Fermi-LAT Detection of a Break in the Gamma-Ray Spectrum of the Supernova Remnant Cassiopeia A

Abstract

We report on observations of the supernova remnant Cassiopeia A in the energy range from 100 MeV to 100 GeV using 44 months of observations from the Large Area Telescope on board the Fermi Gamma-ray Space Telescope. We perform a detailed spectral analysis of this source and report on a low-energy break in the spectrum at $1.72_{-0.89}^{+1.35}$ GeV. By comparing the results with models for the gamma-ray emission, we find that hadronic emission is preferred for the GeV energy range.

18 pages, 5 figures, 2 tables, to be published in ApJ

References in corpus (7)

• Detection of the Characteristic Pion-Decay Signature in Supernova Remnants
• Observational constraints on energetic particle diffusion in young SNRs: amplified magnetic field and maximum energy
• Characterizing the non-thermal emission of Cas A
• Fast Variability of Nonthermal X-Ray Emission in Cassiopeia A: Probing Electron Acceleration in Reverse-Shocked Ejecta
• Observations of the shell-type SNR Cassiopeia A at TeV energies with VERITAS
• A dedicated Chandra ACIS observation of the central compact object in the Cassiopeia A supernova remnant
• Small-Scale X-ray Variability in the Cassiopeia A Supernova Remnant

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• Measurement of the Crab Nebula Spectrum Past 100 TeV with HAWC
• Modeling SNR Cassiopeia A from the Supernova Explosion to its Current Age: The role of post-explosion anisotropies of ejecta
• Space- and Ground-Based Gamma-Ray Astrophysics
• A cut-off in the TeV gamma-ray spectrum of the SNR Cassiopeia A
• Locating the most energetic electrons in Cassiopeia A
• Evidence for proton acceleration up to TeV energies based on VERITAS and Fermi-LAT observations of the Cas A SNR
• Proto-neutron stars as cosmic factories for massive axion-like-particles
• Improved Cosmic-Ray Injection Models and the Galactic Center Gamma-Ray Excess
• Nonthermal radiation of young supernova remnants: the case of Cas A
• Origin of gamma-ray emission in the shell of Cassiopeia A
• High-energy gamma-ray study of the dynamically young SNR G150.3+4.5
• Recent results in nuclear astrophysics
• Expectation on Observation of Supernova Remnants with the LHAASO Project
• Mapping the spectral index of Cas A: evidence for flattening from radio to infrared
• Is Supernova Remnant Cassiopeia A a PeVatron?
• Search for new cosmic-ray acceleration sites within the 4FGL catalog Galactic plane sources
• HESS J1427-608: an unusual hard unbroken $\gamma -$ray spectrum in a very wide energy range
• New estimation of the nuclear de-excitation line emission from the supernova remnant Cassiopeia A
• Resurrection of Non-thermal Emissions from Type Ib/c Supernova Remnants
• GeV emission in the region of the supernova remnant G51.26+0.11