相关论文: Early afterglows from radially structured outflows…

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…

A number of correlations between observables have been found to exist for gamma-ray burst (GRB) afterglows, linking ejecta energy to prompt and afterglow energy release and linking early stage optical and X-ray luminosity to the end times…

We study prompt optical emission from reverse shocks in the wind-type gamma-ray bursts. The emission is evaluated in both the thick and thin shell regimes. We discuss the angular time delay effect and the post-shock evolution of the…

We discuss the reference time t_0 of afterglow light curves in the context of the standard internal-external shock model. The decay index of early afterglow is very sensitive to the reference time one chooses. In order to understand the…

Early optical afterglows have been observed from GRB 990123, GRB 021004, and GRB 021211, which reveal rich emission features attributed to reverse shocks. It is expected that Swift will discover many more early afterglows. Here we…

In the internal shock scenario for GRBs we expect some fraction of the energy of the burst to be carried by slow moving shells that were ejected at late times. These slow shells collide with faster moving outer shells when the outer shells…

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 shock model has successfully explained the observed behaviors of afterglows from long gamma-ray bursts (GRBs). Here we use it to investigate the so-called early afterglows from short GRBs, which arises from blast waves that are not…

We study the early afterglows of gamma-ray bursts produced by geometrically thick fireballs, following the development of the external shock as energy is continually supplied to the shocked material. We study the dependence of the early…

When a cold shell sweeps up the ambient medium, a forward shock and a reverse shock will form. We analyze the reverse-forward shocks in a wind environment, including their dynamics and emission. An early afterglow is emitted from the…

We propose to explain the recent observations of GRB early X-ray afterglows with SWIFT by the dissipation of energy in the reverse shock which crosses the ejecta as it is decelerated by the burst environment. We compute the evolution of the…

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 early X-ray afterglow of gamma-ray bursts revealed by Swift carried many surprises. We focus in this paper on the plateau phase whose origin remains highly debated. We confront several newly discovered correlations between prompt and…

The prompt localization of gamma-ray burst (GRB) 050525A by {\em Swift} allowed the rapid follow-up of the afterglow. The observations revealed that the optical afterglow had a major rebrightening starting at $\sim 0.01$ days and ending at…

We calculate the expected spectrum and light curves of the early afterglow. For short GRBs the peak of the afterglow will be delayed, typically, by a few dozens of seconds after the burst. The x-ray and gamma-ray characteristics of this…

The afterglow of a gamma-ray burst (GRB) is commonly thought to be due to continuous deceleration of a relativistically expanding fireball in the surrounding medium. Assuming that the expansion of the fireball is adiabatic and that the…

The peak time of optical afterglow may be used as a proxy to constrain the Lorentz factor Gamma of the gamma-ray burst (GRB) ejecta. We revisit this method by including bursts with optical observations that started when the afterglow flux…

In the dynamical models of gamma-ray burst (GRB) afterglows, the uniform assumption of the shocked region is known as provoking total energy conservation problem. In this work we consider shocks originating from magnetized ejecta, extend…

The standard afterglow model neglects the presence of the GRB prompt radiation ahead of the blast wave. In fact, the blast wave is dramatically influenced by the leading gamma-ray front which preaccelerates the ambient medium and loads it…

GRB021211 was first detected by HETE II and its early afterglow has been observed. There is a break in its afterglow light curve at about 12 minutes after the bursts, before the break the optical flux decays with a power-law index of about…