MAGICal GRB 190114C: Cutoff in the spectrum at sub-GeV energies. (arXiv:1905.11844v1 [astro-ph.HE])

MAGICal GRB 190114C: Cutoff in the spectrum at sub-GeV energies. (arXiv:1905.11844v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Chand_V/0/1/0/all/0/1">Vikas Chand</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Pal_P/0/1/0/all/0/1">Partha Sarathi Pal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Banerjee_A/0/1/0/all/0/1">Ankush Banerjee</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Sharma_V/0/1/0/all/0/1">Vidushi Sharma</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tam_P/0/1/0/all/0/1">P. H. T. Tam</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+He_X/0/1/0/all/0/1">Xinbo He</a>

GRB 190114C is a famous Gamma-Ray Burst (GRB) due to its detection at sub-TeV
energies by MAGIC, seen at redshift z = 0.42. This burst is one of the
brightest GRB detected by fermi. We present a detailed analysis of GRB 190114C
prompt emission, using the two fermi detectors: GBM and LAT. The emph{LAT low
energy events} (LLE) data is also considered. A joint GBM-LAT analysis reveals
a sub-$GeV$ spectral cutoff. A similar high energy cutoff was reported in GRB
160509A and GRB 100724B earlier, and a handful of other sources. The cutoff can
be explained by the intrinsic opacity due to pair production within the
emitting region. Such morphology in these GRBs suggests that they belong to one
specific class having a similar source of the radiation mechanism. GRB 190114C
shows a transition from non-thermal to a quasi-thermal-like spectrum along with
radiation due to external shock. From spectrum analysis and $Lorentz$ factor
evolution from the trigger time to late emission, considering the fact that
sub-TeV photons are detected in MAGIC, we are able to draw an emission
mechanism picture, where the prompt emission spectrum is more consistent with
spectrum via photospheric dissipation with presence of external shock emission
simultaneously.

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