Related papers: The orthogonal gamma-ray burst model
We present our analysis of the multiwavelength photometric & spectroscopic observations of GRB 060210 and discuss the results in the overall context of current GRB models. All available optical data underwent a simultaneous temporal fit,…
We perform the first nonlinear and self-consistent study of the merger and ringdown of a black hole mimicking object with stable light rings. To that end, we numerically solve the full Einstein-Klein-Gordon equations governing the head-on…
We report optical observations during the first hour of the gamma-ray burst (GRB) afterglow of GRB021004. Our observation revealed the existence of a short plateau phase, in which the afterglow remained at almost constant brightness, before…
Gamma-ray bursts categorically produce broadband afterglow emission, but in some cases, emission in the optical band is dimmer than expected based on the contemporaneously observed X-ray flux. This phenomenon, aptly dubbed "optical…
The afterglows to gamma-ray bursts (GRBs) are due to synchrotron emission from shocks generated as an ultra-relativistic outflow decelerates. A forward and a reverse shock will form, however, where emission from the forward shock is well…
The afterglow of a gamma-ray burst (GRB) has been widely argued to arise from the interaction of a relativistic outflow with its ambient medium. During such an interaction, a pair of shocks are generated: a forward shock that propagates…
We analyze optical and X-ray observations of GRB 050904 obtained with TAROT and SWIFT. We perform temporal and spectral analysis of the X-ray and optical data. We find significant absorption in the early phase of the X-ray light curve, with…
Similar to the pulsar, the magnetic axis and the spin axis of the gamma-ray burst source may not lie on the same line. This may cause a ring-like jet due to collimation of the precessing magnetic axis. We analyze the tail emission from such…
In these proceedings, I discuss recent progress in understanding the nature of cosmic gamma-ray bursts (GRB), with the focus on the apparent relation of several GRBs with an energetic subclass of stellar explosions, type Ib/c core-collapse…
The afterglow emission of some gamma-ray bursts (GRBs) show a shallow decay (plateau) phase implying continuous injection of energy. The source of this energy is very commonly attributed to the spin-down power of a nascent millisecond…
Gamma-ray burst afterglows have been observed for months or even years in a few cases. It deserves noting that at such late stages, the remnants should have entered the deep Newtonian phase, during which the majority of shock-accelerated…
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…
Recent observations support the suggestion that short-duration gamma-ray bursts are produced by compact star mergers. The X-ray flares discovered in two short gamma-ray bursts last much longer than the previously proposed postmerger energy…
X-ray emission following giant flares of magnetars can be categorized into three categories of time scales (a) short term afterglow (b) medium term afterglow and (c) long term afterglow. Short term afterglow, which declines over several…
The well-sampled afterglows of gamma ray bursts (GRBs) not associated with a supernova (SN) explosion, can be scaled down to a simple dimensionless universal formula, which describes well their temporal behavior. Such SN-less GRBs include…
I show here that the time-delay between the gamma ray burst proper and the onset of the afterglow is a sensitive function of the surrounding density, going from ~10s for typical disk densities to several hours for IGM densities. Since bulk…
Long gamma-ray bursts (GRBs) from rapidly spinning black hole-torus systems may represent hypernovae or black hole-neutron star coalescence. We show that the torus may radiate gravitational radiation powered by the spin-energy of the black…
After the jet break at $t\sim 1.4$ days, the optical afterglow emission of the long-short burst GRB 060614 can be divided into two components. One is the power-law decaying forward shock afterglow emission. The other is an excess of flux in…
We present comprehensive photometric R-band observations of the fading optical afterglow of the X-Ray Flash XRF050824, from 11 minutes to 104 days after the burst. The R-band lightcurve of the afterglow resembles the lightcurves of long…
Some active galactic nuclei, microquasars, and gamma ray bursts may be powered by the electromagnetic braking of a rapidly rotating black hole. We investigate this possibility via axisymmetric numerical simulations of a black hole…