Related papers: Robust Limits on Lorentz Violation from Gamma-Ray …
Lorentz symmetry is a cornerstone of modern physics, and testing its validity remains a critical endeavor. In this work, we analyze the photon time-of-flight and time-shift data from LHAASO observations of Gamma-Ray Burst GRB 221009A to…
It has been observed that photons in the prompt emission of some gamma-ray bursts (GRBs) are highly polarized. The high polarization is used by some authors to give a strict constraint on the Lorentz invariance violation (LIV). If the…
The Gamma-Ray Optical Counterpart Search Experiment (GROCSE) presents new experimental upper limits on the optical flux from gamma-ray bursts (GRBs). Our experiment consisted of a fully-automated very wide-field opto-electronic detection…
The emission process responsible for the so-called "prompt" emission of gamma-ray bursts is still unknown. A number of empirical models fitting the typical spectrum still lack a satisfactory interpretation. A few GRB spectral catalogues…
We have recently completed a search of 6 years of archival BATSE data for gamma-ray bursts (GRBs) that were too faint to activate the real-time burst detection system running onboard the spacecraft. These "non-triggered" bursts can be…
Several models of Quantum Gravity predict Lorentz Symmetry breaking at energy scales approaching the Planck scale (10^{19} GeV). With present photon data from the observations of distant astrophysical sources, it is possible to constrain…
Fermi satellite discovered that cosmological gamma-ray bursts (GRBs) are accompanied by long GeV flashes. In two GRBs, an optical counterpart of the GeV flash has been detected. Recent work suggests that the GeV+optical flash is emitted by…
The variability observed in many complex gamma-ray bursts (GRBs) is inconsistent with causally connected variations in a single, symmetric, relativistic shell interacting with the ambient material ("external shocks"). Rather, the symmetry…
We present a brief review of our recent work [1] on asymmetrically warped brane models, where the background metric is characterized by different time and space warp factors. In particular we examine the case of bulk photons and we show…
A possible subclass of gamma-ray bursts -- those with few, wide pulses, spectral lags of order one to several seconds, and soft spectra -- has been identified. Their Log[N]-Log[Fp] distribution approximates a -3/2 power-law, suggesting…
Aims: In this paper we study the main spectral and temporal properties of gamma-ray bursts (GRBs) observed by Fermi/GBM. We investigate these key properties of GRBs in the rest-frame of the progenitor and test for possible intra-parameter…
Gamma-ray bursts (GRBs) are the most powerful explosions in the universe and probe physics under extreme conditions. GRBs divide into two classes, of short and long duration, thought to originate from different types of progenitor systems.…
In a recent paper we have calculated the power density spectrum of Gamma-Ray Bursts arising from multiple shocks in a relativistic wind. The wind optical thickness is one of the factors to which the power spectrum is most sensitive,…
Gamma-ray bursts (GRB) are extremely energetic events and produce highly diverse light curves. Light curves are believed to be resulting from internal shocks reflecting the activities of the GRB central engine. Hence their temporal studies…
We report on observations of correlated behavior between the prompt gamma-ray and optical emission from GRB 080319B, which (i) strongly suggest that they occurred within the same astrophysical source region and (ii) indicate that their…
Despite the fact that quantum gravity theory still remains elusive, it is generally expected that it will bring the picture of a space-time foam at short distances leading to Lorenz Invariance Violation (LIV) manifested e.g. by energy…
Violations of both the weak equivalence principle (WEP) and Lorentz invariance can produce vacuum birefringence, which leads to an energy-dependent rotation of the polarization vector of linearly polarized emission from a given…
A quantitative theory of spectral lags for $\gamma$-ray bursts (GRBs) is given. The underlying hypothesis is that GRB subpulses are photons that are scattered into our line of sight by local concentrations of baryons that are accelerated by…
We study the variability properties at radio frequencies of the jets thought to be typical of Active Galactic Nuclei, i.e. bulk Lorentz factor \Gamma ~ 10, and incoherent synchrotron emission. We assume that the radiating electrons are…
The Gamma Ray Burst GRB920229 has four extreme and unprecedented properties; a rise in brightness with an e-folding time scale of $220 \pm 30 \mu s$, a fall in brightness with an e-folding time scale of $400 \pm 100 \mu s$, a large change…