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Young supernova remnants (SNRs) are believed to be the origin of energetic cosmic rays (CRs) below the "knee" of their spectrum at $\sim3$ petaelectronvolt (PeV, $10^{15}$ eV). Nevertheless, the precise location, duration, and operation of…

The all-particle spectrum of cosmic rays measured at Earth has a knee-like feature around 4 PeV. A priori, it is not clear if this is a local feature specific to the Solar neighbourhood in the Milky Way, or if it is a generic property of…

High Energy Astrophysical Phenomena · Physics 2025-07-17 C. Prevotat , M. Kachelriess , S. Koldobskiy , A. Neronov , D. Semikoz

It is widely believed that supernova remnants are the best candidate sources for the observed cosmic ray flux up to the knee, i.e. up to ~PeV energies. Indeed, the gamma-ray spectra of some supernova remnants can be well explained by…

High Energy Astrophysical Phenomena · Physics 2015-09-02 Nils Nierstenhoefer , Philipp Graeser , Florian Schuppan , Julia Becker Tjus

Supernova remnants (SNRs) are thought to be the most promising sources of Galactic cosmic rays. One of the principal questions is whether they are accelerating particles up to the maximum energy of Galactic cosmic rays ($\sim$ PeV). In this…

High Energy Astrophysical Phenomena · Physics 2022-01-19 Hiromasa Suzuki , Aya Bamba , Ryo Yamazaki , Yutaka Ohira

Supernova (SN) remnants are a well motivated candidate for the acceleration sites of cosmic rays with energies up to the knee (10^15 eV). It has been suggested that also young SNe (~<1 year after the explosion) may be able to accelerate…

High Energy Astrophysical Phenomena · Physics 2019-08-14 D. Lennarz

Galactic cosmic ray (CR) acceleration to the knee in the spectrum at a few PeV is only possible if the magnetic field ahead of a supernova remnant (SNR) shock is strongly amplified by CR escaping the SNR. A model formulated in terms of the…

High Energy Astrophysical Phenomena · Physics 2015-06-12 AR Bell , KM Schure , B Reville , G Giacinti

Supernova remnants have long been suggested as a class of potential counterparts to unidentified gamma-ray sources. The mechanisms by which such gamma-rays can arise may include emission from a pulsar associated with a remnant, or a variety…

Astrophysics · Physics 2007-05-23 Patrick Slane

In the 1960s, the remnants of supernova explosions (SNRs) were indicated as a possible source of galactic cosmic rays through the Diffusive Shock Acceleration (DSA) mechanism. Since then, the observation of gamma-ray emission from…

High Energy Astrophysical Phenomena · Physics 2024-05-28 Andrea Giuliani , Martina Cardillo

We report the detection of high-energy $\gamma$-ray emission in the vicinity of G172.8+1.5, which is debated as a Supernova remnant (SNR) or an ionized hydrogen (H$_{\rm{II}}$) region. Using 16-yr Pass 8 data from Fermi Large Area Telescope…

High Energy Astrophysical Phenomena · Physics 2025-10-03 Yuan Li , Gwenael Giacinti , Siming Liu

Supernova remnants (SNRs) are widely considered the most likely source of cosmic rays below the knee ($10^{15}$ eV). Studies of GeV and TeV gamma-ray emission in the vicinity of SNRs, in combination with multi-wavelength observations, can…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Amanda Weinstein

A nonlinear kinetic theory, combining cosmic-ray (CR) acceleration in supernova remnants (SNRs) with their gas dynamics, is used to re-examine the nonthermal properties of the remnant of SN 1987A for an extended evolutionary period of 5-50…

High Energy Astrophysical Phenomena · Physics 2015-09-16 E. G. Berezhko , L. T. Ksenofontov , H. J. Voelk

Recent results from the HESS gamma ray telescope have shown the presence of both a diffuse, extended, flux of gamma rays above ~0.4 TeV and discrete sources in and near the Galactic Centre. Here, we put forward a possible explanation in…

Astrophysics · Physics 2009-06-23 A. D. Erlykin , A. W. Wolfendale

Star-forming and starburst galaxies are considered as one of the viable candidate sources of the high-energy cosmic neutrino background detected in IceCube. We revisit contributions of supernova remnants (SNRs) and hypernova remnants (HNRs)…

High Energy Astrophysical Phenomena · Physics 2016-09-27 Di Xiao , Peter Mészáros , Kohta Murase , Zi-gao Dai

Kepler's supernova remnant (SNR) which is produced by the most recent naked-eye supernova in our Galaxy is one of the best studied SNRs, but its gamma-ray detection has eluded us so far. Observations with modern imaging atmospheric…

High Energy Astrophysical Phenomena · Physics 2021-07-27 Dmitry Prokhorov , Jacco Vink , Rachel Simoni , Nukri Komin , Stefan Funk , Denys Malyshev , Lars Mohrmann , Stefan Ohm , Gerd Pühlhofer , Heinrich J. Völk

The distribution of the very-high-energy diffuse emission in the inner 200 pc measured by HE.S.S. indicates the existence of a pronounced cosmic-ray (CR) gradient peaking on the Galactic center (GC). Previous studies have shown that these…

High Energy Astrophysical Phenomena · Physics 2021-01-04 L. Jouvin , A. Lemière , R. Terrier

Recent measurements of cosmic-ray spectra of several individual nuclear species by the CREAM, TRACER, and ATIC experiments indicate a change in the spectral index of the power laws at TeV energies. Possible explanations among others include…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Satyendra Thoudam , Jörg R. Hörandel

Observations of diffuse Galactic gamma-ray spectrum by the EGRET instrument reveal an excess above ~ 1 GeV over the expected gamma-ray spectrum calculated under the assumption that the locally observed cosmic-ray (CR) spectra represent the…

Astrophysics · Physics 2009-11-11 Thoudam Satyendra

Recently, gamma-ray telescopes AGILE and Fermi observed several middle-aged supernova remnants (SNRs) interacting with molecular clouds. It is likely that their gamma rays arise from the decay of neutral pions produced by the inelastic…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Yutaka Ohira , Kohta Murase , Ryo Yamazaki

Context: Cosmic rays are thought to be accelerated at supernova remnant (SNR) shocks, but conclusive evidence is lacking. Aims: New data from ground-based gamma-ray telescopes and the Large Area Telescope on the Fermi Gamma-ray Space…

High Energy Astrophysical Phenomena · Physics 2015-06-11 C. D. Dermer , G. Powale

Evidences of non-thermal X-ray emission and TeV gamma-rays from the supernova remnants (SNRs) has strengthened the hypothesis that primary Galactic cosmic-ray electrons are accelerated in SNRs. High energy electrons lose energy via…

Astrophysics · Physics 2009-11-10 T. Kobayashi , Y. Komori , K. Yoshida , J. Nishimura