LMC N132D

• Verfasst von: Abdalla, Hassan [VerfasserIn]
• Verfasst von: Jankowsky, Felix [VerfasserIn]
• Verfasst von: Lypova, Iryna [VerfasserIn]
• Verfasst von: Marx, Ramin [VerfasserIn]
• Verfasst von: Quirrenbach, Andreas [VerfasserIn]
• Verfasst von: Wagner, Stefan [VerfasserIn]
• Titel: LMC N132D
• Titelzusatz: a mature supernova remnant with a power-law gamma-ray spectrum extending beyond 8 TeV
• Körperschaft: H.E.S.S. Collaboration [VerfasserIn]
• Verf.angabe: H.E.S.S. Collaboration*
• E-Jahr: 2021
• Jahr: 28 October 2021
• Umfang: 13 S.
• Fussnoten: *H.E.S.S. Collaboration: H. Abdalla, F. Jankowsky, I. Lypova, R. Marx, A. Quirrenbach, S.J. Wagner [und 222 weitere Personen] ; Gesehen am 16.12.2021
• Titel Quelle: Enthalten in: Astronomy and astrophysics
• Ort Quelle: Les Ulis : EDP Sciences, 1969
• Jahr Quelle: 2021
• Band/Heft Quelle: 655(2021), Artikel-ID A7, Seite 1-13
• ISSN Quelle: 1432-0746
• DOI: doi:10.1051/0004-6361/202141486
• Datenträger: Online-Ressource
• Sprache: eng
• K10plus-PPN: 1782351183

Abstract

Context: Supernova remnants (SNRs) are commonly thought to be the dominant sources of Galactic cosmic rays up to the knee of the cosmic-ray spectrum at a few PeV. Imaging Atmospheric Cherenkov Telescopes have revealed young SNRs as very-high-energy (VHE, >100 GeV) gamma-ray sources, but for only a few SNRs the hadronic cosmic-ray origin of their gamma-ray emission is indisputably established. In all these cases, the gamma-ray spectra exhibit a spectral cutoff at energies much below 100 TeV and thus do not reach the PeVatron regime. Aims: The aim of this work was to achieve a firm detection for the oxygen-rich SNR LMC N132D in the VHE gamma-ray domain with an extended set of data, and to clarify the spectral characteristics and the localization of the gamma-ray emission from this exceptionally powerful gamma-ray-emitting SNR. Methods: We analyzed 252 h of High Energy Stereoscopic System (H.E.S.S.) observations towards SNR N132D that were accumulated between December 2004 and March 2016 during a deep survey of the Large Magellanic Cloud, adding 104 h of observations to the previously published data set to ensure a > 5σ detection. To broaden the gamma-ray spectral coverage required for modeling the spectral energy distribution, an analysis of Fermi-LAT Pass 8 data was also included. Results: We unambiguously detect N132D at VHE with a significance of 5.7σ. We report the results of a detailed analysis of its spectrum and localization based on the extended H.E.S.S. data set. The joint analysis of the extended H.E.S.S and Fermi-LAT data results in a spectral energy distribution in the energy range from 1.7 GeV to 14.8 TeV, which suggests a high luminosity of N132D at GeV and TeV energies. We set a lower limit on a gamma-ray cutoff energy of 8 TeV with a confidence level of 95%. The new gamma-ray spectrum as well as multiwavelength observations of N132D when compared to physical models suggests a hadronic origin of the VHE gamma-ray emission. Conclusions: SNR N132D is a VHE gamma-ray source that shows a spectrum extending to the VHE domain without a spectral cutoff at a few TeV, unlike the younger oxygen-rich SNR Cassiopeia A. The gamma-ray emission is best explained by a dominant hadronic component formed by diffusive shock acceleration. The gamma-ray properties of N132D may be affected by an interaction with a nearby molecular cloud that partially lies inside the 95% confidence region of the source position.