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arXiv · 1509.04046

The high-energy gamma-ray detection of G73.9+0.9, a supernova remnant interacting with a molecular cloud

Andrzej A. Zdziarski·Denys Malyshev·Emma de Ona Wilhelmi·Giovanna Pedaletti·Ruizhi Yang·Maria Chernyakova·Marcos Lopez-Caniego·Joanna Mikolajewska·Rupal Basak
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Abstract

We have analysed the Fermi LAT data on the SNR G73.9+0.9. We have confirmed a previous detection of high-energy gamma-rays from this source at a high significance of $\simeq 12\sigma$. The observed spectrum shows a significant curvature, peaking in $E F_E$ at $\sim$1 GeV. We have also calculated the flux upper limits in the mm-wavelength and X-ray ranges from Planck and XMM-Newton, respectively. We have inspected the intensity of the CO (1$\rightarrow $0) emission line and found a large peak at a velocity range corresponding to the previously estimated source distance of $\sim$4 kpc, which may indicate an association between a molecular cloud and the SNR. The gamma-ray emission appears due to interaction of accelerated particles within the SNR with the matter of the cloud. The most likely radiative process responsible for the gamma-ray emission is decay of neutral pions produced in ion-ion collisions. While a dominant leptonic origin of this emission can be ruled out, the relativistic electron population related to the observed radio flux will necessarily lead to a certain level of bremsstrahlung gamma-ray emission. Based on this broad-band modelling, we have developed a method to estimate the magnetic field, yielding $B\geq 80\,\mu$G at our best estimate of the molecular cloud density (or less at a lower density). G73.9+0.9 appears similar, though somewhat weaker, to other SNRs interacting with a local dense medium detected by the LAT.

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Andrzej A. Zdziarski, Denys Malyshev, Emma de Ona Wilhelmi, Giovanna Pedaletti, Ruizhi Yang, Maria Chernyakova, Marcos Lopez-Caniego, Joanna Mikolajewska, Rupal Basak. 2015-09-14. The high-energy gamma-ray detection of G73.9+0.9, a supernova remnant interacting with a molecular cloud. https://doi.org/10.1093/mnras/stv2167

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