相关论文: Three-dimensional simulations of long duration gam…

We present the results of hydrodynamical simulations of gamma-ray burst jets propagating through their stellar progenitor material and subsequently through the surrounding circumstellar medium. We consider both jets that are injected with…

We present the results of a set of numerical simulations of long-duration gamma-ray burst jets aimed at studying the effect of a variable engine on the peak frequency of the photospheric emission. Our simulations follow the propagation of…

The prompt emission of gamma-ray bursts (GRBs) is characterized by rapid variabilities, which may be a direct reflection of the unsteady central engine. We perform a series of axisymmetric 2.5-dimensional simulations to study the…

The duration of the prompt emission of long gamma-ray bursts is generally considered to be fairly similar to the duration of the activity of the engine in the center of the progenitor star. Here, we investigate the relation between the…

Strong variability is a common characteristic of the prompt emission of gamma-ray bursts (GRB). This observed variability is widely attributed to an intermittency of the central engine, through formation of strong internal shocks in the…

It is now generally accepted that long gamma-ray bursts are associated with the final evolutionary stages of massive stars. As a consequence, their jets must propagate through the stellar progenitor and break out on their surface, before…

We present a numerical simulation of a gamma-ray burst jet from a long-lasting engine in the core of a 16 solar mass Wolf-Rayet star. The engine is kept active for 6000 s with a luminosity that decays in time as a power-law with index -5/3.…

We investigate by two-dimensional axisymmetric relativistic hydrodynamical simulations (1) jet propagations through an envelope of a rapidly rotating and collapsing massive star, which is supposed to be a progenitor of long duration gamma…

The duration distribution of long Gamma Ray Bursts reveals a plateau at durations shorter than ~20 s (in the observer frame) and a power-law decline at longer durations (Bromberg et al., 2012). Such a plateau arises naturally in the…

Jets in long-duration $\gamma$-ray bursts (GRBs) have to drill through the collapsing star in order to break out of it and produce the $\gamma$-ray signal while the central engine is still active. If the breakout time is shorter for more…

After the detection of GRB 170817A, the first unambiguous off-axis gamma-ray burst (GRB), several studies tried to understand the structure of GRB jets. The initial jet structure (directly produced by the central engine) can be partially…

Context. The complexity and variety exhibited by the light curves of long gamma-ray bursts (GRBs) enclose a wealth of information that still awaits being fully deciphered. Despite the tremendous advance in the knowledge of the energetics,…

We perform a statistical analysis of the temporal structure of long Gamma-Ray-Bursts (GRBs). First we consider a sample of bursts in which a long quiescent time is present. Comparing the pre-quiescence with the post-quiescence emission we…

We consider the transverse structure and stability properties of relativistic jets formed in the course of the collapse of a massive progenitor. Our numerical simulations show the presence of a strong shear in the bulk velocity of such…

We propose that gamma-ray burst pulses are produced when highly-relativistic jets sweep across an observer's line-of-sight. We hypothesize that axisymmetric jet profiles, coupled with special relativistic effects, produce the time-reversed…

We review the observational differences between gamma-ray bursts occurring on a single shell (such as in the external shock model) and multiple shells (such as in the internal shock model). We do not argue against external shocks or for…

The association of at least some long gamma-ray bursts with type Ic supernova explosions has been established beyond reasonable doubt. Theoretically, the challenge is to explain the presence of a light hyper-relativistic flow propagating…

We study the long-term evolution of relativistic jets in collapsars and examine the effects of viewing angle on the subsequent gamma ray bursts. We carry out a series of high-resolution simulations of a jet propagating through a stellar…

There are several lines of evidence indicating that the ultra-relativistic outflows powering gamma-ray bursts (GRBs) are collimated into narrow jets. However, these are indirect, and the jet structure is rather poorly constrained. What is…

Leading models for the "central engine" of long, soft gamma-ray bursts (GRBs) are briefly reviewed with emphasis on the collapsar model. Growing evidence supports the hypothesis that GRBs are a supernova-like phenomenon occurring in star…