Related papers: Gamma-ray burst early optical afterglows: implicat…
Gamma-ray bursts (GRBs) are the most electromagnetically luminous cosmic explosions. They are powered by collimated streams of plasma (jets) ejected by a newborn stellar-mass black hole or neutron star at relativistic velocities (near the…
Well-sampled optical lightcurves of 146 gamma-ray bursts (GRBs) are complied from the literature. Multiple optical emission components are extracted with power-law function fits to these lightcurves. We present a systematical analysis for…
Before 2004, nearly all GRB afterglow data could be understood in the context of the external shocks model. This situation has changed in the past two years, when it became clear that some afterglow components should be attributed to the…
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 report on BeppoSAX simultaneous X- and gamma-ray observations of the bright GRB 990123. We present the broad-band spectrum of the prompt emission, including optical, X- and gamma-rays, confirming the suggestion that the emission…
The observations of gamma-ray bursts (GRBs) such as 980425, 031203 and 060218, with luminosities much lower than those of other classic bursts, lead to the definition of a new class of GRBs -- low-luminosity GRBs. The nature of the outflow…
Whether gamma-ray bursts are highly beamed or not is a very important question, since it has been pointed out that the beaming will lead to a sharp break in the afterglow light curves during the ultra-relativistic phase, with the breaking…
The optical and gamma-ray observations of GRB 080319B allow us to determine a fairly complete physical picture for this remarkable burst. The data indicate that the prompt optical and gamma-ray photons were produced at the same location but…
Long gamma-ray bursts (GRBs) are characterized by a brief gamma-ray flash followed by a longer-lasting multiwavelength afterglow. The basic mechanism is largely understood, and the early afterglow evolution often shows complex features that…
We discuss the optical and radio early afterglow emission of the reverse shock that crosses a baryonic ejecta as it interacts with the external interstellar medium (ISM). We show that the peak of the optical flash divides the light curve of…
We report on the BeppoSAX data analysis of the afterglow of Gamma-Ray Burst (GRB) 990123, one of the brightest GRBs detected by BeppoSAX. Mainly due to its exceptional brightness, this is the only source for which the Wide Field Cameras…
We present a multiwavelength analysis of 63 Gamma-Ray Bursts observed with the world's three largest robotic optical telescopes, the Liverpool and Faulkes Telescopes (North and South). Optical emission was detected for 24 GRBs with…
The central engine of gamma-ray bursts (GRBs) is believed to eject double-sided ultra-relativistic jets. For an observed GRB, one of the twin jets should point toward us, and is responsible for the prompt gamma-ray and subsequent afterglow…
Highly magnetized, rapidly rotating compact objects are widely argued as central energy sources of $\gamma$-ray bursts (GRBs). After the GRB, such a magnetar-like object may directly lose its rotational energy through some…
We report on the BeppoSAX and multiwavelength data analysis of the afterglow of Gamma-Ray Burst (GRB) 990123. Mainly due to its exceptional brightness, this is the only source for which the Wide Field Cameras have allowed an early detection…
Within the framework of the external shock model of gamma-ray bursts (GRBs) afterglows, we perform a morphological analysis of the early optical lightcurves to directly constrain model parameters. We define four morphological types, i.e.…
Motivated by GW170817 we examine constraints that observations put on the angular structure of long gamma-ray burst (GRB) jets. First, the relatively narrow observed distribution of $E_{X}/E_{\gamma}$ (the isotropic equivalent early X-ray…
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…
Gamma ray burst (GRB) afterglow light curves have the potential to inform us about presently unobserved stages in the aftermath of a neutron star merger. Using numerical simulations of short GRB afterglows we obtain an approximate…
GRB 080503, detected by Swift, belongs to the class of bursts whose prompt phase consists of an initial short spike followed by a longer soft tail. It did not show any transition to a regular afterglow at the end of the prompt emission but…