scholarly journals OBSERVATIONAL PROPERTIES OF TEV DETECTED GRB 180720B, GRB 190114C AND GRB 190829A

2021 ◽  
Vol 53 ◽  
pp. 113-123
Author(s):  
R. Gupta ◽  
S. B. Pandey ◽  
A. J. Castro-Tirado ◽  
A. Kumar ◽  
A. Aryan ◽  
...  
Keyword(s):  
Synchrotron Radiation ◽  
Late Time ◽  
Energy Evolution ◽  
Radiation Mechanisms ◽  
Radiation Mechanism ◽  
Peak Energy ◽  
Inverse Compton ◽  
Γ Ray ◽  
Prompt Emission

TeV emissions from γ-ray bursts are very important to study their origin and the radiation mechanisms in detail. Recent observations of TeV photons in some of the GRBs are challenging to be explained by the traditional Synchrotron radiation mechanism. In this work, we present the results of a detailed investigation of the prompt and afterglow emissions of recently discovered TeV GRBs (GRB 180720B, GRB 190114C, and GRB 190829A) based on the publicly available prompt and afterglow data including 10.4m GTC and 1.3m DFOT telescopes observations of the first HESS and MAGIC bursts, respectively. Timeresolved spectroscopy of prompt emission of GRB 180720B and GRB 190114C shows an intensity tracking nature of peak energy. In the case of GRB 190829A, peak energy evolution shows a hard to soft tracking trend followed by a very soft and chaotic trend. GRB 190829A is a peculiar intermediate luminous two episodic burst with first emission episode outlier to Amati correlation. We analyzed the late time Fermi-LAT emission that encapsulates the H.E.S.S. and MAGIC observations. Some of the LAT photons are likely to be associated with these GRBs and they could have an Inverse Compton radiation mechanism.

Possible physical explanation of the intrinsic Ep,i-“intensity” correlation commonly used to “standardize” GRBs

2016 ◽  
Vol 25 (05) ◽  
pp. 1630014 ◽  
Author(s):  
Filippo Frontera ◽  
Lorenzo Amati ◽  
Ruben Farinelli ◽  
Simone Dichiara ◽  
Cristiano Guidorzi ◽  
...  
Keyword(s):  
Thermal Bath ◽  
Time Resolved ◽  
Peak Energy ◽  
Inverse Compton ◽  
Energy Formula ◽  
Two Phases ◽  
Photospheric Model ◽  
Photospheric Radius ◽  
Prompt Emission ◽  
Broad Energy

It is recognized that very likely the correlation between peak energy [Formula: see text] and bolometric intensity is intrinsic to GRBs. However, its physical origin is still debated. In this paper, we will discuss a possible interpretation of the correlation in the light of a GRB prompt emission spectral model, grbcomp, proposed in [L. Titarchuk, R. Farinelli, F. Frontera and L. Amati, Astrophys. J. 752 (2012) 116]. grbcomp is essentially a photospheric model for the prompt emission of GRBs. Its main ingredients are a thermal bath of soft seed photons and a subrelativistically expanding outflow plasma, consequence of the star explosion. The emerging spectrum is the result of two phases: first, up to the photospheric radius, Comptonization of a subrelativistic electron outflow with thermal bath of soft photons, then, convolution of the Comptonized photons in the first phase with a Green function. The result of this convolution is consistent with different physical processes, in particular Inverse Compton. grbcomp has been successfully tested using a significant sample of GRB time resolved spectra in the broad energy band from 2[Formula: see text]keV to 2[Formula: see text]MeV [F. Frontera, L. Amati, R. Farinelli, S. Dichiara, C. Guidorzi, R. Landi and L. Titarchuk, Astrophys. J. 779 (2013) 175].

scholarly journals On the Reclassification of Short GRBs

2012 ◽  
Vol 8 (S290) ◽  
pp. 361-363
Author(s):  
Zhibin Zhang ◽  
Yongfeng Huang ◽  
Hongchao Liu
Keyword(s):  
Gamma Ray ◽  
Gamma Ray Bursts ◽  
Radiation Mechanism ◽  
Duration Time ◽  
Central Engine ◽  
Peak Energy ◽  
Thermal Origin ◽  
Γ Ray ◽  
Short Grbs ◽  
Extended Emission

AbstractBy collecting 17 short gamma-ray bursts with necessary data, we find a correlation of Lp ∝ Ep,i1.7, which is very consistent with that derived from a greatly expanded sample of 148 Swift long gamma-ray bursts. It is argued that the radiation mechanism of both long and short gamma-ray bursts should be similar, i.e., of quasi-thermal origin caused by the photosphere and the dissipation occurring very near the central engine. In addition, we suggest that the Ep,i-Lp relation can be used to identified a burst among normal short bursts, short bursts with extended emission and long bursts with short-hard properties. We also find the ratio of peak energy to fluence in the prompt γ-ray band is a prospective discriminator, similar to the traditional duration time.

scholarly journals GRB Polarization: A Unique Probe of GRB Physics

Galaxies ◽  
2021 ◽  
Vol 9 (4) ◽  
pp. 82
Author(s):  
Ramandeep Gill ◽  
Merlin Kole ◽  
Jonathan Granot
Keyword(s):  
Gamma Ray ◽  
High Sensitivity ◽  
Theoretical Models ◽  
Current Status ◽  
Radiation Mechanisms ◽  
Reverse Shock ◽  
Radiation Mechanism ◽  
Time Resolved ◽  
Polarization Measurements ◽  
Prompt Emission

Over half a century from the discovery of gamma-ray bursts (GRBs), the dominant radiation mechanism responsible for their bright and highly variable prompt emission remains poorly understood. Spectral information alone has proven insufficient for understanding the composition and main energy dissipation mechanism in GRB jets. High-sensitivity polarimetric observations from upcoming instruments in this decade may help answer such key questions in GRB physics. This article reviews the current status of prompt GRB polarization measurements and provides comprehensive predictions from theoretical models. A concise overview of the fundamental questions in prompt GRB physics is provided. Important developments in gamma-ray polarimetry including a critical overview of different past instruments are presented. Theoretical predictions for different radiation mechanisms and jet structures are confronted with time-integrated and time-resolved measurements. The current status and capabilities of upcoming instruments regarding the prompt emission are presented. The very complimentary information that can be obtained from polarimetry of X-ray flares as well as reverse-shock and early to late forward-shock (afterglow) emissions are highlighted. Finally, promising directions for overcoming the inherent difficulties in obtaining statistically significant prompt-GRB polarization measurements are discussed, along with prospects for improvements in the theoretical modeling, which may lead to significant advances in the field.

scholarly journals A full polar cap cascade model: pulsar γ-ray and X-ray luminosities

2000 ◽  
Vol 177 ◽  
pp. 481-482
Author(s):  
Bing Zhang ◽  
Alice K. Harding
Keyword(s):  
Synchrotron Radiation ◽  
Cascade Model ◽  
Polar Cap ◽  
X Ray ◽  
Inverse Compton ◽  
Primary Particles ◽  
Γ Ray

AbstractWe propose a full polar cap cascade model which includes the curvature and inverse Compton emission of the primary particles, and both synchrotron radiation and inverse Compton of the higher generation pairs. Such a full cascade model can reproduce both theLγ∝ (Lsd)1/2and theLx~ 10−3Lsddependences observed from the known spin-powered pulsars.

Inverse Compton γ-ray source for nuclear physics and related applications

1996 ◽  
Vol 375 (1-3) ◽  
pp. 530-534 ◽  
Author(s):  
P.G O'Shea ◽  
V.N Litvinenko ◽  
J.M.J Madey ◽  
N.R Roberson ◽  
E.C Schreiber ◽  
...  
Keyword(s):  
Nuclear Physics ◽  
Inverse Compton ◽  
Γ Ray

scholarly journals The Origin of Continuum Emission in Active Galactic Nuclei

1994 ◽  
Vol 159 ◽  
pp. 5-16 ◽  
Author(s):  
Joel N. Bregman
Keyword(s):  
Accretion Disk ◽  
Near Infrared ◽  
Galactic Nuclei ◽  
Black Body ◽  
Continuum Emission ◽  
Radiation Mechanism ◽  
X Ray ◽  
Pair Plasma ◽  
Inverse Compton ◽  
The Continuum

The general understanding of the continuum emission from AGN has changed from the picture where nonthermal processes were responsible for all of the emission. The current body of observation indicates that there are two types of objects, one being the blazar class (or blazar component), where nearly all of the emission is nonthermal, due primarily to synchrotron and inverse Compton emission. Variability studies indicate that the emitting region decreases with size from the radio through the X-ray region, where the size of the X-ray region is of order a light hour. More than two dozen of these radio-loud AGNs have been detected at GeV energies (one source at TeV energies), for which the radiation mechanism may be inverse Compton mechanism.In the other class, the radio-quiet AGN (component), the emission is almost entirely thermal, with radiation from dust dominating the near infrared to submillimeter region. The optical to soft X-ray emission is often ascribed to black body emission from an opaque accretion disk, but variability studies may not be consistent with expectations. Another attractive model has free-free emission being responsible for the optical to soft X-ray emission. The highest frequencies at which these AGN are detected is the MeV range, and these data should help to determine if this emission is produced in a scattering atmosphere, such as that around an accretion disk, or by another model involving an opaque pair plasma.

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