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Gamma-ray bursts (GRBs) as the most energetic explosions in the modern universe have been studied over half a century, but the physics of the particle acceleration and radiation responsible for their observed spectral behaviors are still…

High Energy Astrophysical Phenomena · Physics 2024-07-22 Cheng-Feng Peng , Rui-Jing Lu , Wen-Qiang Liang , Zhe-geng Chen

The lag-luminosity relation (LLR) provides a way of estimating GRB luminosity by measuring the spectral lags between different energy bands. We want to understand the origin of the LLR and test its validity. This appears especially…

Astrophysics · Physics 2009-11-13 Mimoza Hafizi , Robert Mochkovitch

The radiation released at the transparency radius of an ultrarelativistic flow can account for the observed properties of gamma-ray bursts (GRBs) provided that sufficient energy is dissipated in the sub-photospheric region. Here, I…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Dimitrios Giannios

Although the Fermi mission has increased our knowledge of gamma-ray AGN, many questions remain, such as the site of gamma-ray production, the emission mechanism, and the factors that govern the strength of the emission. Using data from a…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-30 E. Nieppola , M. Tornikoski , E. Valtaoja , J. León-Tavares , T. Hovatta , A. Lähteenmäki , J. Tammi

As so far, the redshift of Gamma-ray bursts (GRBs) can extend to $z\sim 8$ which makes it as a complementary probe of dark energy to supernova Ia (SN Ia). However, the calibration of GRBs is still a big challenge when they are used to…

Cosmology and Nongalactic Astrophysics · Physics 2015-05-19 Lixin Xu

Simple hardness ratios are found to be a good estimator for the spectral peak energy in Gamma-Ray Bursts (GRBs). Specifically, a high correlation strength is found between the $\nu F_{\nu}$ peak in the spectrum of BATSE GRBs, $\epo$, and…

High Energy Astrophysical Phenomena · Physics 2018-02-05 Amir Shahmoradi , Robert J. Nemiroff

We estimate the luminosity evolution and formation rate for over 900 GRBs by using redshift and luminosity data calculated by Band, Norris, $&$ Bonnell (2004) via the lag-luminosity correlation. By applying maximum likelihood techniques, we…

Astrophysics · Physics 2009-11-11 Daniel Kocevski , Edison Liang

Several correlations among Gamma-Ray Bursts (GRBs) quantities, both in the prompt and afterglow emissions, have been established during the last decades, thus enabling the standardization of GRBs as cosmological probes. Since GRBs are…

Cosmology and Nongalactic Astrophysics · Physics 2024-10-29 Giada Bargiacchi , Maria Giovanna Dainotti , Salvatore Capozziello

The Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope observatory is a pair conversion telescope sensitive to gamma-rays over more than four energy decades, between 20 MeV and more than 300 GeV. Acting in synergy with the…

High Energy Astrophysical Phenomena · Physics 2019-08-14 Nicola Omodei

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

The First \fermi-LAT Catalog of Sources Above 10 GeV reported evidence of pulsed emission above 25 GeV from 12 pulsars, including the Vela pulsar, which showed evidence of pulsation at $>37$ GeV energy bands. Using 62 months of \fermi-LAT…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Gene C. K. Leung , J. Takata , C. W. Ng , A. K. H Kong , P. H. T. Tam , C. Y. Hui , K. S. Cheng

This manuscript presents a multilevel analysis of gamma-ray bursts (GRBs). We focus on the plateau phase, which is often observed in the light curves (LCs) of GRBs. We discuss its observational properties and then thoroughly examine…

High Energy Astrophysical Phenomena · Physics 2025-04-09 Aleksander Ł. Lenart , Maria G. Dainotti , Nikita Khatiya , Dhruv Bal , Dieter H. Hartmann , Nissim Fraija , Bing Zhang

Based on the experience gained during the four and a half years of the mission, the Fermi -LAT collaboration has undertaken a comprehensive revision of the event-level analysis going under the name of Pass 8. Although it is not yet…

At high-energy gamma-rays (>100 MeV) the Large Area Telescope (LAT) on the Fermi satellite already detected more than 145 rotation-powered pulsars (RPPs), while the number of pulsars seen at soft gamma-rays (20 keV - 30 MeV) remained small.…

High Energy Astrophysical Phenomena · Physics 2015-06-24 L. Kuiper , W. Hermsen

From the launch of the Fermi Gamma-ray Space Telescope to July 9, 2010, the Gamma-ray Burst Monitor (GBM) has detected 497 probable GRB events. Twenty-two of these satisfy the simultaneous requirements of an estimated burst direction within…

High Energy Astrophysical Phenomena · Physics 2015-05-20 C. W. Akerlof , W. Zheng , S. B. Pandey , T. A. McKay

Several trends have been identified in the prompt gamma-ray burst (GRB) emission: e.g. hard-to-soft evolution, pulse width evolution with energy, time lags, hardness-intensity/-fluence correlations. Recently Fermi has significantly extended…

High Energy Astrophysical Phenomena · Physics 2015-06-19 Z. Bosnjak , F. Daigne

Recent studies have found that the spectral evolution of pulses within gamma-ray bursts (GRBs) is consistent with simple radiative cooling. Perhaps more interesting was a report that some bursts may have a single cooling rate for the…

Astrophysics · Physics 2009-10-30 A. Crider , E. P. Liang , R. D. Preece

A temporal analysis has been performed on a sample of 100 bright gamma-ray bursts (GRBs) with T90<2s from the BATSE current catalog. The GRBs were denoised using a median filter and subjected to an automated pulse selection algorithm as an…

Astrophysics · Physics 2009-11-07 S. McBreen , F. Quilligan , B. McBreen , L. Hanlon , D. Watson

Several correlations among Gamma Ray Burst (GRB) observables with available redshifts have been recently identified. Proper evaluation and calibration of these correlations may facilitate the use of GRBs as standard candles constraining the…

Astrophysics · Physics 2010-03-19 S. Basilakos , L. Perivolaropoulos

We perform Monte Carlo simulations to study Ep-Eiso correlation in the context of a multiple subjet model (or inhomogeneous jet model) for gamma-ray bursts (GRBs), X-ray--rich GRBs (XRRs), and X-ray flashes (XRFs). For a single subjet, we…

Astrophysics · Physics 2009-11-24 Kenji Toma , Ryo Yamazaki , Takashi Nakamura
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