H.E.S.S. observations of RX J1713.7-3946 with improved angular and spectral resolution; evidence for gamma-ray emission extending beyond the X-ray emitting shell

TL;DR

This paper presents enhanced H.E.S.S. gamma-ray observations of supernova remnant RX J1713.7-3946, revealing detailed morphology, evidence of particles escaping the shock, and insights into the emission mechanisms.

Contribution

The study provides the most detailed gamma-ray morphology and spectral analysis of RX J1713.7-3946 to date, with improved resolution and sensitivity, and evidence of particle escape beyond the shock region.

Findings

Unprecedented angular resolution probes physical scales of 0.6-0.8 parsecs.

First indication of particles leaving the acceleration shock region.

Insights into leptonic versus hadronic gamma-ray emission mechanisms.

Abstract

Supernova remnants exhibit shock fronts (shells) that can accelerate charged particles up to very high energies. In the past decade, measurements of a handful of shell-type supernova remnants in very-high-energy gamma rays have provided unique insights into the acceleration process. Among those objects, RX$~$J1713.7-3946 (also known as G347.3-0.5) has the largest surface brightness, allowing us in the past to perform the most comprehensive study of morphology and spatially resolved spectra of any such very-high-energy gamma-ray source. Here we present extensive new H.E.S.S. measurements of RX$~$J1713.7-3946, almost doubling the observation time compared to our previous publication. Combined with new improved analysis tools, the previous sensitivity is more than doubled. The H.E.S.S. angular resolution of $0.048^\circ$ ($0.036^\circ$ above 2 TeV) is unprecedented in gamma-ray astronomy and probes physical scales of 0.8 (0.6) parsec at the remnant's location. The new H.E.S.S. image of RX$~$J1713.7-3946 allows us to reveal clear morphological differences between X-rays and gamma rays. In particular, for the outer edge of the brightest shell region, we find the first ever indication for particles in the process of leaving the acceleration shock region. By studying the broadband energy spectrum, we furthermore extract properties of the parent particle populations, providing new input to the discussion of the leptonic or hadronic nature of the gamma-ray emission mechanism.