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We invert directly the redshift - luminosity distribution of observed long Swift GRBs to obtain their rate and luminosity function. Our best fit rate is described by a broken power law that rises like (1+z)^2.1{+0.5-0.6} for 0<z<3 and…

High Energy Astrophysical Phenomena · Physics 2010-08-11 David Wanderman , Tsvi Piran

The realization that the total energy of GRBs is correlated with their jet break angles motivates the search for a similar relation between the peak luminosity, $L$, and the jet break angles, $L\propto\theta^{-2}$. Such a relation implies…

Astrophysics · Physics 2011-06-21 D. Guetta , T. Piran , E. Waxman

We present the optical luminosity function (LF) of gamma-ray bursts (GRBs) estimated from a uniform sample of 58 GRBs from observations with the Robotic Optical Transient Search Experiment III (ROTSE-III). Our GRB sample is divided into two…

We present an analysis of the Internal Shock Model of GRBs, where gamma-rays are produced by internal shocks within a relativistic wind. We show that observed GRB characteristics impose stringent constraints on wind and source parameters.…

Astrophysics · Physics 2009-10-31 D. Guetta , M. Spada , E. Waxman

The intriguing observations of Swift/BAT X-ray flash XRF 060218 and the BATSE-BeppoSAX gamma-ray burst GRB 980425, both with much lower luminosity and redshift compared to other observed bursts, naturally lead to the question of how these…

Astrophysics · Physics 2009-11-13 Francisco Virgili , Enwei Liang , Bing Zhang

We attempt to constrain the luminosity function of Gamma Ray Bursts (GRBs) from the observed number count--flux relation and the afterglow redshift data. We assume three classes of luminosity functions for our analysis: (a) Log-normal…

Astrophysics · Physics 2009-11-07 Shiv Sethi , S. G. Bhargavi

The determination of luminosity function (LF) of gamma-ray bursts (GRBs) is of an important role for the cosmological applications of the GRBs, which is however hindered seriously by some selection effects due to redshift measurements. In…

High Energy Astrophysical Phenomena · Physics 2013-10-17 Wei-Wei Tan , Xiao-Feng Cao , Yun-Wei Yu

Using the sample of long Gamma-ray bursts (GRBs) detected by Swift-BAT before June 2007, we measure the cumulative distribution of the peak photon fluxes (log N - log P) of the Swift bursts. Compared with the BATSE sample, we find that the…

Astrophysics · Physics 2011-02-11 Xinyu Dai

The accumulation of {\it Swift} observed gamma-ray bursts (GRBs) gradually makes it possible to directly derive a GRB luminosity function (LF) from observational luminosity distribution, where however two complexities must be involved as…

High Energy Astrophysical Phenomena · Physics 2012-07-11 Xiao-Feng Cao , Yun-Wei Yu , K. S. Cheng , Xiao-Ping Zheng

The nature of the `inner engine' that accelerate and collimate the relativistic flow at the cores of GRBs is the most interesting current puzzle concerning GRBs. Numerical simulations have shown that the internal shocks' light curve…

Astrophysics · Physics 2009-11-07 E. Nakar , T. Piran

According to the internal-external shocks model for $\gamma $-ray bursts (GRBs), the GRB is produced by internal shocks within a relativistic flow while the afterglow is produced by external shocks with the ISM. We explore the early…

Astrophysics · Physics 2008-11-26 Re'em Sari , Tsvi Piran

In the internal shock scenario for GRBs we expect some fraction of the energy of the burst to be carried by slow moving shells that were ejected at late times. These slow shells collide with faster moving outer shells when the outer shells…

Astrophysics · Physics 2009-10-31 Pawan Kumar , Tsvi Piran

If Gamma-ray Bursts (GRBs) are generally associated with supernovae like 1998bw, a relatively wide intrinsic luminosity function is implied, which indicates the existence of a large amount of undetected dim bursts, and a much higher…

Astrophysics · Physics 2007-05-23 H. Che

We review five studies of the gamma-ray burst (GRB) luminosity function that are based on one or more of the proposed luminosity criteria, i.e., variability, spectral lag and spectral hardness. A comparison between the resulting luminosity…

Astrophysics · Physics 2007-05-23 Maarten Schmidt

We have analyzed the prompt and afterglow characteristics of the intermediate luminosity burst ``GRB 210210A". Our prompt emission analysis indicates that GRB 210210A is among the softest long GRBs detected by the Swift-BAT. The…

High Energy Astrophysical Phenomena · Physics 2025-07-10 Rahul Gupta , A. K. Ror , S. B. Pandey , J. Racusin , M. Moss , A. Aryan , N. Klingler , A. J. Castro-Tirado

We examine the width of the gamma-ray burst (GRB) luminosity function through the distribution of GRB peak count rates, C$_{\rm{peak}}$, as detected by BATSE (\cite{batse:93}). In the context of galactic corona spatial distribution models,…

Astrophysics · Physics 2009-10-22 Andrew Ulmer , Ralph A. M. J. Wijers

We use the BD2 sample of gamma-ray bursts (GRBs) based on 5.9 years of BATSE DISCLA data with a variety of models of the luminosity function to derive characteristic GRB luminosities, space densities and redshift distributions. Previously…

Astrophysics · Physics 2009-10-31 Maarten Schmidt

The determination of the luminosity function (LF) in gamma ray bursts (GRBs) depends on the adopted cosmology, each one characterized by its corresponding luminosity distance. Here we analyse three cosmologies: the standard cosmology, the…

Cosmology and Nongalactic Astrophysics · Physics 2016-11-08 L. Zaninetti

The radiative process responsible for gamma-Ray Burst (GRB) prompt emission has not been identified yet. If dominated by fast-cooling synchrotron radiation, the part of the spectrum immediately below the $\nu F_\nu$ peak energy should…

High Energy Astrophysical Phenomena · Physics 2017-09-20 Gor Oganesyan , Lara Nava , Giancarlo Ghirlanda , Annalisa Celotti

The structure of Gamma Ray Burst (GRB) jets impacts on their prompt and afterglow emission properties. The jet of GRBs could be uniform, with constant energy per unit solid angle within the jet aperture, or it could instead be structured,…

High Energy Astrophysical Phenomena · Physics 2015-06-22 A. Pescalli , G. Ghirlanda , O. S. Salafia , G. Ghisellini , F. Nappo , R. Salvaterra
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