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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) prompt emission spectra are often fitted with the empirical ''Band" function, namely two power laws smoothly connected. The typical slope of the low energy (sub-MeV) power law is $\alpha_{B}\simeq -1$. In a small…

High Energy Astrophysical Phenomena · Physics 2021-08-25 M. Toffano , G. Ghirlanda , L. Nava , G. Ghisellini , M. E. Ravasio , G. Oganesyan

Using the data acquired in the Time To Spill (TTS) mode for long gamma-ray bursts (GRBs) collected by the Burst and Transient Source Experiment on board the Compton Gamma Ray Observatory (BATSE/CGRO), we have carefully measured spectral…

Astrophysics · Physics 2009-11-10 L. Chen , Y. Q. Lou , M. Wu , J. L. Qu , S. M. Jia , X. J. Yang

Gamma-ray bursts (GRBs) are the most powerful electromagnetic outbursts in the Universe and emit a vast amount of their energy in the form of gamma rays. Their duration is extremely short on cosmic timescales, but they show a wealth of time…

High Energy Astrophysical Phenomena · Physics 2025-12-11 Else Magnus , Jannes Loonen , Rose S. Stanley , Paul Coppin , Krijn D. de Vries , Nick van Eijndhoven

Intrinsic variability was searched for in arrival times of six gamma-ray bursts (GRBs) at high energies -- between 30 MeV and 2 GeV -- detected by the Fermi satellite's Large Area Telescope (LAT). The GRBs were selected from the Fermi LAT…

High Energy Astrophysical Phenomena · Physics 2024-07-31 E. Casey Aldrich , Robert J. Nemiroff

We present systematic spectral analyses of GRBs detected by the Fermi Gamma-Ray Burst Monitor (GBM) during its first two years of operation. This catalog contains two types of spectra extracted from 487 GRBs, and by fitting four different…

Millilensing of Gamma-Ray Bursts (GRBs) is expected to manifest as multiple emission episodes in a single triggered GRB with similar light-curve patterns and similar spectrum properties. Identifying such lensed GRBs could help improve…

High Energy Astrophysical Phenomena · Physics 2022-05-25 Shi-Jie Lin , An Li , He Gao , Lin Lin , Bin-Bin Zhang , Zi-Ke Liu , Jin-Hang Zou , Zhao Zhang , Huan Zhou , Zheng-Xiang Li , Lin Lan

We explain the results of Yu et al. (2015b) of the novel sharpness angle measurement to a large number of spectra obtained from the Fermi gamma-ray burst monitor. The sharpness angle is compared to the values obtained from various…

We make a detailed pulse-wise study of gamma-ray bursts (GRBs) with known redshift detected by \emph{Fermi}/Gamma Ray Burst Monitor (GBM). The sample contains 19 GRBs with 43 pulses. We find that the average peak energy is correlated to the…

High Energy Astrophysical Phenomena · Physics 2015-06-17 Rupal Basak , A. R. Rao

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

The Gamma Ray Burst (GRB) 180720B is one of the brightest events detected by the Fermi satellite and the first GRB detected by the H.E.S.S. telescope above 100 GeV. We analyse the Fermi (GBM and LAT) and Swift (XRT and BAT) data and…

High Energy Astrophysical Phenomena · Physics 2020-04-22 M. Ronchi , F. Fumagalli , M. E. Ravasio , G. Oganesyan , M. Toffano , O. S. Salafia , L. Nava , S. Ascenzi , G. Ghirlanda , G. Ghisellini

Using the gamma-ray bursts simultaneously detected by Swift/BAT and Fermi/GBM we performed a joint spectral and temporal analysis of the prompt emission data and confirm the rough correlation between the BAT-band photon index Gamma_BAT and…

High Energy Astrophysical Phenomena · Physics 2015-06-03 Francisco Virgili , Ying Qin , Bing Zhang , Enwei Liang

The long-lasting tension between the observed spectra of gamma ray bursts (GRBs) and the predicted synchrotron emission spectrum might be solved if electrons do not completely cool. Evidence for incomplete cooling was recently found in…

High Energy Astrophysical Phenomena · Physics 2019-05-15 M. E. Ravasio , G. Ghirlanda , L. Nava , G. Ghisellini

Currently, the best available probe of the early phase of gamma-ray burst (GRB) jet attributes is the prompt gamma-ray emission, in which several intrinsic and extrinsic variables determine GRB pulse evolution. Bright, usually complex…

Astrophysics · Physics 2009-11-10 J. P. Norris , J. T. Bonnell , D. Kazanas , J. D. Scargle , J. Hakkila , T. W. Giblin

Launched on June 11, 2008, the LAT instrument onboard the $Fermi$ Gamma-ray Space Telescope has provided a rare opportunity to study high energy photon emission from gamma-ray bursts. Although the majority of such events (27) have been iden…

High Energy Astrophysical Phenomena · Physics 2015-06-04 Weikang Zheng , Carl W. Akerlof , Shashi B. Pandey , Timothy A. McKay , Binbin Zhang , Bing Zhang , Takanori Sakamoto

We analyze the prompt emission of GRB 100724B and GRB 160509A, two of the brightest Gamma-Ray Bursts (GRBs) observed by Fermi at $\lesssim{\rm MeV}$ energies but surprisingly faint at $\gtrsim100\;$MeV energies. Time-resolved spectroscopy…

High Energy Astrophysical Phenomena · Physics 2018-09-19 G. Vianello , R. Gill , J. Granot , N. Omodei , J. Cohen-Tanugi , F. Longo

The study of the high-energy (MeV-GeV) part of GRBs spectrum can play a crucial role in investigating the physics of the prompt emission, but it is often hampered by low statistic and the paucity of GeV observations. In this work, we…

High Energy Astrophysical Phenomena · Physics 2024-05-29 M. E. Ravasio , G. Ghirlanda , G. Ghisellini

Macrolensing of gamma-ray bursts (GRBs) is expected to manifest as a GRB recurring with the same light curve and spectrum as a previous one, but with a different flux and a slightly offset position. Identifying such lensed GRBs may give…

High Energy Astrophysical Phenomena · Physics 2020-07-22 Björn Ahlgren , Josefin Larsson

Isolated Swift gamma-ray burst (GRB) pulses, like their higher-energy BATSE counterparts, emit the bulk of their pulsed emission as a hard-to-soft component that can be fitted by the Norris et al. (2005) empirical pulse model. This signal…

High Energy Astrophysical Phenomena · Physics 2016-01-20 Jon Hakkila , Amy Lien , Takanori Sakamoto , David Morris , James E. Neff , Timothy W. Giblin

The jet compositions of gamma-ray bursts (GRBs) are very important to understand the energy dissipation and radiation mechanisms, but it remains an open question in GRB physics. In this paper, we present a systematic analysis to search for…

High Energy Astrophysical Phenomena · Physics 2026-01-09 Xue-Zhao Chang , HouJun Lü , Zhao-Wei Du , Xing Yang , En-Wei Liang