Related papers: Novae in gamma-rays
A halo model with heavy relic neutrinos N belonging to a fourth generation and their annihilations in galactic halo may explain the recent evidence of diffused gamma (GeV) radiation around galactic plane. We considered a neutrino mass in…
At high energies, the hadronic origin of gamma rays from supernova remnants is still debated. Assuming the observed gamma-rays from the Wolf-Rayet supernova remnant Cas A are due to accelerated protons and ions, we predict the nuclear…
Classical novae are among the most frequent transient events in the Milky Way, and key agents of ongoing nucleosynthesis. Despite their large numbers, they have never been observed in soft $\gamma$-ray emission. Measurements of their…
The recent discovery of a new population of ultra-high-energy gamma-ray sources with spectra extending beyond 100 TeV revealed the presence of Galactic PeVatrons - cosmic-ray factories accelerating particles to PeV energies. These sources,…
Classical novae are thermonuclear explosions that occur on the surfaces of white dwarf stars in interacting binary systems (Bode & Evans 2008). It has long been thought that the luminosity of classical novae is powered by continued nuclear…
Recent theoretical models suggest that young supernovae might be able to accelerate particles, which in turn might generate very high energy gamma-ray emission. We search for gamma-ray emission towards supernovae in nearby galaxies which…
During a core-collapse supernova, absorption of anti-nu_e emitted from the proto-neutron star by protons in the hydrogen envelope produces neutrons and positrons. Neutron capture on protons and positron annihilation then produce gamma rays…
The bulk of the cosmic rays up to about 100 TeV are thought to be accelerated by the 1st order Fermi mechanism at supernova shocks, producing a power-law spectrum. Both electrons and protons should be accelerated, but their ratio on…
Available data for novae show that the X-ray and visible spectral regions correlate with each other as they evolve. Large differences in ionization exist simultaneously in the two wavelength regimes, and a straightforward model is proposed…
A gamma-ray burst fireball is likely to contain an admixture of neutrons, in addition to protons, in essentially all progenitor scenarios. Inelastic collisions between differentially streaming protons and neutrons in the fireball produce…
Gamma-ray lines from radioactive isotopes, ejected into interstellar space by cosmic nucleosynthesis events, are observed with new space telescopes. The Compton Observatory had provided a sky survey for the isotopes 56Co, 22Na, 44Ti, and…
Besides the fact that the gamma-ray emission due to radioactive decays is responsible for powering the light curves of Type Ia supernovae (SNe Ia), gamma rays themselves are of particular interest as a diagnostic tool because they provide a…
Recent observations, particularly from the HESS Collaboration, have revealed rich Galactic populations of TeV gamma-ray sources, including a collection unseen in other wavelengths. Many of these gamma-ray spectra are well measured up to ~10…
The light curves of Type Ia Supernovae (SN Ia) are powered by gamma-rays emitted by the decay of radioactive elements such as $^{56}$Ni and its decay products. These gamma-rays are downscattered,absorbed, and eventually reprocessed into the…
The observations suggest that $\gamma$-ray bursts (GRBs) are produced by jets of relativistic cannonballs (CBs), emitted in supernova (SN) explosions. The CBs, reheated by their collision with the SN shell, emit radiation and Doppler-boost…
Motivated by the recently discovered class of faint (10^34-10^35 ergs/s) X-ray transients in the Galactic Center region, we investigate the 2-10 keV properties of classical and recurrent novae. Existing data are consistent with the idea…
Pulsed emission from gamma-ray pulsars originates inside the magnetosphere, from radiation by charged particles accelerated near the magnetic poles or in the outer gaps. In polar cap models, the high energy spectrum is cut off by magnetic…
We present the AGILE gamma-ray observations in the energy range 50 MeV - 10 GeV of the supernova remnant (SNR) W44, one of the most interesting systems for studying cosmic-ray production. W44 is an intermediate-age SNR (20, 000 years) and…
The mechanism of classical novae explosions is explained, together with some of their observational properties. The scarce but not null impact of novae in the chemical evolution of the Milky Way is analyzed, as well as their relevance for…
Recently, gamma-ray emission at TeV energies has been detected from the starburst galaxies NGC253 (Acero et al., 2009) and M82 (Acciari et al., 2009. It has been claimed that pion production due to cosmic rays accelerated in supernova…