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Related papers: The GROND GRB sample: II. Fireball parameters for …

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Early optical afterglows have been observed from GRB 990123, GRB 021004, and GRB 021211, which reveal rich emission features attributed to reverse shocks. It is expected that Swift will discover many more early afterglows. Here we…

Astrophysics · Physics 2011-06-21 Bing Zhang , Shiho Kobayashi , Peter Meszaros

Gamma-Ray Bursts (GRBs) afterglows are rapidly decaying signals that pose significant detection challenges, requiring improved methods to track their temporal evolution. In this study, we systematically compare various techniques for…

High Energy Astrophysical Phenomena · Physics 2025-09-23 Léo Le Moigne , Mathieu de Bony de Lavergne , Armand Fiasson , Edna Ruiz-Velasco , David Sanchez , Kenta Terauchi

We present LOFAR imaging observations from the April/May 2020 active episode of magnetar SGR 1935+2154. We place the earliest radio limits on persistent emission following the low-luminosity fast radio burst FRB 200428 from the magnetar. We…

High Energy Astrophysical Phenomena · Physics 2022-11-17 A. J. Cooper , A. Rowlinson , R. A. M. J. Wijers , C. Bassa , K. Gourdji , J. Hessels , A. J. van der Horst , V. Kondratiev , Z. Pleunis , T. Shimwell , S. ter Veen

The behaviour of the afterglow (AG) of gamma-ray bursts (GRBs) directly provides, in the cannonball (CB) model, information about the environment of their progenitor stars. The well observed early temporal decline of the AG of GRB 021211 is…

Astrophysics · Physics 2009-11-07 Shlomo Dado , Arnon Dar , Alvaro De Rujula

Gamma-ray bursts (GRBs) are generally believed to occur in environments where the surrounding medium is either a uniform interstellar medium (ISM) or, in some cases, a dense stellar wind from a massive progenitor. Recently, GRB 191019A has…

High Energy Astrophysical Phenomena · Physics 2025-12-10 Xiao-Hong Zhao

X-ray flashes (XRFs) and X-ray rich gamma-ray bursts (XRGRBs) share many observational characteristics with long duration GRBs, but the reason for which their prompt emission peaks at lower photon energies, $E_p$, is still under debate.…

Astrophysics · Physics 2009-11-10 Jonathan Granot , Enrico Ramirez-Ruiz , Rosalba Perna

When a massive star explodes as a Gamma Ray Burst information about this explosion is retained in the properties of the prompt and afterglow emission. We report on new relationships between the prompt and X-ray afterglow emission of…

High Energy Astrophysical Phenomena · Physics 2015-06-15 Dirk Grupe , John A. Nousek , Peter Veres , Binbin Zhang , Neil Gehrels

A growing number of gamma-ray burst (GRB) afterglows is observed at very-high energies (VHE, $\gtrsim 100$ GeV). Yet, our understanding of the mechanism powering the VHE emission remains baffling. We make use of multi-wavelength…

High Energy Astrophysical Phenomena · Physics 2023-05-25 Ersilia Guarini , Irene Tamborra , Damien Bégué , Annika Rudolph

Gamma-ray bursts (GRBs) are cosmic events occurring at large distances beyond our galaxy. They provide a unique opportunity to study electromagnetic patterns not seen elsewhere. When the collimated GRB outflow interacts with the outer…

Based on the early-year observations from Neil Gehrels \emph{Swift} Observatory, \cite{liang07} performed a systematic analysis for the shallow decay component of gamma-ray bursts (GRBs) X-ray afterglow, in order to explore its physical…

High Energy Astrophysical Phenomena · Physics 2019-10-02 Litao Zhao , Binbin Zhang , He Gao , Lin Lan , Houjun Lü , Bing Zhang

The exceptionally high luminosities of gamma-ray bursts (GRBs), gradually emerging as extremely useful probes of star formation, make them promising tools for exploration of the high-redshift Universe. Here we present a carefully selected…

The energy requirements of gamma ray bursts have in past been poorly constrained because of three major uncertainties: The distances to bursts, the degree of burst beaming, and the efficiency of gamma ray production. The first of these has…

Astrophysics · Physics 2008-11-26 James E. Rhoads

The postburst object of a GRB is likely to be a highly magnetized, rapidly rotating compact object (e.g., a millisecond magnetar), which could produce an ultrarelativistic electron-positron-pair wind. The interaction of such a wind with an…

Astrophysics · Physics 2009-11-16 Yun-Wei Yu , Zi-Gao Dai

The two leading contenders for the theory of gamma-ray bursts (GRBs) and their afterglows, the Fireball and Cannonball models, are compared and their predictions are confronted, within space limitations, with key GRB observations, including…

Astrophysics · Physics 2009-11-13 Arnon Dar

The Swift X-ray Telescope (XRT) has discovered that flares are quite common in early X-ray afterglows of Gamma-Ray Bursts (GRBs), being observed in roughly 50% of afterglows with prompt followup observations. The flares range in fluence…

We present numerical simulations of Gamma-Ray Bursts arising from external shocks in the impulsive and wind models, including a weak or a strong coupling between electrons and protons plus magnetic fields, and analyze the burst features in…

Astrophysics · Physics 2009-10-30 A. Panaitescu , P. Meszaros

Short-duration GRBs with extended emission form a subclass of short GRBs, comprising about 15% of the short-duration sample. Afterglow detections of short GRBs are also rare (about 30%) due to their smaller luminosity. We present a…

We continue our systematic statistical study on optical afterglow data of gamma-ray bursts (GRBs). We present the apparent magnitude distributions of early optical afterglows at different epochs (t= 10^2 s, t = 10^3 s, and 1 hour) for the…

High Energy Astrophysical Phenomena · Physics 2015-06-16 Xiang-Gao Wang , En-Wei Liang , Liang Li , Rui-Jing Lu , Jian-Yan Wei , Bing Zhang

We present a comprehensive compilation of short-duration gamma-ray burst (GRB) afterglows in the X-ray, optical, and radio bands, comprising 150 events discovered primarily by the Neil Gehrels Swift Observatory over 2005-2023. We pair these…

High Energy Astrophysical Phenomena · Physics 2025-08-29 Cristian Castrejon , Anya E. Nugent , Wen-fai Fong , Genevieve Schroeder , Alicia Rouco Escorial , Olivia Guerra

We present science highlights and performance from the Swift X-ray Telescope (XRT), which was launched on November 20, 2004. The XRT covers the 0.2-10 keV band, and spends most of its time observing gamma-ray burst (GRB)afterglows, though…

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