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According to Einstein's special relativity theory, the speed of light in a vacuum is constant for all observers. However, quantum gravity effects could introduce its dispersion depending on the energy of photons. The investigation of the…

High Energy Astrophysical Phenomena · Physics 2023-08-21 Anastasia Tsvetkova , Luciano Burderi , Alessandro Riggio , Andrea Sanna , Tiziana Di Salvo

The recent association of several short gamma-ray bursts (GRBs) with early type galaxies with low star formation rate demonstrates that short bursts arise from a different progenitor mechanism than long bursts. However, since the duration…

Astrophysics · Physics 2011-09-30 Jay P. Norris , Jerry T. Bonnell

The distribution of GRB durations is bimodal, but there is little additional evidence to support the division of GRBs into short and long classes. Based on simple hardness ratios, several studies have shown a tendency for longer GRBs to…

Astrophysics · Physics 2009-11-07 W. S. Paciesas , R. D. Preece , M. S. Briggs , R. S. Mallozzi

The lag-luminosity relation for gamma-ray bursts (GRBs) is an anti-correlation between the time lag, tau_lag, which represents the delay between the arrival of hard and soft photons, and the isotropic peak luminosity, L. In this paper, we…

High Energy Astrophysical Phenomena · Physics 2012-03-30 Walid J. Azzam

In previous papers it was shown that gamma rays with characteristics similar to those of the gamma-ray bursts (GRBs) observed by astronomers may arise from suitably shaped nonuniformities in the Big Bang in a quasi-spherical Szekeres (QSS)…

General Relativity and Quantum Cosmology · Physics 2018-12-13 Andrzej Krasiński

We have investigated the bimodal distribution of the duration of BATSE gamma-ray bursts (GRBs) by analyzing light curves of 64 ms time resolution. We define the average pulse width of GRBs from the auto-correlation function of GRB profiles.…

Astrophysics · Physics 2007-05-23 Wenfei Yu , Tipei Li , Mei Wu

As is well-known, the requirement that gamma ray bursts (GRB's) be optically thin to high energy photons yields a lower limit on the Lorentz factor (\gamma) of the expansion. In this paper, we provide a simple derivation of the lower limit…

Astrophysics · Physics 2009-10-31 Yoram Lithwick , Re'em Sari

Despite more than fifty years of gamma-ray burst (GRB) observations, several questions regarding the origin of the prompt emission, particularly at high energies, remain unresolved. We present a comprehensive analysis of 35 GRBs observed by…

High Energy Astrophysical Phenomena · Physics 2025-01-22 Samanta Macera , Biswajit Banerjee , Alessio Mei , Pawan Tiwari , Gor Oganesyan , Marica Branchesi

Spectral lag of the low-energy photons with respect to the high-energy ones is a common astrophysical phenomenon (such as Gamma-ray bursts and the Crab pulsar) and may serve as a key probe to the underlying radiation mechanism. However,…

We analyze the spectral lags of a sample of bright gamma-ray burst pulses observed by CGRO BATSE and compare these with the results of high-resolution spectroscopical investigations. We find that pulses with hard spectra have the largest…

Astrophysics · Physics 2009-11-10 Felix Ryde , Dan Kocevski , Zsolt Bagoly , Nils Ryde , Attila Meszaros

The modelling of gamma-ray burst (GRB) spectra has considerable potential for increasing the understanding of these enigmatic sources. A diversity of ideas and analyses has been generated over the last two decades to explain line features…

Astrophysics · Physics 2009-10-28 M. G. Baring

Gamma-ray bursts (GRBs) usually occurs in a dense star-forming region with massive circum-burst medium. The small-angle scattering of intense prompt X-ray emission off the surrounding dust grains will have observable consequences, and…

High Energy Astrophysical Phenomena · Physics 2014-06-20 Yi-Nan Zhao , Lang Shao

It is widely believed that multiwavelength afterglows of gamma-ray bursts (GRBs) originate from relativistic blast waves. We here show that in such blast waves, a significant fraction of the energy of shock-accelerated protons would be lost…

Astrophysics · Physics 2009-11-07 Z. Li , Z. G. Dai , T. Lu

The present common view about GRB origin is related to cosmology. There are two evidences in favour of this interpretation. The first is connected with statistics, the second is based on measurements of the redshifts in the GRB optical…

Astrophysics · Physics 2009-11-06 G. S. Bisnovatyi-Kogan

Synchrotron and inverse Compton emission successfully explain the observed spectra of gamma-ray burst (GRB) afterglows. It is thought that most GRBs are products of extremely relativistic outflows and the afterglow marks the interaction of…

High Energy Astrophysical Phenomena · Physics 2023-04-04 Marcus DuPont , Andrew MacFadyen , Re'em Sari

We introduce a simple model to explain the time-reversed and stretched residuals in gamma-ray burst (GRB) pulse light curves. In this model an impactor wave in an expanding GRB jet accelerates from subluminal to superluminal velocities, or…

High Energy Astrophysical Phenomena · Physics 2019-10-02 Jon Hakkila , Robert Nemiroff

Recent observations of gamma-ray bursts (GRBs) have provided growing evidence for collimated outflows and emission, and strengthened the connection between GRBs and supernovae. If massive stars are the progenitors of GRBs, the hard photon…

Astrophysics · Physics 2009-10-31 Piero Madau , Roger D. Blandford , Martin J. Rees

Gamma-ray bursts (GRBs) are promising as sources of neutrinos and cosmic rays. In the internal shock scenario, blobs of plasma emitted from a central engine collide within a relativistic jet and form shocks, leading to particle acceleration…

High Energy Astrophysical Phenomena · Physics 2017-06-06 Mauricio Bustamante , Jonas Heinze , Kohta Murase , Walter Winter

A list of questions regarding Gamma Ray Bursts (GRBs) and Soft Gamma Repeaters (SGRs) remain unanswered within the Fireball-cone and Magnetar explosive scenarios. A persistent, thin (less than micron-sr solid angle) precessing and spinning…

Astrophysics · Physics 2014-10-13 D. Fargion , M. Grossi

The unrivalled, extreme luminosities of gamma-ray bursts (GRBs) make them the favored beacons for sampling the high redshift Universe. To employ GRBs to study the cosmic terrain -- e.g., star and galaxy formation history -- GRB luminosities…

Astrophysics · Physics 2007-05-23 J. P. Norris