Related papers: Low angular momentum accretion in the collapsar: h…
Long gamma-ray bursts (lGRB) are produced by relativistic jets arising from the collapse of massive stars. Such progenitor environments present complex physical conditions that are challenging to model by numerical simulations. The…
We present the analysis of the extraordinarily bright Gamma-Ray Burst (GRB) 130427A under the hypothesis that the GRB central engine is an accretion-powered magnetar. In this framework, initially proposed to explain GRBs with precursor…
Discovered over forty years ago, Gamma-Ray Bursts (GRBs) remain a forefront topic in modern astrophysics. Perhaps the most fundamental question associated with GRBs is the nature of the astrophysical agent (or agents) that ultimately powers…
Recent VLT SINFONI observations of the close environments (~30pc) of nearby AGNs have shown that thick gas tori and starbursts with ages between 10 and 150Myr are frequently found. By applying these observations to a previously established…
We present a suite of the first 3D GRMHD collapsar simulations, which extend from the self-consistent jet launching by an accreting Kerr black hole (BH) to the breakout from the star. We identify three types of outflows, depending on the…
Strongly-magnetized, rapidly-rotating neutron stars are contenders for the central engines of both long-duration gamma-ray bursts (LGRBs) and hydrogen-poor super-luminous supernovae (SLSNe-I). Models for typical (~minute long) LGRBs invoke…
Gamma-ray bursts (GRBs) show a bimodal distribution of durations, separated at a duration of ~2 s. Observations have confirmed the association of long GRBs with the collapse of massive stars. The origin of short GRBs is still being…
A hyperaccretion flow around a stellar mass black hole is thought to be the most plausible engine that powers gamma-ray bursts (GRBs). The flow efficiently cools via neutrino emission at >~ 0.003-0.01 M_sun s^{-1} (corresponding to a…
This rapporteur review summarizes results presented in Parallel Session GBT2 (Gamma Ray Burst Theory 2) on the Collapsar and Supranova Models held 25 July 2003 at the 10th Marcel Grossmann Meeting on General Relativity, Rio de Janeiro,…
The collapsar model, the now leading model for the engine behind gamma-ray bursts and hypernovae, requires that a star collapses to form a black hole surrounded by an accretion disk of high-angular momentum material. The current best…
I review aspects of the theory of long-duration gamma-ray burst (GRB) central engines. I focus on the requirements of any model; these include the angular momentum of the progenitor, the power, Lorentz factor, asymmetry, and duration of the…
We consider the spin angular momentum evolution of the accreting components of Algol-type binary stars. In wider Algols the accretion is through a disc so that the accreted material can transfer enough angular momentum to the gainer that…
In the last few years, evidences for a long-lived and sustained engine in Gamma Ray Bursts (GRBs) have increased the attention to the so called millisecond-magnetar model, as a competitive alternative to the standard collapsar scenario. I…
It has been suggested that magnetic fields play a dynamically-important role in core-collapse explosions of massive stars. In particular, they may be important in the collapsar scenario for gamma-ray bursts (GRB), where the central engine…
The slow rotation of some young stars and the extreme rotation periods of some Ap stars have so far defied explanation. The absence of sufficiently efficient braking mechanisms for newly formed stars points to the star formation process…
We assess the variance of the post-collapse evolution remnants of compact, massive, low-metallicity stars, under small changes in the degrees of rotation and magnetic field of selected pre-supernova cores. These stellar models are commonly…
The current generation of millimeter interferometers have revealed a population of compact (r <~ 0.1 pc), massive (M ~ 100 Msun) gas cores that are the likely progenitors of massive stars. I review models for the evolution of these objects…
Recent three dimensional, high-resolution simulations of neutron star coalescences are analysed to assess whether short gamma-ray bursts (GRBs) could originate from such encounters. The two most popular modes of energy extraction -- namely…
Fast radio bursts (FRBs) last for $\sim $ few milli-seconds and, hence, are likely to arise from the gravitational collapse of supra-massive, spinning neutron stars after they lose the centrifugal support (Falcke \& Rezzolla 2014). In this…
One of the most elusive features of Gamma Ray Bursts (GRBs) is the sporadic emission prior to the main prompt event observed in at least $\sim 15\%$ of cases. These precursors have spectral and temporal properties similar to the main prompt…