相关论文: Dynamics and Afterglow Light Curves of GRB Blast W…
We investigate the dynamics and afterglow light curves of gamma-ray burst (GRB) blast waves that encounter various density structures (such as bumps, voids, or steps) in the surrounding ambient medium. We present and explain the…
The X-ray light curves of the early afterglow phase from gamma-ray bursts present a puzzling variability, including flares. The origin of these flares is still debated, and often associated with a late activity of the central engine. We…
Blast wave models are commonly used to model relativistic outflows from ultra-relativistic gamma-ray bursts (GRBs), but are also applied to lower Lorentz factor ejections from X-ray binaries (XRBs). Here we revisit the physics of blast…
We develop a model of early GRB afterglows with the dominant $X$-ray contribution from the reverse shock (RS) propagating in highly relativistic (Lorentz factor $\gamma_w \sim 10^6$) magnetized wind of a long-lasting central engine. The…
Direct multi-dimensional numerical simulation is the most reliable approach for calculating the fluid dynamics and observational signatures of relativistic jets in gamma-ray bursts (GRBs). We present a two-dimensional relativistic…
I discuss some theoretical expectations for the synchrotron emission from a relativistic blast-wave interacting with the ambient medium, as a model for GRB afterglows, and compare them with observations. An afterglow flux evolving as a…
The Gamma-Ray burst (GRB) - afterglow transition is one of the most interesting and least studied GRB phases. During this phase the relativistic ejecta begins interacting with the surrounding matter. A strong short lived reverse shock…
The second {\itshape Fermi}/LAT gamma-ray burst (GRB) catalog (2FLGC) spanning the first decade of operations by the LAT collaboration was recently released. The closure relations of the synchrotron forward shock (FS) model are not able to…
This paper performs a semi-analytic study of relativistic blast waves in the context of gamma-ray bursts (GRBs). Although commonly used in a wide range of analytical and numerical studies, the equation of state (EOS) with a constant…
In the fireball model, it is more physically realistic that gamma-ray burst (GRB) ejecta have a range of bulk Lorentz factors (assuming $M\propto \Gamma^{-s}$). The low Lorentz factor part of the ejecta will catch up with the high Lorentz…
We analyze in detail the hydrodynamics and afterglow emission of an ultrarelativistic blast wave when it expands in a density-jump medium. Such a medium is likely to appear in the vicinity of gamma-ray bursts (GRBs) associated with massive…
The X-ray light-curves of 9 Swift XRT afterglows (050126, 050128, 050219A, 050315, 050318, 050319, 050401, 050408, 050505) display a complex behaviour: a steep t^{-3.0 \pm 0.3} decay until ~400 s, followed by a significantly slower…
The origin of the X-ray plateau phase observed in a large fraction of gamma-ray burst afterglows remains debated. We present a novel analytic framework for the hydrodynamics of ultra-relativistic, radially stratified outflows interacting…
We study the morphology of gamma-ray burst (GRB) afterglows viewed off-axis using a simplified analytical model. We consider steep jets, which are expected to be the most common type. These jets, characterized by steep lateral gradients in…
The recently discovered GRB afterglow is believed to be described reasonably well by synchrotron emission from a slowing down relativistic shell that collides with an external medium. To compare theoretical models with afterglow…
To study the ejecta property dependence of the gamma-ray burst (GRB) afterglow, we carry out spherically symmetrical one-dimensional special relativistic magneto-hydrodynamic simulations of magnetized outflows with an adaptive mesh…
We present optical and near-infrared photometric observations of GRB 191016 with the COATLI, DDOTI and RATIR ground-based telescopes over the first three nights. We present the temporal evolution of the optical afterglow and describe 5…
The most luminous GRBs can be explained in terms of models involving stellar mass central engines only if the ejecta are beamed. As was pointed out by Rhoads, the dynamics of the blast wave, formed by the beamed ejecta sweeping the external…
We consider fireball models where the ejecta have a range of bulk Lorentz factors, so that the inner (lower $\Gamma$) parts may carry most of the mass, or even most of the energy. The outer shock and contact discontinuity decelerate as the…
Explosions of massive stars are believed to be the source of a significant fraction of gamma-ray bursts (GRBs). If this is indeed the case, then the explosion blast wave propagates into a complex density structure, composed of a stellar…