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Young stellar objects in their pre-main sequence phase are characterized by irregular changes in brightness, generally attributed to an increase of the mass accretion rate due to various kind of instabilities occurring in the circumstellar…

Solar and Stellar Astrophysics · Physics 2022-04-06 F. Strafella , G. Altavilla , T. Giannini , A. Giunta , D. Lorenzetti , A. Nucita , A. Franco

In this paper, we continue to build support for the proposal to use gamma-ray bursts (GRBs) as standard candles in constructing the Hubble Diagram at redshifts beyond the current reach of Type Ia supernova observations. We confirm that…

High Energy Astrophysical Phenomena · Physics 2015-06-12 Jun-Jie Wei , Xue-Feng Wu , Fulvio Melia

Gamma-ray bursts (GRBs) come in two types, short and long. The distribution of logarithmic durations of long GRBs is asymmetric rather than Gaussian. Such an asymmetry, when modelled with a mixture of Gaussian distributions, requires an…

High Energy Astrophysical Phenomena · Physics 2021-08-11 Mariusz Tarnopolski

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

Observations of a long-lasting Gamma-ray burst, one that has the brightest optical counterpart yet discovered, challenge theoretical understanding of these bursts but may enhance their usefulness as cosmic probes.

High Energy Astrophysical Phenomena · Physics 2010-11-11 Jonathan Grindlay

Gamma-ray burst light curves show quite different patterns: from very simple to extremely complex. We present a temporal and spectral study of the light curves in three energy bands (2-5, 5-10, 10-26 keV) of ten GRBs detected by the Wide…

Astrophysics · Physics 2010-11-11 L. Vetere , E. Massaro , E. Costa , P. Soffitta , G. Ventura

Luminosity correlations of long Gamma-ray bursts (GRB) are extensively proposed as an effective complementarity to trace the Hubble diagram of Universe at high redshifts, which is of great importance to explore properties of dark energy.…

High Energy Astrophysical Phenomena · Physics 2017-02-22 Guo-Jian Wang , Hai Yu , Zheng-Xiang Li , Jun-Qing Xia , Zong-Hong Zhu

The optical afterglows of gamma-ray bursts can be used to probe the physics, geometry, and environments of gamma-ray bursts. In this article I discuss the how spectra and photometry can be used to constrain fireball parameters, describe…

Astrophysics · Physics 2015-06-24 S. T. Holland

Gamma-ray bursts (GRB) are powerful transient events that emit a large output of gamma rays within a few seconds. Studying these short bursts is vital for cosmological research since they originate from sources observed at large redshifts.…

High Energy Astrophysical Phenomena · Physics 2023-10-05 S. Sourav , A. Shukla , R. Dwivedi , K. Singh

Some recent studies exposed rather strong statistical evidence of in-vacuo-dispersion-like spectral lags for gamma-ray bursts (GRBs), a linear correlation between time of observation and energy of GRB particles. Those results focused on…

High Energy Astrophysical Phenomena · Physics 2017-09-05 Giovanni Amelino-Camelia , Giacomo D'Amico , Fabrizio Fiore , Simonetta Puccetti , Michele Ronco

In this article, we introduce an estimator for the asymptotic variance of the Greenwood variance estimator, where the latter is crucial for assessing the accuracy of the Kaplan-Meier survival estimator. The result indicates that the…

Statistics Theory · Mathematics 2024-06-13 J. Rodenkirchen , A. Hoyer

We discuss detailed fits of the BATSE and PVO gamma-ray burst peak-flux distributions with Friedman models taking into account possible density evolution and standard candle or power law luminosity functions. A chi-square analysis is used…

Astrophysics · Physics 2009-10-28 I. Horvath , P. Meszaros , A. Meszaros

Fast spectral variability of gamma-ray burst emission is considered for a number of events seen by the Konus-Wind experiment. The variability manifests itself as a strong correlation between instantaneous energy flux $F$ and peak energy…

Prompt {\gamma}-ray emissions from gamma-ray bursts (GRBs) exhibit a vast range of extremely complex temporal structures with a typical variability time-scale significantly short - as fast as milliseconds. This work aims to investigate the…

High Energy Astrophysical Phenomena · Physics 2011-09-28 G. Greco , R. Rosa , G. Beskin , S. Karpov , L. Romano , A. Guarnieri , C. Bartolini , R. Bedogni

We discuss possible tests of the constancy of the velocity of light using distant astrophysical sources such as gamma-ray bursters (GRBs), Active Galactic Nuclei (AGNs) and pulsars. This speculative quest may be motivated by some models of…

Astrophysics · Physics 2008-11-26 J. Ellis , K. Farakos , N. E. Mavromatos , V. Mitsou , D. V. Nanopoulos

We discuss the prospects of using Gamma Ray Bursts (GRBs) as high-redshift distance estimators, and consider their use in the study of two dark energy models, the Generalized Chaplygin Gas (GCG), a model for the unification of dark energy…

Astrophysics · Physics 2007-05-23 O. Bertolami , P. T. Silva

We investigate through dedicated numerical simulations the evolution of the soft X-ray absorption properties of a cloud surrounding a gamma-ray burst source. We show that the absorption properties of the material are strongly modified by…

Astrophysics · Physics 2009-11-07 Davide Lazzati , Rosalba Perna

A new luminosity function for galaxies can be built starting from the product of two random variables X and Y represented by a gamma variate with argument 2 >. The mean, the standard deviation and the distribution function of this new…

Astrophysics · Physics 2009-06-30 L. Zaninetti

We determined the characteristic variability time scales (\Delta t_p) of 410 bright and long GRBs, by locating the peaks of their Power Density Spectra, defined and calculated in the time domain. We found that the averaged variability time…

Astrophysics · Physics 2015-06-24 R. F. Shen , L. M. Song

In order to test the efficacy of Gamma-ray Bursts (GRB) as cosmological probes, we characterize the scatter in the correlations between six pairs of GRB observables, which have previously also been studied in arXiv:2011.14040. However, some…

High Energy Astrophysical Phenomena · Physics 2024-10-28 Sarveshkumar Purohit , Shantanu Desai
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