Related papers: On the Composition of GRBs' Collapsar Jets
We consider a model for the low-luminosity gamma-ray burst GRB 060218 that plausibly accounts for multiwavelength observations to day 20. The model components are: (1) a long-lived ($t_j \sim 3000$ s) central engine and accompanying…
The first neutron star binary merger detected in gravitational waves, GW170817 and the subsequent detection of its emission across the electromagnetic spectrum showed that these systems are viable progenitors of short $\gamma$-ray bursts…
In this paper, we carry out a semi-analytic general relativistic study of a Gamma-Ray Bursts (GRB) jet that is breaking out of a cocoon or stellar envelope. We solve hydrodynamic equations with the relativistic equation of state that takes…
Gamma-ray burst (GRB) central engines and jet production mechanisms are still open questions. Assuming that the shallow decay segments of canonical X-ray afterglow lightcurves of {\em Swift} GRBs are attributed to the magnetic dipole (MD)…
Over the past decade our physical understanding of gamma-ray bursts (GRBs) has progressed rapidly thanks to the discovery and observation of their long-lived afterglow emission. Long-duration (T < 2 s) GRBs are associated with the explosive…
For decades, gamma-ray bursts (GRBs) have been broadly divided into `long'- and `short'-duration bursts, lasting more or less than 2s, respectively. However, this dichotomy does not map perfectly to the two progenitor channels that are…
The radiation mechanism (thermal photosphere or magnetic synchrotron) and the progenitor of gamma-ray burst (GRB) are under hot debate. Recently discovered, the prompt long-duration ($\sim$ 10 s, normally from the collapse of massive stars)…
The collapse of massive rotating stellar cores and the associated accretion onto the newborn compact object is thought to power long gamma ray bursts (GRBs). The physical scale and dynamics of the accretion disk are initially set by the…
Many models of cosmological gamma-ray bursts involve the sudden release of $\sim 10^{51}$ erg which produce shells which expand at relativistic speeds (Lorentz $\Gamma$ factors of $10^{2-3}$). We investigate the kinematic limits on the…
Due to relativistic bulk motion, the structure and orientation of gamma-ray burst jets have a fundamental role in determining how they appear. The recent discovery of the GW170817 binary neutron star merger and the associated GRB boosted…
Gamma-ray bursts (GRBs) are powered by relativistic jets that exhibit intermittency over a broad range of timescales - from $ \sim $ ms to seconds. Previous numerical studies have shown that hydrodynamic (i.e., unmagnetized) jets that are…
We study the distribution of the durations of gamma-ray bursts (GRBs) in the unified model of short and long GRBs recently proposed by Yamazaki, Ioka, and Nakamura. Monte Carlo simulations show clear bimodal distributions, with…
We review the physics of GRB production by relativistic jets that start highly opaque near the central source and then expand to transparency. We discuss dissipative and radiative processes in the jet and how radiative transfer shapes the…
The observations of GW170817/GRB170817A have confirmed that the coalescence of a neutron-star binary is the progenitor of a short gamma-ray burst. In the standard picture of a short gamma-ray burst, a collimated highly relativistic outflow…
The observations of jet breaks in the afterglows of short gamma-ray bursts (SGRBs) indicate that the jet has a small opening angle of < 10{\deg}. The collimation mechanism of the jet is a longstanding theoretical problem. We numerically…
We derive a relation between the flux density $F_{\nu,j}$ at the light-curve break of a gamma-ray burst (GRB) afterglow and the break time $t_{j}$. The break is due to the transition from the spherical-like to jet-like evolution of the…
Recent observations suggest that gamma ray bursts (GRBs) and their afterglows are produced by highly relativistic jets emitted in supernova explosions. We have proposed that the result of the event is not just a compact object plus the…
Short $\gamma$-ray burst (sGRB) jets form in the aftermath of a neutron star merger, drill through disk winds and dynamical ejecta, and extend over four to five orders of magnitude in distance before breaking out of the ejecta. We present…
We consider a jet-disk symbiosis model to explain Gamma Ray Bursts and their afterglows. It is proposed that GRBs develop in a pre-existing jet. We consider a binary system formed by a neutron star and an O/B/WR companion in which the…
Gamma-ray bursts (GRBs) are among the most energetic events in the universe, driven by relativistic jets launched from black holes (BHs) formed during the collapse of massive stars or after the merger of two neutron stars (NSs). The jet…