Origin of the gamma-ray emission from supernova remnant HB9

TL;DR

This study analyzes gamma-ray emission from supernova remnant HB9, exploring its spectral properties and potential interactions with surrounding molecular gas to understand the origin of its high-energy radiation.

Contribution

It provides detailed gamma-ray spectral modeling of HB9, investigating the hadronic emission signature and the interaction with molecular clouds, which was not previously characterized.

Findings

Gamma-ray emission is consistent with a log-parabola spectrum.

Evidence suggests possible interaction between the SNR and molecular gas.

Spectral modeling indicates potential hadronic origin of gamma rays.

Abstract

HB9 (G160.9+2.6) is a mixed-morphology Galactic supernova remnant (SNR) at a distance of $\sim$0.6 kpc. Previous analyses revealed recombining plasma emission in X-rays and an expanding shell structure in HI and CO emission, which were correlating with the spatial extent of HB9. In GeV energies, HB9 was found to show extended gamma-ray emission with a morphology that is consistent with the radio continuum emission showing a log-parabola-type spectrum. The overlap reported between the gas data and the excess gamma-ray emission at the southern region of the SNR's shell could indicate a possible interaction between them. We searched for hadronic gamma-ray emission signature in the spectrum to uncover possible interaction between the molecular environment and the SNR. Here we report the results of the gamma-ray spectral modelling studies of HB9.