Related papers: Multifrequency Behaviour of Galactic and Extragala…
Major advances have been made in the field of gamma-ray bursts in the last two years. The successful discovery of X-ray, optical and radio afterglows, which were predicted by theory, has made possible the identification of host galaxies at…
Starbursts are a significant component of the present-day universe, and offer unique laboratories for studying the processes that have regulated the formation and evolution of galaxies and the intergalactic medium. The combination of large…
In this article, a broad perspective of supernovae, their classification and mechanism is given. Later, the astrophysical significance of supernovae is discussed in brief.
Million degree plasmas are ubiquitous in the Universe, and examples include the atmospheres of white dwarfs; accretion phenomena in young stars, cataclysmic variables and active galactic nuclei; the coronae of stars; and the interstellar…
The Interferometric studies of novae in the optical and near-infrared is a nascent but fast emerging field which has begun to provide new and invaluable insights into the nova phenomenon. This is particularly so in the early stages of the…
The extragalactic gamma-ray sky is dominated by two classes of sources: Gamma-Ray Bursts (GRBs) and radio loud active galactic nuclei whose jets are pointing at us (blazars). We believe that the radiation we receive from them originates…
Cosmic explosions dissipate energy into their surroundings on a very wide range of time-scales: producing shock waves and associated particle acceleration. The historical culprits for the acceleration of the bulk of Galactic cosmic rays are…
Radio Galaxies have by now emerged as a new $\gamma$-ray emitting source class on the extragalactic sky. Given their remarkable observed characteristics, such as unusual gamma-ray spectra or ultrafast VHE variability, they represent unique…
Gamma-ray bursts (GRBs) are the most luminous electromagnetic burst in the Universe. They occur when a rapidly rotating massive star collapses or a binary neutron star merges. These events leave a newborn central compact object, either a…
We review infrared observations of classical and recurrent novae, at wavelengths >3microns, including both broad-band and spectroscopic observations. In recent years infrared spectroscopy in particular has revolutionised our understanding…
Multi-frequency observations are a powerful tool of astrophysical investigation. Not only is data in each wavelength band providing different clues to the objects nature, but taken simultaneously, these data can reveal the mechanisms at…
Ultra-high energy cosmic rays interacting with the radiation fields in the universe cause electromagnetic cascades resulting in a flux of extragalactic gamma rays, detectable to some 100 GeV. Recent precise measurements of the extragalactic…
Fluctuations during a prolonged maximum have been observed in several nova eruptions, although it is not clear, and can not be deduced directly from observations, if the phenomenon is an actual physical reaction to some mechanism…
Cataclysmic variables are binary stars in which a relatively normal star is transferring mass to its compact companion. This interaction gives rise to a rich range of behaviour, of which the most noticeable are the outbursts that give the…
Cosmic rays are a sample of solar, galactic and extragalactic matter. Their origin and properties are one of the most intriguing question in modern astrophysics. The most energetic events and active objects in the Universe: supernovae…
There is a wide consensus in the astrophysics community that the mechanism underlying the observed Classical Nova eruptions is a surface thermonuclear runaway. We start this short review with the main observational facts that lead to the…
Novae are now firmly established as a high-energy (>100 MeV) gamma-ray source class by the Fermi Large Area Telescope (LAT). In symbiotic binary systems such as V407 Cyg 2010, there is a firm theoretical framework for the production of…
Classical novae emit gamma-ray radiation at 511 keV and below, with a cut-off at around (20-30) keV, related to positron annihilation and its Comptonization in the expanding envelope. This emission has been elusive up to now, because it…
Classical novae are fascinating stellar events, at the crossroads of astrophysics, nuclear physics and cosmochemistry. In this review, we outline the history of nova modeling with special emphasis on recent advances and perspectives in…
In this paper, we revisit the problem of the determination of the frequency of occurrence of galactic nova outbursts which involve an oxygen-neon (ONe) white dwarf. The improvement with respect to previous work on the subject derives from…