A revisited study of the unidentified $\gamma$-ray emission towards the SNR Kes 41

TL;DR

This study analyzes 9 years of Fermi-LAT data on SNR Kes 41, revealing that its gamma-ray emission can be explained by bremsstrahlung from electrons or pion-decay from hadronic collisions, with both mechanisms plausible.

Contribution

It provides a detailed spectral analysis and modeling of gamma-ray emission mechanisms for Kes 41, revisiting previous interpretations with new data and constraints.

Findings

Gamma-ray emission can be explained by bremsstrahlung from electrons.

Pion-decay from hadronic collisions remains a viable explanation.

Spectral modeling supports multiple emission scenarios.

Abstract

Kes 41 is among the Galactic supernova remnants (SNRs) proposed to be physically linked to $\gamma$-ray emission at GeV energies. Although not conclusively, the nature of the $\gamma$-ray photons has been explained by means of hadronic collisions of particles accelerated at the SNR blast wave with target protons in an adjacent molecular clump. We performed an analysis of Fermi-Large Area Telescope (LAT) data of about 9 years to assess the origin of the $\gamma$-ray emission. To investigate this matter we also used spectral modelling constraints from the physical properties of the interstellar medium towards the $\gamma$-ray emitting region along with a revised radio continuum spectrum of Kes 41 ($\alpha = -0.54 \pm 0.10$, $S\propto\nu^{\alpha}$). We demonstrated that the $\gamma$-ray fluxes in the GeV range can be explained through bremsstrahlung emission from electrons interacting with the surrounding medium. We also consider a model in which the emission is produced by pion-decay after hadronic collisions, and confirmed that this mechanism cannot be excluded.