Gamma rays and neutrinos from RX J1713.7-3946 in a lepto-hadronic scenario

TL;DR

This paper models gamma-ray and neutrino emissions from RX J1713.7-3946, highlighting the roles of reaccelerated cosmic rays and a lepto-hadronic scenario, and suggests neutrino detection prospects.

Contribution

It introduces a comprehensive lepto-hadronic model including reacceleration of pre-existing cosmic rays to explain gamma-ray spectra.

Findings

Gamma-ray emission can be explained by reaccelerated CR electrons and protons.

Leptonic emission from reaccelerated electrons is significant in the TeV range.

Neutrino detection is possible with next-generation detectors even in a lepto-hadronic scenario.

Abstract

The gamma-ray emission of RX J1713.7-3946, despite being extensively studied in the GeV and TeV domain, remains poorly understood. This is mostly because in this range, two competing mechanisms can efficiently produce gamma rays: the inverse Compton scattering of accelerated electrons, and interactions of accelerated protons with nuclei of the ISM. In addition to the acceleration of particles from the thermal pool, the reacceleration of pre-existing CRs is often overlooked, and shall in fact also been taken into account. Especially, because of the distance to the SNR ($\sim 1$ kpc), and the low density in which the shock is currently expanding ($\sim 10^{-2}$ cm$^{-3}$), the re-acceleration of CR electrons pre-existing in the ISM, can account for a significant fraction of the observed gamma-ray emission, and contribute to the shaping of the spectrum in the GeV-TeV range. Remarkably, this emission of leptonic origin is found to be close to the level of the gamma-ray signal in the TeV range, provided that the spectrum of pre-exisiting cosmic ray electrons is similar to the one observed in the local interstellar medium. The overall gamma-ray spectrum of RX J1713.7-3946 is naturally produced as the sum of a leptonic emission from reaccelerated CR electrons, and a subdominant hadronic emission from accelerated protons. We also argue that neutrino observations with next-generation detectors might lead to a detection even in the case of a lepto-hadronic origin of the gamma-ray emission.