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arXiv · 1605.00571

The GeV counterpart of VER J2019+407 in the northern shell of the supernova remnant G78.2+2.1 ($\gamma$ Cygni)

Nissim Fraija·Miguel Araya
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Abstract

Analysis of gamma-ray emission from the supernova remnant G78.2+2.1 ($\gamma$ Cygni) with 7.2 years of cumulative data from the Fermi-LAT telescope shows a distinct hard, bright and extended component to the north of the shell coincident with the known TeV source VER J2019+407. In the GeV-TeV energy range its spectrum is best described by a broken power-law with indices 1.8 below a break energy of 71 GeV and 2.5 above the break. A broadband spectral energy distribution is assembled and different scenarios for the origin of the gamma-rays are explored. Both hadronic and leptonic mechanisms are able to account for the GeV-TeV observations. In the leptonic framework, a superposition of inverse Compton and nonthermal bremsstrahlung emissions is needed whereas the hadronic scenario requires a cosmic ray population described by a broken power-law distribution with a relatively hard spectral index of $\sim1.8$ below a break particle energy of 0.45 TeV. In addition, the neutrino flux expected from cosmic ray interactions is calculated.

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Nissim Fraija, Miguel Araya. 2016-05-02. The GeV counterpart of VER J2019+407 in the northern shell of the supernova remnant G78.2+2.1 ($\gamma$ Cygni). https://doi.org/10.3847/0004-637x%2F826%2F1%2F31

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