Related papers: Gamma rays from molecular clouds illuminated by co…
The supernova remnant (SNR) G150.3+4.5 was first identified in radio, exhibiting a hard GeV spectrum and a $\sim 1.5^\circ$ radius. Radio observations revealed a bright arc with an index of $\sim -0.40$, which stands in contrast to the…
Observations of the middle-aged supernova remnants IC 443, W28 and W51C indicate that the brightnesses at GeV and TeV energies are correlated with each other and with regions of molecular clump interaction, but not with the radio…
The contribution of Source Cosmic Rays (SCRs), accelerated and still confined in Supernova Remnants (SNRs), to the diffuse high energy \gr emission above 1 GeV from the Galactic disk is studied. The \grs produced by the SCRs have a much…
GeV and TeV emission from the forward shocks of supernova remnants (SNRs) indicates that they are capable particle accelerators, making them promising sources of Galactic cosmic rays (CRs). However, it remains uncertain whether this…
We analyze the processes governing cosmic-ray (CR) penetration into molecular clouds and the resulting generation of gamma-ray emission. The density of CRs inside a cloud is depleted at lower energies due to the self-excited MHD turbulence.…
The discovery of bright gamma-ray emission coincident with supernova remnant (SNR) W51C is reported using the Large Area Telescope (LAT) on board the Fermi Gamma-ray Space Telescope. W51C is a middle-aged remnant (~10^4 yr) with intense…
Supernova Remnants (SNRs) are believed to be the main source of Galactic cosmic rays (CR). The strong SNR shocks provide ideal acceleration sites for particles of at least 10^14 eV/nucleon. Radio continuum studies of SNRs carried out with…
It is believed that the observed diffuse gamma ray emission from the galactic plane is the result of interactions between cosmic rays and the interstellar gas. Such emission can be amplified if cosmic rays penetrate into dense molecular…
Star-forming regions on different scales, such as giant molecular clouds in our Galaxy and star-forming galaxies, emit GeV gamma-rays. These are thought to originate from hadronic interactions of cosmic-ray (CR) nuclei with the interstellar…
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…
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…
Based on the 13.7~yr Fermi-LAT data, Yeung et al. (2023) claimed detection of two $\gamma$-ray sources (Src-NE and Src-NW) associated with the supernova remnant (SNR) G298.6$-$0.0, and interpreted it as an old GeV SNR interacting with…
If supernova remnants (SNRs) are the sites of cosmic-ray acceleration, the associated nuclear interactions should result in observable fluxes of TeV gamma-rays from the nearest SNRs. Measurements of the gamma-ray flux from six nearby,…
A new cosmological scenario for the origin of gamma ray bursts (GRBs) is proposed. In our scenario, a highly evolved central core in the dense galactic nucleus is formed containing a subsystem of compact stellar remnants (CSRs), such as…
The gamma-ray & neutrino visibility of cosmic ray (CR) accelerators will be dramatically increased by the presence of molecular material abutting such sites due to the increased probability of pion production -- and, in the case of neutral…
We propose that the cosmological gamma ray bursts arise from the collapse of neutron stars to black holes triggered by collisions or mergers with main sequence stars. This scenario represents a cosmological history qualitatively different…
Energetic gamma rays (GeV to TeV photon energy) have been detected toward several supernova remnants (SNR) associated with molecular clouds. If the gamma rays are produced mainly by hadronic processes rather than leptonic processes like…
Supernova remnants are believed to be the main sources of galactic Cosmic Rays (CR). Within this framework, particles are accelerated at supernova remnant shocks and then released in the interstellar medium. The mechanism through which CRs…
We review recent progress in elucidating the relationship between high-energy radiation and the interstellar medium (ISM) in young supernova remnants (SNRs) with ages of $\sim$2000 yr, focusing in particular on RX J1713.7$-$3946 and RCW 86.…
Recent observations of galactic cosmic rays (CR) in the 1-500 GeV energy range have revealed striking deviations from what deemed "standard." The anomalies cut across hadronic and leptonic CRs. I discuss findings that challenge physical…