Using Interstellar Clouds to Search for Galactic PeVatrons: Gamma-ray Signatures from Supernova Remnants

Abstract

Interstellar clouds can act as target material for hadronic cosmic rays; gamma rays subsequently produced through inelastic proton-proton collisions and spatially associated with such clouds can provide a key indicator of efficient particle acceleration. However, even in the case that particle acceleration proceeds up to PeV energies, the system of accelerator and nearby target material must fulfil a specific set of conditions in order to produce a detectable gamma-ray flux. In this study, we rigorously characterise the necessary properties of both cloud and accelerator. By using available Supernova Remnant (SNR) and interstellar cloud catalogues, we produce a ranked shortlist of the most promising target systems, those for which a detectable gamma-ray flux is predicted, in the case that particles are accelerated to PeV energies in a nearby SNR. We discuss detection prospects for future facilities including CTA, LHAASO and SWGO; and compare our predictions with known gamma-ray sources. The four interstellar clouds with the brightest predicted fluxes >100 TeV identified by this model are located at (l,b) = (333.46,-0.31), (16.97,0.53), (110.43,1.89) and (336.73,-0.98). These clouds are consistently bright under a range of model scenarios, including variation in the diffusion coefficient and particle spectrum. On average, a detectable gamma-ray flux is more likely for more massive clouds; systems with lower separation distance between the SNR and cloud; and for slightly older SNRs.

Accepted for publication in MNRAS. Revised version. 27 pages, 16 figures, 7 tables

References in corpus (23)

• The ATNF Pulsar Catalogue
• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• Observations of the Crab Nebula with H.E.S.S
• Detection of the Characteristic Pion-Decay Signature in Supernova Remnants
• Extended gamma-ray sources around pulsars constrain the origin of the positron flux at Earth
• Physical properties of molecular clouds for the entire Milky Way disk
• 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
• Searching for galactic cosmic ray pevatrons with multi-TeV gamma rays and neutrinos
• Galactic Supernova Remnant Candidates Discovered by THOR
• Faraday tomography of the local interstellar medium with LOFAR: Galactic foregrounds towards IC342
• Evidence of 200 TeV photons from HAWC J1825-134
• Discovery of the hard spectrum VHE gamma-ray source HESS J1641-463
• On the Distance and Molecular Environment of Westerlund 2 and HESS J1023-575
• Candidate radio supernova remnants observed by the GLEAM survey over $345^{\circ }<l<60^{\circ }$ and $180^{\circ }<l<240^{\circ }$
• Diffuse γ-ray emission from self-confined cosmic rays around Galactic sources
• TeV emission of Galactic plane sources with HAWC and H.E.S.S
• New candidate radio supernova remnants detected in the GLEAM survey over $345^{\circ }<l<60^{\circ }$, $180^{\circ }<l<240^{\circ }$
• Bell-Instability-Mediated Spectral Modulation of Hadronic Gamma Rays from a Supernova Remnant Interacting with a Molecular Cloud
• Interstellar gas towards the TeV gamma-ray sources HESS J1640-465 and HESS J1641-463
• Updated radio $\Sigma -D$ relation for Galactic supernova remnants -- II
• A study of the interstellar medium towards the unidentified dark TeV $\gamma$-ray sources HESS J1614-518 and HESS J1616-508
• Multi-wavelength observations of 2HWC J1928+177: dark accelerator or new TeV gamma-ray binary?

Cited by in corpus (11)

• The Hunt for Pevatrons: The Case of Supernova Remnants
• Gamma rays as probes of cosmic-ray propagation and interactions in galaxies
• Where are Milky Way's Hadronic PeVatrons?
• Sensitivity of the Cherenkov Telescope Array to spectral signatures of hadronic PeVatrons with application to Galactic Supernova Remnants
• Probing the galactic cosmic-ray density with current and future $\gamma$-ray instruments
• Detection prospects of very and ultra high-energy gamma rays from extended sources with ASTRI, CTA, and LHAASO
• The extragalactic $\gamma$-ray background: imprints from the physical properties and evolution of star-forming galaxy populations
• Probing the origin of 4FGL J0822.8-4207: cosmic ray illumination from the SNR Puppis A and the Herbig-Haro object HH219
• Detection of molecular clouds in the PeVatron candidate source LHAASO J0341$+$5258 by the Nobeyama 45-m radio telescope
• 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