相关论文: The Beaming Factor and Other Open Questions In GRB…

We investigate the shape of the jet break in within-beam gamma-ray burst (GRB) optical afterglows for various lateral jet structure profiles. We consider cases with and without lateral spreading and a range of inclinations within the jet…

I discuss here the progress made in the last decade on few of the key open problems in GRB physics. These include: (1) the nature of GRB progenitors, and the outliers found to the collapsar/merger scenarios; (2) Jet structures, whose…

Herein I present numerical calculations of lightcurves of homogeneous and structured afterglows with various lateral expansion rates as seen from any vantage point. Such calculations allow for direct simulation of observable quantities for…

We present an analytical approach to the dynamical evolution of fireballs or axially symmetric jets expanding into an external medium, with application to Gamma-Ray Burst remnants. This method leads to numerical calculations of fireball…

A two-component jet model is proposed to explain the unusual afterglow of GRB 070419A. Regarding the optical light curve, a wide "jet" with an opening angle of > 30-40 degrees is assumed to produce the late shallow decay, while the three…

Gamma-ray bursts (GRBs), associated with the collapse of massive stars or the collisions of compact objects, are the most luminous events in our universe. However, there is still much to learn about the nature of the relativistic jets…

As the most energetic explosions in the Universe, gamma-ray bursts (GRBs) are commonly believed to be generated by relativistic jets. Recent observational evidence suggests that the jets producing GRBs are likely to have a structured…

For gravitational wave (GW) detected neutron star mergers, one of the leading candidates for electromagnetic (EM) counterparts is the afterglow from an ultra-relativistic jet. Where this afterglow is observed, it will likely be viewed…

We model the radio, optical, and X-ray emission for the afterglows of GRB 980703, 990123, 990510, and 991216, within the framework of relativistic jets, to determine their physical parameters. The models that yield acceptable fits to the…

We use high--quality, multi-band observations of Swift GRB120404A, from gamma-ray to radio frequencies, together with the new hydrodynamics code of van Eerten et al. (2012) to test the standard synchrotron shock model. The evolution of the…

We present a complete sample of 29 GRBs for which it has been possible to determine temporal breaks (or limits) from their afterglow light curves. We interpret these breaks within the framework of the uniform conical jet model,…

Recent observational and theoretical studies have raised the possibility that the collimated outflows in gamma-ray burst (GRB) sources have two distinct components: a narrow (opening half-angle $\theta_{\rm n}$), highly relativistic…

We report on optical, near-infrared and centimeter radio observations of GRB000418 which allow us to follow the evolution of the afterglow from 2 to 200 days after the gamma-ray burst. In modeling these broad-band data, we find that an…

Gamma-ray Burst (GRB) collimation has been inferred with the observations of achromatic steepening in GRB light curves, known as jet breaks. Identifying a jet break from a GRB afterglow lightcurve allows a measurement of the jet opening…

A strong correlation is reported between gamma-ray burst (GRB) pulse lags and afterglow jet-break times for the set of bursts (seven) with known redshifts, luminosities, pulse lags, and jet-break times. This may be a valuable clue toward…

Gamma-ray bursts (GRBs) are luminous stellar explosions characterized by the ejection of relativistic jets. This work proposes a novel paradigm to study these GRB jets. By analyzing the timing information of prompt pulses and X-ray flares,…

We present a systematic temporal and spectral study of all Swift-XRT observations of GRB afterglows discovered between 2005 January and 2007 December. After constructing and fitting all light curves and spectra to power-law models, we…

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…

The discovery of GRB 170817A, the first unambiguous off-axis short gamma-ray burst arising from a neutron star merger, has challenged our understanding of the angular structure of relativistic jets. Studies of the jet propagation usually…

I review gamma-ray burst optical/multiwavelength afterglow observations since 1997, when the first counterparts to GRBs were discovered. I discuss what we have learned from multiwavelength observations of GRB afterglows in relation to the…