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In the framework of the internal shock scenario, we model the broadband prompt emission of gamma-ray bursts (GRBs) with emphasis on the GeV-TeV bands, utilizing Monte Carlo simulations that include various processes associated with…

Astrophysics · Physics 2009-06-23 Katsuaki Asano , Susumu Inoue

We study the properties of plasmas containing a low energy thermal photon component at comoving temperature \theta \equiv kT'/m_e c^2 \sim 10^{-5} - 10^{-2} interacting with an energetic electron component, characteristic of, e.g., the…

Astrophysics · Physics 2009-11-11 Asaf Pe'er , Peter Mészáros , Martin J. Rees

The emission mechanism during the prompt phase in gamma-ray bursts (GRBs) can be investigated through correlations between spectral properties. Here, we revisit the correlation relating the instantaneous flux, $F$, and the photon index…

High Energy Astrophysical Phenomena · Physics 2019-01-16 Felix Ryde , Hoi-Fung Yu , Hüsne Dereli-Bégué , Christoffer Lundman , Asaf Pe'er , Liang Li

We investigate a scenario of photons scattering by electrons within a relativistic outflow. The outflow is composed of discrete shells with different speeds. One shell emits radiation for a short duration. Some of this radiation is…

Astrophysics · Physics 2014-03-11 R. -F. Shen , R. Barniol Duran , P. Kumar

We test the models of synchrotron emission presented in Part I of this series (Lloyd & Petrosian, these proceedings) against the distributions and evolution of GRB spectral parameters (particularly the low energy index, $\alpha$). With…

Astrophysics · Physics 2018-11-06 Nicole M. Lloyd-Ronning , Vahe' Petrosian , Robert D. Preece

The low energy spectral slopes of the prompt emission of most gamma-ray bursts (GRBs) are difficult to reconcile with radiatively efficient optically thin emission models irrespective of the radiation mechanism. An alternative is to ascribe…

High Energy Astrophysical Phenomena · Physics 2015-06-11 Indrek Vurm , Yuri Lyubarsky , Tsvi Piran

In this work we numerically calculate the thermal radiation efficiency of the baryonic outflow. The possible outflow acceleration in the transparent stage, which lowers thermal radiation efficiency, has been taken into account. In the…

Cosmology and Nongalactic Astrophysics · Physics 2011-04-07 Yi-Zhong Fan

In most astrophysical processes involving synchrotron radiation, the pitch-angle distribution of the electrons is assumed to be isotropic. However, if electrons are accelerated anisotropically, e.g, in a relativistic shock wave with an…

High Energy Astrophysical Phenomena · Physics 2018-09-05 Yuan-Pei Yang , Bing Zhang

We aim to obtain a measure of the curvature of time-resolved spectra that can be compared directly to theory. This tests the ability of models such as synchrotron emission to explain the peaks or breaks of GBM prompt emission spectra. We…

Gamma-ray bursts are the most energetic electromagnetic sources in the Universe. Their prompt gamma-ray radiation corresponds to an energy release of 1E42-1E47J. Fifty years after their discovery and several dedicated space-based…

High Energy Astrophysical Phenomena · Physics 2019-10-22 J. Michael Burgess , Damien Bégué , Ana Bacelj , Dimitrios Giannios , Francesco Berlato , Jochen Greiner

A plasma instability theory is presented for the prompt radiation from gamma-ray bursts. In the theory, a highly relativistic shell interacts with the interstellar medium through the filamentation and the two-stream instabilities to convert…

Astrophysics · Physics 2009-10-31 J. J. Brainerd

The spectral shape of the prompt emissions of gamma-ray bursts (GRBs) is typically expressed by the Band function: smooth joining of two power-law functions for high-energy and low-energy regions. To reveal the origin of the Band function,…

High Energy Astrophysical Phenomena · Physics 2015-10-21 Katsuaki Asano , Toshio Terasawa

Prompt emission from the very fluent and nearby (z=0.34) gamma-ray burst GRB 130427A was detected by several orbiting telescopes and by ground-based, wide-field-of-view optical transient monitors. Apart from the intensity and proximity of…

Gamma Ray Burst prompt emission is believed to originate from electrons accelerated in a highly relativistic outflow. "Internal shocks" due to collisions between shells ejected by the central engine is a leading candidate for electron…

High Energy Astrophysical Phenomena · Physics 2015-06-05 L. Resmi , B. Zhang

The prompt emission of the gamma-ray bursts is found to be very energetic, releasing ~10^51 ergs in a flash. However, their emission mechanism remains unclear and understanding their spectra is a key to determining the emission mechanism.…

Astrophysics · Physics 2015-06-24 Y. Kaneko , R. D. Preece , M. M. Gonzalez , B. L. Dingus , M. S. Briggs

Although the observed spectra for gamma-ray burst (GRB) prompt emission is well constrained, the underlying radiation mechanism is still not very well understood. We explore photospheric emission in GRB jets by modelling the Comptonization…

High Energy Astrophysical Phenomena · Physics 2021-10-29 Mukul Bhattacharya , Pawan Kumar

One of the principal results obtained by the EGRET experiment aboard the Compton Gamma-Ray Observatory (CGRO) was the detection of several Gamma-ray bursts (GRBs) above 100 MeV. The broad-band spectra obtained for these bursts gave no…

Astrophysics · Physics 2009-10-31 Matthew G. Baring

A small fraction of GRBs with available data down to soft X-rays ($\sim0.5$ keV) have been shown to feature a spectral break in the low-energy part ($\sim1-10$ keV) of their prompt emission spectrum. The overall spectral shape is consistent…

High Energy Astrophysical Phenomena · Physics 2021-05-12 Ioulia Florou , Maria Petropoulou , Apostolos Mastichiadis

We examine the applicability of the stochastic electron acceleration to two high synchrotron peaked blazars, Mrk 421 and Mrk 501, assuming synchrotron self-Compton emission of gamma-rays. Our model considers an emitting region moving at…

High Energy Astrophysical Phenomena · Physics 2015-06-23 Jun Kakuwa , Kenji Toma , Katsuaki Asano , Masaaki Kusunose , Fumio Takahara

Modeling subphotospheric shocks in a gamma-ray burst (GRB) is challenging due to the various timescales that must be resolved, and the fact that the same radiation dynamically mediates the shocks while forming the observed signal. Here, we…

High Energy Astrophysical Phenomena · Physics 2026-04-10 Jona Nordin Nobuoka , Filip Alamaa , Felix Ryde , Christoffer Lundman
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