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We consider the properties of a hyperaccretion model for gamma-ray bursts (GRBs) at the late time when the mass supply rate is expected to decrease with time. We point out that the region in the vicinity of the accretor and the accretor…

Astrophysics · Physics 2011-02-11 Daniel Proga , Bing Zhang

We have developed a computer model to calculate gamma ray burst (GRB) light curves and efficiencies from the interaction of a single, thin blast wave with clouds in the external medium. Large amplitude, spiky variability occurs when the…

Astrophysics · Physics 2009-10-31 Charles D. Dermer , Kurt E. Mitman

The origin of prompt emission in GRBs is not yet well understood. The simplest and most popular model is Synchrotron, Self-Compton (SSC) emission produced by internal shocks inside an ultra-relativistic jet. However, recent observations of…

Cosmology and Nongalactic Astrophysics · Physics 2015-03-17 Houri Ziaeepour , Brian Gardner

We present the results of our study of the variability time scales of a sample of 27 long Swift Gamma-Ray Bursts (GRBs) with known redshifts. The variability time scale can help our understanding of fundamental GRB parameters such as the…

High Energy Astrophysical Phenomena · Physics 2009-06-18 T. N. Ukwatta , K. S. Dhuga , W. C. Parke , T. Sakamoto , C. B. Markwardt , S. D. Barthelmy , D. F. Cioffi , A. Eskandarian , N. Gehrels , L. Maximon , D. C. Morris

We have proposed three paradigms for the theoretical interpretation of gamma-ray bursts (GRBs). (1) The relative space-time transformation (RSTT) paradigm emphasizes how the knowledge of the entire world-line of the source from the moment…

Astrophysics · Physics 2009-11-07 R. Ruffini , C. L. Bianco , P. Chardonnet , F. Fraschetti , S. -S. Xue

We consider a speculative model for gamma-ray bursts (GRB), which predicts that the total kinetic energy in the ejected matter is less than the total energy in the gamma rays. There is also secondary energy in X-rays, which are emitted…

Astrophysics · Physics 2010-11-15 Saul Barshay , Georg Kreyerhoff

Detecting high-z GRBs is important for constraining the GRB formation rate, and tracing the history of re-ionization and metallicity of the universe. Based on the current sample of GRBs detected by Swift with known redshifts, we…

Astrophysics · Physics 2009-06-23 T. N. Ukwatta , T. Sakamoto , M. Stamatikos , N. Gehrels , K. S. Dhuga

We investigate a "hypernova" model for gamma-ray bursts (GRBs), i.e., massive C+O star model with relativistic jets. In this model, non-thermal precursors can be produced by the "first" relativistic shell ejected from the star. Main GRBs…

Astrophysics · Physics 2009-11-13 Hideyuki Umeda , Nozomu Tominaga , Keiichi Maeda , Ken'ichi Nomoto

Gamma-ray bursts (GRBs) show a dramatic pulse structure that requires bulk relativistic motion, but whose physical origin has remained murky. We focus on a hot, magnetized jet that is emitted by a black hole and interacts with a confining…

High Energy Astrophysical Phenomena · Physics 2014-06-23 Christopher Thompson , Ramandeep Gill

Sorted by the photon fluences of short Gamma-ray Bursts (SGRBs) detected by the Fermi- Gamma Ray Burst Monitor (GBM), nine brightest bursts are selected to perform a comprehensive analysis. All GRB lightcurves are fitted well by 1 to 3…

High Energy Astrophysical Phenomena · Physics 2022-03-10 Peng-Wei Zhao , Qing-Wen Tang

We discuss the preliminary results of spectral analysis simulations involving anticipated correlated multi-wavelength observations of gamma-ray bursts (GRBs) using Swift's Burst Alert Telescope (BAT) and the Gamma-Ray Large Area Space…

Astrophysics · Physics 2009-11-13 Michael Stamatikos , Takanori Sakamoto , David L. Band

We examine millisecond magnetars as central engines of Gamma Ray Bursts' (GRB) prompt emission. Using the proto-magnetar wind model of Metzger et al. 2011, we estimate the temporal evolution of the magnetization and power injection at the…

High Energy Astrophysical Phenomena · Physics 2017-10-12 Paz Beniamini , Dimitrios Giannios , Brian D. Metzger

The emission mechanism of the gamma-ray bursts (GRBs) is still a matter of debates. The standard synchrotron energy spectrum of cooling electrons F_E ~ E^{-1/2} is much too soft to account for the majority of the observed spectral slopes.…

Astrophysics · Physics 2009-11-10 Boris E. Stern , Juri Poutanen

Forward shocks caused by the interaction between a relativistic blast wave and the circum-burst medium are thought to be responsible for the afterglow emission in Gamma-Ray Bursts (GRBs). We consider the hydrodynamics of a spherical…

High Energy Astrophysical Phenomena · Physics 2015-06-12 L. Nava , L. Sironi , G. Ghisellini , A. Celotti , G. Ghirlanda

Most of proposed models of cosmological gamma-ray bursts (GRBs) are associated to gravitational collapses of massive stars, and hence evolution of the GRB rate, which is crucially important in GRB intensity distribution analysis, is…

Astrophysics · Physics 2007-05-23 Tomonori TOTANI

It has been suggested that the prompt emission in gamma-ray bursts (GRBs) could be described by radiation from the photosphere in a hot fireball. Such models must be tested by directly fitting them to data. In this work we use data from the…

High Energy Astrophysical Phenomena · Physics 2019-01-30 Björn Ahlgren , Josefin Larsson , Erik Ahlberg , Christoffer Lundman , Felix Ryde , Asaf Pe'er

Gamma Ray Bursts (GRBs) show evidence of different light curves, duration, afterglows, host galaxies and they explode within a wide redshift range. However, their spectral energy distributions (SEDs) appear to be very similar showing a…

High Energy Astrophysical Phenomena · Physics 2015-05-18 F. Massaro , J. E. Grindlay , A. Paggi

We update predictions for the gravitational wave (GW) signal from a strongly supercooled phase transition in an illustrative classically conformal U(1)$_{B-L}$ model. We implement $\propto \gamma^2$ scaling of the friction on the bubble…

Cosmology and Nongalactic Astrophysics · Physics 2020-11-25 John Ellis , Marek Lewicki , Ville Vaskonen

Gamma-ray bursts (GRBs) rank among the most powerful astrophysical phenomena, characterized by complex and highly variable prompt emission light curves that reflect the dynamics of their central engines. In this work, we analyze a sample of…

High Energy Astrophysical Phenomena · Physics 2026-01-28 Ruo-Yu Guan , Fei-Fei Wang , Yuan-Chuan Zou

Over half a century from the discovery of gamma-ray bursts (GRBs), the dominant radiation mechanism responsible for their bright and highly variable prompt emission remains poorly understood. Spectral information alone has proven…

High Energy Astrophysical Phenomena · Physics 2021-10-20 Ramandeep Gill , Merlin Kole , Jonathan Granot