Pursuing the origin of the gamma rays in RX J1713.7$-$3946 quantifying the hadronic and leptonic components

Abstract

We analyzed the TeV gamma-ray image of a supernova remnant RX J1713.7$-$3946 (RX J1713) through a comparison with the interstellar medium (ISM) and the non-thermal X-rays. The gamma-ray datasets at two energy bands of $>$2 TeV and $>$250-300 GeV were obtained with H.E.S.S. (H.E.S.S. Collaboration 2018; Aharonian et al. 2007) and utilized in the analysis. We employed a new methodology which assumes that the gamma-ray counts are expressed by a linear combination of two terms; one is proportional to the ISM column density and the other proportional to the X-ray count. We then assume these represent the hadronic and leptonic components, respectively. By fitting the expression to the data pixels, we find that the gamma-ray counts are well represented by a flat plane in a 3D space of the gamma-ray counts, the ISM column density and the X-ray counts. The results using the latest H.E.S.S. data at 4.8 arcmin resolution show that the hadronic and leptonic components occupy $(67\pm 8)$% and $(33\pm 8)$% of the total gamma rays, respectively, where the two components have been quantified for the first time. The hadronic component is greater than the leptonic component, which reflects the massive ISM of $\sim$10${}^4$ $M_{\odot }$ associated with the SNR, lending support for the acceleration of the cosmic-ray protons. There is a marginal hint that the gamma rays are suppressed at high gamma-ray counts which may be ascribed to the second order effects including the shock-cloud interaction and the penetration-depth effect.

20 pages, 9 figures, 3 tables, accepted for publication in The Astrophysical Journal (ApJ)

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• Observations of the young supernova remnant RX J1713.7-3946 with the Fermi Large Area Telescope
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• Gamma rays from molecular clouds
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• 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
• Shock-Cloud Interaction in the Southwestern Rim of RX J1713.7$-$3946 Evidenced by Chandra X-ray Observations
• NuSTAR observations of the supernova remnant RX J1713.7$-$3946
• Optical reconstruction of dust in the region of SNR RX J1713.7-3946 from astrometric data

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• Detection of a new molecular cloud in the LHAASO J2108+5157 region supporting a hadronic PeVatron scenario
• Molecular and Atomic Clouds Associated with the Gamma-Ray Supernova Remnant Puppis A
• X-ray Line Diagnostics of Ion Temperature at Cosmic-Ray Accelerating Collisionless Shocks
• Prospects for combined analyses of hadronic emission from $\gamma$-ray sources in the Milky Way with CTA and KM3NeT
• The Gamma-Ray Emission from the Supernova Remnant RX J1713.7-3946 Interacting with Two-phase Medium
• Expansion and ongoing cosmic ray acceleration in HESS J1731-347
• Evidence for protons accelerated and escaped from the Puppis A region using \textit{Fermi}-LAT observations
• Modelling the Gamma-Ray Morphology of HESS J1804-216 from Two Supernova Remnants in a Hadronic Scenario
• Survival of Molecular Complexity under Recent Supernova Feedback: Detection of Hot Cores in RX J1713.7-3946
• Observations of ionized carbon towards the $\gamma$-ray-bright supernova remnant RX J1713.7-3946