Related papers: Long Gamma-Ray Transients from Collapsars
Long-duration gamma-ray bursts (lGRBs) originate in relativistic collimated outflows -- jets -- that drill their way out of collapsing massive stars. Accurately modeling this process requires realistic stellar profiles for the jets to…
Gamma-ray bursts (GRBs) are flashes of high-energy radiation arising from energetic cosmic explosions. Bursts of long (>2 s) duration are produced by the core-collapse of massive stars, those of short (< 2 s) duration by the merger of two…
Cosmological gamma-ray bursts (GRBs) could be driven by dissipation of pure electromagnetic energy (Poynting flux) extracted from rapidly rotating compact objects with strong magnetic fields. One such possibility is a young millisecond…
We present a scenario (SupraNova) for the formation of GRBs occurring when a supramassive neutron star (SMNS) loses so much angular momentum that centrifugal support against self--gravity becomes impossible, and the star implodes to a black…
The theory underlying the evolution and death of stars heavier than 10 Msun on the main sequence is reviewed with an emphasis upon stars much heavier than 30 Msun. These are stars that, in the absence of substantial mass loss, are expected…
We investigate the triggering of star formation in clouds that form in Galactic scale flows as the ISM passes through spiral shocks. We use the Lagrangian nature of SPH simulations to trace how the star forming gas is gathered into…
Growing observational evidence supports the proposition that gamma-ray bursts (GRBs) are powered by relativistic jets from massive helium stars whose cores have collapsed to black holes and an accretion disk (collapsars). We model the…
The energy source has remained to be the great mystery in understanding of the gamma-ray bursts (GRBs) if the events are placed at cosmological distances as indicated by a number of recent observations. The currently popular models include…
In this work I summarize a model of binary stellar evolution involving Case C mass transfer followed by a common envelope that strips away the hydrogen from the core of the primary star at the cost of shrinking the orbital separation and…
Precursor emission has been observed in a non-negligible fraction of gamma-ray bursts.The time gap between the precursor and the main burst extends in some case up to hundreds of seconds, such as in GRB041219A, GRB050820A and GRB060124.…
Supermassive disks are thought to be precursors of supermassive black holes that are believed to power quasars and exist at centers of galaxies. Formation scenarios of such disks are reviewed and it is argued that gas dynamical schemes are…
Observational evidence suggests a link between long duration gamma ray bursts (LGRBs) and Type Ic supernovae. Here, we propose a potential mechanism for Type Ic supernovae in LGRB progenitors powered solely by accretion energy. We present…
We propose a scenario in which massive stars form at the outer edges of an AGN accretion disc. We analyze the dynamics of a disc forming around a supermassive black hole, in which the angular momentum is transported by turbulence induced by…
The Galactic hard X-ray transient SWIFT J195509+261406 was first observed as a gamma-ray burst GRB 070610. Within 3 days after the burst, more than forty optical flares had been observed. Here we propose that this peculiar event should be…
We study the structure and evolution of the hyperaccreting disks and outflows in the gamma ray bursts central engines. The torus around a stellar mass black hole is composed of free nucleons, Helium, electron-positron pairs, and is cooled…
Sgr A*, the putative black hole in our Galactic Center (GC), is extraordinary dim in all frequencies. Apparently the black hole is unable to accrete at the Bondi accretion rate for some reason. Another mystery of Sgr A* is the recently…
Gamma-ray bursts (GRBs) are cosmologically distributed, very energetic and very transient sources detected in the gamma-ray domain. The identification of their x-ray and optical afterglows allowed so far the redshift measurement of 150…
Long-duration gamma-ray bursts are associated with the explosions of massive stars and are accordingly expected to reside in star-forming regions with molecular gas (the fuel for star formation). Previous searches for carbon monoxide (CO),…
We perform two-dimensional, axisymmetric, magnetohydrodynamic simulations of the collapse of a rotating star of 40 Msun and in the light of the collapsar model of gamma-ray burst. Considering two distributions of angular momentum, up to…
When the afterglow fades at the site of a long-duration gamma-ray burst (LGRB), Type Ic supernovae (SN Ic) are the only type of core collapse supernova observed. Recent work found that a sample of LGRB in high-redshift galaxies had…