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Achromatic breaks in afterglow light curves of gamma-ray bursts (GRBs) arise naturally if the product of the jet's Lorentz factor \gamma and opening angle \Theta_j satisfies (\gamma \Theta_j) >> 1 at the onset of the afterglow phase, i.e.,…

High Energy Astrophysical Phenomena · Physics 2011-03-28 Alexander Tchekhovskoy , Ramesh Narayan , Jonathan C. McKinney

We compute the kinematical dependence of the peak luminosity, the pulse width and the spectral lag of the peak luminosity on the viewing angle $\theta_v$ of a jet. For appropriate model parameters we obtain the peak luminosity-spectral lag…

Astrophysics · Physics 2009-11-06 Kunihito Ioka , Takashi Nakamura

We report observations of the early light curves of GRB 060418 and GRB 060607A, carried out with the pink robotic telescope REM. A clear peak is detected for both events, which is interpreted as the onset of the afterglow, that is the time…

Astrophysics · Physics 2019-08-14 Daniele Malesani , Emilio Molinari , Susanna Vergani , Stefano Covino

Relativistic outflows in the form of jets are common in many astrophysical objects. By their very nature, jets have angle dependent velocity profiles, Gamma = Gamma(r, theta, phi), where Gamma is the outflow Lorentz factor. In this work we…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Christoffer Lundman , Asaf Pe'er , Felix Ryde

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

We suggest a connection between the pulse paradigm at gamma-ray energies and the recently demonstrated luminosity distribution in gamma-ray bursts: the spectral evolution timescale of pulse structures is anticorrelated with peak luminosity,…

Astrophysics · Physics 2009-10-31 J. P. Norris , G. F. Marani , J. T. Bonnell

Gamma ray bursts (GRBs) have great advantages for their huge burst energies, luminosities and high redshifts in probing the Universe. A few interesting luminosity correlations of GRBs have been used to test cosmology models. Especially, for…

High Energy Astrophysical Phenomena · Physics 2015-05-27 M. Xu , Y. F. Huang

GRB 170817A/GW 170817 is the first GRB clearly viewed far from the GRB jet's symmetry axis. Its afterglow was densely monitored over a wide range of frequencies and times. It has been modeled extensively, primarily numerically, and although…

High Energy Astrophysical Phenomena · Physics 2020-03-06 Paz Beniamini , Jonathan Granot , Ramandeep Gill

Recent detections of gamma-ray bursts (GRBs) at TeV energies opened new prospects for investigating radiative environments and particle acceleration mechanisms under extreme conditions. In this paper, we study the afterglows of these GRBs -…

High Energy Astrophysical Phenomena · Physics 2025-11-27 L. Foffano , M. Tavani

Compact binary mergers, with neutron stars or neutron star and black-hole components, are thought to produce various electromagnetic counterparts: short gamma-ray bursts (GRBs) from ultra-relativistic jets followed by broadband afterglow;…

High Energy Astrophysical Phenomena · Physics 2017-06-28 Gavin P Lamb , Shiho Kobayashi

We determine the basic physical characteristics of eight Gamma-Ray Bursts -- 980519, 990123, 990510, 991028, 991216, 000301c, 000926 and 010222 -- by modelling the broadband emission of their afterglows. We find that the burst kinetic…

Astrophysics · Physics 2009-11-07 A. Panaitescu , P. Kumar

Early multiwavelength observations offer crucial insights into the nature of the relativistic jets responsible for gamma-ray bursts and their interaction with the surrounding medium.We present data of GRB 240825A from 17 space- and…

Evidence suggests that the gamma-ray burst (GRB) ejecta is likely magnetized, although the degree of magnetization of the ejecta is unknown. We derive a rigorous analytical solution for the relativistic 90 degree shocks under the ideal MHD…

Astrophysics · Physics 2009-11-10 Bing Zhang , Shiho Kobayashi

GRB 160625B is an extremely-bright outburst with well-monitored afterglow emission. The geometry-corrected energy is high up to $\sim 5.2\times10^{52}$ erg or even $\sim 8\times 10^{52}$ erg, rendering it the most energetic GRB prompt…

High Energy Astrophysical Phenomena · Physics 2017-02-15 Yuan-Zhu Wang , Hao Wang , Shuai Zhang , Yun-Feng Liang , Zhi-Ping Jin , Hao-Ning He , Neng-Hui Liao , Yi-Zhong Fan , Da-Ming Wei

We report on the multiwavelength observations of the bright, long gamma-ray burst \GRB, by the \Fermi and \Swift observatories, and by the MOA and GROND optical telescopes. The analysis of the prompt phase reveals that \GRB shares many…

High Energy Astrophysical Phenomena · Physics 2013-01-11 LAT Collaboration , GBM Collaboration , Swift Collaboration , GROND Collaboration , the MOA Collaboration

GRB 201015A is a peculiarly low luminosity, spectrally soft gamma-ray burst (GRB), with $T_{\rm 90} = 9.8 \pm 3.5$ s (time interval of detection of 90\% of photons from the GRB), and an associated supernova (likely to be type Ic or Ic-BL).…

Observations of very early multi-wavelength afterglows are critical to reveal the properties of the radiating fireball and its environment as well as the central engine of gamma-ray bursts (GRBs). We report our optical observations of GRB…

Using the resultant profiles from 3D hydrodynamic simulations of relativistic jets interacting with neutron star merger wind ejecta, we show how the inhomogeneity of energy and velocity {across the jet surface profile} can alter the…

High Energy Astrophysical Phenomena · Physics 2022-10-31 Gavin P Lamb , Lorenzo Nativi , Stephan Rosswog , D. Alexander Kann , Andrew Levan , Christoffer Lundman , Nial Tanvir

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

HETE-II and BeppoSAX have produced a sample of GRBs and XRFs with known redshifts and $E_{pk}$. This sample provides four important empirical constraints on the nature of the source jets: Log $E_{iso}$ is approximately uniformly distributed…

Astrophysics · Physics 2011-04-11 C. Graziani , D. Q. Lamb , T. Q. Donaghy