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In almost any scenario for 'cosmological' gamma-ray bursts (and in many models where they originate in our own Galaxy), the initial energy density is so large that the resulting relativistic plasma expands with $v\sim c$ producing a blast…

Astrophysics · Physics 2009-10-22 P. Meszaros , M. J. Rees

We have averaged bright BATSE bursts to uncover the average overall temporal and spectral evolution of gamma-ray bursts (GRBs). We align the temporal structure of each burst by setting its duration to a standard duration, which we call…

Astrophysics · Physics 2007-05-23 E. E. Fenimore

We have studied the averaged power density spectra (PDSs) of two classes of long-duration gamma-ray bursts in the recent classification by Balastegui et al.(2001) based on neural network analysis. Both PDSs follow a power law over a wide…

Astrophysics · Physics 2014-03-11 R. F. Shen , L. M. Song

In this paper we present the observations performed by the BeppoSAX Gamma-Ray Burst Monitor (GRBM) and Wide Field Cameras (WFC) of GB960720. We derive a precise localization (3 arcmin radius) and fast broad band (2-700 keV) spectral…

The spectral evolution characteristics of the prompt emission in gamma-ray bursts (GRBs) have been extensively studied, but detailed investigations of spectral evolution in a GRB flare remain lacking. In this work, we present the first…

Recent advances in fitting prompt emission spectra in gamma-ray bursts (GRBs) are boosting our understanding of the still elusive origin of this radiation. These progresses have been possible thanks to a more detailed analysis of the…

High Energy Astrophysical Phenomena · Physics 2018-02-07 Lara Nava , Gor Oganesyan , Maria E. Ravasio , Lorenzo Amati , Giancarlo Ghirlanda , Paul O'Brien , Julian P. Osborne , Richard Willingale

Characteristic variability timescales in blazar gamma-ray light curves can provide insight into the physical processes responsible for the gamma-ray variability. The power spectral density (PSD) is capable of revealing such timescales,…

High Energy Astrophysical Phenomena · Physics 2019-11-06 James L. Ryan , Aneta Siemiginowska , Malgosia Sobolewska , Jonathan Grindlay

We compare population synthesis results for inner and outer magnetosphere emission models with the various characteristics measured in the first LAT pulsar catalogue for both the radio-loud and radio-weak or radio-quiet gamma-ray pulsars.…

High Energy Astrophysical Phenomena · Physics 2015-05-27 Marco Pierbattista , Isabelle Grenier , Alice Harding , Peter L. Gonthier

We present detailed analysis of the gamma-ray flux variability and spectral properties of the five radio-loud narrow line Seyfert 1 (RL-NLSy1) galaxies, detected by the Large Area Telescope onboard the Fermi Gamma-ray Space Telescope,…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Vaidehi S. Paliya , C. S. Stalin , C. D. Ravikumar

We demonstrate that the rapid spectral variability of prompt GRBs is an inherent property of radiation emitted from shock-generated, highly anisotropic small-scale magnetic fields. We interpret the hard-to-soft evolution and the correlation…

Astrophysics · Physics 2009-11-11 Mikhail V. Medvedev

Although it is generally assumed that there are two dominant classes of gamma-ray bursts (GRB) with different typical durations, it has been difficult to unambiguously classify GRBs as short or long from summary properties such as duration,…

High Energy Astrophysical Phenomena · Physics 2023-03-15 Charles L. Steinhardt , William J. Mann , Vadim Rusakov , Christian K. Jespersen

We report on bursts from the Soft Gamma-Ray Repeater SGR 1806--20 detected with INTEGRAL in October 2003, during a period of moderate activity of the source. The spectral and temporal properties of 21 short bursts are consistent with those…

Astrophysics · Physics 2016-08-30 D. Gotz , S. Mereghetti , I. F. Mirabel , K. Hurley

The origin of the gamma-ray burst (GRB) prompt emission still defies explanation, in spite of recent progress made, for example, on the occasional presence of a thermal component in the spectrum along with the ubiquitous non-thermal…

High Energy Astrophysical Phenomena · Physics 2016-03-23 S. Dichiara , C. Guidorzi , L. Amati , F. Frontera , R. Margutti

The physical origin of the >0.1 GeV emission detected from Gamma-Ray Bursts (GRBs) by the Fermi satellite has not yet been completely understood. In this work we consider the GeV light curves of ten GRBs with measured redshift detected by…

High Energy Astrophysical Phenomena · Physics 2015-06-22 L. Nava , G. Vianello , N. Omodei , G. Ghisellini , G. Ghirlanda , A. Celotti , F. Longo , R. Desiante , R. Barniol Duran

Many models of cosmological gamma-ray bursts involve the sudden release of $\sim 10^{51}$ erg which produce shells which expand at relativistic speeds (Lorentz $\Gamma$ factors of $10^{2-3}$). We investigate the kinematic limits on the…

Astrophysics · Physics 2008-11-26 E. E. Fenimore , Claudine Madras , Sergei Nayakshin

We use a simple two-layer outer gap model, whose accelerator consists of a primary region and a screening region, to discuss $\gamma$-ray spectrum of mature pulsars detected by $Fermi$. By solving the Poisson equation with an assumed simple…

High Energy Astrophysical Phenomena · Physics 2015-05-19 Y. Wang , J. Takata , K. S. Cheng

The recent launches of the Einstein Probe (EP) and the Space Variable Objects Monitor (SVOM) mission have led to the detection of a growing number of long GRBs with significant, early soft X-ray flux during their gamma-ray emission,…

High Energy Astrophysical Phenomena · Physics 2025-10-21 Ziming Wang , Chenyu Wang , He Gao , Hua Feng , An Li , Lin Lin , Songyu Shen

Long and short gamma-ray bursts are traditionally associated with galactic environments, where circumburst densities are small or moderate (few to hundreds of protons per cubic cm). However, both are also expected to occur in the disks of…

High Energy Astrophysical Phenomena · Physics 2022-10-26 Davide Lazzati , Gustavo Soares , Rosalba Perna

The average peak-aligned profile of all bursts detected by BATSE with sufficient data quality has a simple ``stretched'' exponential shape, F ~ exp[-(t/t_0)^{1/3}], where $t$ is the time measured from the time for the peak flux of the…

Astrophysics · Physics 2007-05-23 Boris Stern , Roland Svensson , Juri Poutanen

The powerlaw X-ray spectra of active galactic nuclei at moderate to high accretion rates normally appear softer when they brighten, for which the underlying mechanisms are yet unclear. Utilizing XMM-Newton observations and excluding photons…

High Energy Astrophysical Phenomena · Physics 2020-10-29 Yun-Jing Wu , Jun-Xian Wang , Zhen-Yi Cai , Jia-Lai Kang , Teng Liu , Zheng Cai