performed. In several
periods the gray spectrum is not consistent with a simple power-law, having a
hard photon index with an index of $sim(1.8-2.0)$ that shows a spectral cutoff
around an observed photon energy of $sim(9-16)$ GeV. The internal $gamma$-ray
absorption via photon-photon pair production on the broad-line-region-reflected
photons cannot account for the observed cut-off/break even if the emitting
region is very close to the central source. This cut-off/break is likely due to
a similar intrinsic break in the energy distribution of emitting particles. The
origin of the spectral break is investigated through the multiwavelength
modeling of the spectral energy distribution, considering a different location
for the emitting region. The observed X-ray and $gamma$-ray data is modeled as
inverse Compton scattering of synchrotron and/or external photons on the
electron population that produce the radio-to-optical emission which allowed to
constrain the power-law index and cut-off energy in the electron energy
distribution. The obtained results are discussed in the context of a diffusive
acceleration of electrons in the CTA 102 jet.
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