Related papers: A model for giant flares in soft gamma repeaters
We propose a model for short duration gamma-ray bursts (sGRBs) based on the formation of a quark star after the merger of two neutron stars. We assume that the sGRB central engine is a proto-magnetar, which has been previously invoked to…
The apparently huge energy budget of the gamma ray burst GRB 990123 led to the final collapse of the isotropic fireball model, forcing even the most skeptical to consider a beamed Jet emission correlated to a supernova (SN) explosion.…
We model the 1990 giant X-ray flare of the quiescent galaxy NGC 5905 as the tidal disruption of a star by a supermassive black hole. From the observed rapid decline of the luminosity, over a timescale of a few years, we argue that the flare…
When a star undergoes core collapse, a vast amount of energy is released in a ~10 s long burst of neutrinos of all species. Inverse beta decay in the star's hydrogen envelope causes an electromagnetic cascade which ultimately results in a…
We analyzed the observations of SGR 1806-20 performed with the \textit{Rossi X-ray Timing Explorer} (RXTE) during its 2004 giant flare. We studied the phase evolution of the sub-pulses identified in the X-ray waveform and found that the…
Infrared observations of the environment of the two Soft Gamma-ray Repeaters (SGRs) with the best known locations on the sky show that they are associated to clusters of massive stars. Observations with ISO revealed that SGR 1806-20 is in a…
Observations in the near-infrared domain showed the presence of the flat core of bright late-type stars inside $\sim 0.5\,{\rm pc}$ from the Galactic center supermassive black hole (Sgr A*), while young massive OB/Wolf-Rayet stars form a…
Flares in the X-ray afterglow of gamma-ray bursts (GRBs) share more characteristics with the prompt emission than the afterglow, such as pulse profile and contained fluence. As a result, they are believed to originate from late-time…
In December 2004, the soft gamma-ray repeater SGR 1806-20 emitted the most powerful giant flare ever observed. This probably involved a large-scale rearrangement of the magnetosphere leading to observable variations in the properties of its…
Soft gamma-ray repeaters (SGR) are a class of high energy transients whose brief emissions are thought to arise from young and highly magnetized neutron stars. The exact cause for these outbursts and the nature of the energy loss remain…
Quark-novae leave behind quark stars with a surrounding metal-rich fall-back (ring-like) material. These compact remnants have high magnetic fields and are misconstrued as magnetars; however, several observational features allow us to…
It is known that Neutron Stars may be converted into more compact Strange Stars (SS) on capture/formation of a ``seed'' of strange matter. It is also known that the binding energy of the nascent hot SS is likely to be radiated as $\nu…
The most strongly magnetized neutron stars, the magnetars, have spectacular outbursts of gamma-ray flares powered by decay of the magnetic field. The rapidly changing field is strong enough that it should be able to stress and rupture the…
We explore the impact of a magnetar giant flare (GF) on the neutron star (NS) crust, and the associated baryon mass ejection. We consider that sudden magnetic energy dissipation creates a thin high-pressure shell above a portion of the NS…
The SN explosion in the closed binary can give the magnetospheric flare possessing the properties of GRB. The SN shock, flowing around the magnetosphere of a magnetized neutron star or a white dwarf, produces a narrow magnetic tail 10^9 cm…
Long gamma-ray bursts (GRBs) are believed to be related to the explosion of type Ic supernovae, which have been stripped of their hydrogen and helium envelopes. There appear to be two types of these explosions: those which are approximately…
The accretion of ~ 0.1 -- 1 M_o of material by a neutron star through Roche lobe overflow of its companion or through white-dwarf/neutron-star coalescence in a low mass binary system could be enough to exceed the critical mass of a neutron…
We analyze here late evolutionary stages of massive (with initial mass higher than 8 masses of the Sun) close binary stars. Our purposes are to study possible mechanisms of gamma ray bursts (GRBs) origin. We suppose in this paper that GRB…
Massive stars generally end their lives as neutron stars (NSs) or black holes (BHs), with NS formation typically occurring at the low mass end and collapse to a BH more likely at the high mass end. In an intermediate regime, with a mass…
Mergers of spinning black holes can give recoil velocities from gravitational radiation up to several thousand km/s. A recoiling supermassive black hole in an AGN retains the inner part of its accretion disk. Marginally bound material…