Modelling the Gamma-Ray Morphology of HESS J1804-216 from Two Supernova Remnants in a Hadronic Scenario

Abstract

HESS J1804-216 is one of the brightest yet most mysterious TeV gamma-ray sources discovered to date. Previous arc-minute scale studies of the interstellar medium (ISM) surrounding this TeV gamma-ray source revealed HESS J1804-216 is likely powered by a mature supernova remnant (SNR) or pulsar, hence its origin remains uncertain. In this paper, we focus on the diffusive escape of cosmic-ray protons from potential SNR accelerators. These cosmic rays interact with the ISM to produce TeV gamma-rays. We utilise the isotropic diffusion equation solution for particles escaping from a shell, to model the energy-dependent escape and propagation of protons into the ISM. This work is the first attempt at modelling the spatial morphology of gamma-rays towards HESS J1804-216, using arc-minute ISM observations from both Mopra and the Southern Galactic Plane Survey. The spectral and spatial distributions of gamma-rays for the two nearby potential SNR counterparts, SNR G8.7-0.1 and the progenitor SNR of PSR J1803-2137, are presented here. We vary the diffusion parameters and particle spectrum and use a grid search approach to find the best combination of model parameters. We conclude that moderately slow diffusion is required for both candidates. The most promising candidate to be powering the TeV gamma-rays from HESS J1804-216 in a hadronic scenario is the progenitor SNR of PSR J1803-213.

13 pages, 13 figures, 4 tables

References in corpus (10)

• Detection of the Characteristic Pion-Decay Signature in Supernova Remnants
• Parametrization of gamma-ray production cross-sections for pp interactions in a broad proton energy range from the kinematic threshold to PeV energies
• Gamma rays from molecular clouds
• AGILE detection of GeV gamma-ray emission from the SNR W28
• Discovery of New Interacting Supernova Remnants in the Inner Galaxy
• The Mopra Southern Galactic Plane CO Survey - Data Release 3
• Pursuing the origin of the gamma rays in RX J1713.7$-$3946 quantifying the hadronic and leptonic components
• ALMA CO Observations of the Gamma-Ray Supernova Remnant RX J1713.7-3946: Discovery of Shocked Molecular Cloudlets and Filaments at 0.01 pc scales
• Using Interstellar Clouds to Search for Galactic PeVatrons: Gamma-ray Signatures from Supernova Remnants
• Arc-minute-scale studies of the interstellar gas towards HESSJ1804$-$216: Still an unidentified TeV $\gamma$-ray source