scholarly journals Delayed MeV–GeV Gamma-Ray Photons in Gamma-Ray Bursts: An Effect of Electromagnetic Cascades of Very High Energy Gamma Rays in the Infrared/Microwave Background

1996 ◽  
Vol 459 (2) ◽  
Author(s):  
L. X. Cheng ◽  
K. S. Cheng
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Microwave Background ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

Very high-energy gamma rays from gamma-ray bursts

2007 ◽  
Vol 365 (1854) ◽  
pp. 1343-1356 ◽  
Author(s):  
Paula M Chadwick
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Gamma Ray Burst ◽  
Gamma Ray Astronomy ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

Very high-energy (VHE) gamma-ray astronomy has undergone a transformation in the last few years, with telescopes of unprecedented sensitivity having greatly expanded the source catalogue. Such progress makes the detection of a gamma-ray burst at the highest energies much more likely than previously. This paper describes the facilities currently operating and their chances for detecting gamma-ray bursts, and reviews predictions for VHE gamma-ray emission from gamma-ray bursts. Results to date are summarized.

scholarly journals Very High Energy Gamma Rays from Plerions: CANGAROO Results

1998 ◽  
Vol 188 ◽  
pp. 125-128
Author(s):  
T. Kifune
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
High Energy ◽  
Current Status ◽  
Emission Region ◽  
Thermal Processes ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

The current status of very high energy gamma ray astronomy (in ~ 1 TeV region) is described by using as example results of CANGAROO (Collaboration of Australia and Nippon for a GAmma Ray Observatory in the Outback). Gamma rays at TeV energies, emitted through inverse Compton effect of electrons or π0 decay from proton interaction, provide direct evidence on “hot” non-thermal processes of the Universe, as well as environmental features, such as the strength of magnetic field in the emission region, for the non-thermal processes.

scholarly journals Searching for very-high-energy gamma-ray bursts from evaporating primordial black holes

2008 ◽  
Vol 34 (8) ◽  
pp. 509-514 ◽  
Author(s):  
V. B. Petkov ◽  
E. V. Bugaev ◽  
P. A. Klimai ◽  
M. V. Andreev ◽  
V. I. Volchenko ◽  
...  
Keyword(s):  
Black Holes ◽  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Primordial Black Holes ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

scholarly journals THE VERY BRIGHT AND NEARBY GRB130427A: THE EXTRA HARD SPECTRAL COMPONENT AND IMPLICATIONS FOR VERY HIGH-ENERGY GAMMA-RAY OBSERVATIONS OF GAMMA-RAY BURSTS

2014 ◽  
Vol 28 ◽  
pp. 1460174
Author(s):  
PAK-HIN THOMAS TAM
Keyword(s):  
Gamma Ray ◽  
Spectral Component ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
Prompt Gamma ◽  
Large Area ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

The extended high-energy gamma-ray (>100 MeV) emission occurring after the prompt gamma-ray bursts (GRBs) is usually characterized by a single power-law spectrum, which has been explained as the afterglow synchrotron radiation. We report on the Fermi Large Area Telescope (LAT) observations of the >100 MeV emission from the very bright and nearby GRB 130427A, up to ~100 GeV. By performing time-resolved spectral fits of GRB 130427A, we found a strong evidence of an extra hard spectral component above a few GeV that exists in the extended high-energy emission of this GRB. This extra spectral component may represent the first clear evidence of the long sought-after afterglow inverse Compton emission. Prospects for observations at the very high-energy gamma-rays, i.e., above 100 GeV, are described.

scholarly journals Very high energy gamma-rays from flat spectrum radio quasars

2014 ◽  
Vol 10 (S313) ◽  
pp. 27-32
Author(s):  
Elina Lindfors
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
High Energy ◽  
High Energy Gamma ◽  
Spectrum Radio ◽  
Very High Energy ◽  
Energy Gamma ◽  
Emission Models ◽  
Γ Rays ◽  
Very High

AbstractThe detection of Flat Spectrum Radio Quasars (FSRQs) in the Very High Energy (VHE, E>100 GeV) range is challenging, mainly because of their steep soft spectra and distance. Nevertheless four FSRQs are now known to be VHE emitters. The detection of the VHE γ-rays has challenged the emission models of these sources. The sources are also found to exhibit very different behavior. I will give an overview of what is known about the VHE emission of these sources and about the multiwavelength signatures that are connected to the VHE gamma-ray emission.

scholarly journals Constraints on Very High Energy Gamma‐Ray Emission from Gamma‐Ray Bursts

2005 ◽  
Vol 630 (2) ◽  
pp. 996-1002 ◽  
Author(s):  
R. Atkins ◽  
W. Benbow ◽  
D. Berley ◽  
E. Blaufuss ◽  
D. G. Coyne ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Bursts ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Gamma Ray Emission ◽  
Very High

scholarly journals H.E.S.S. observations of RX J1713.7−3946 with improved angular and spectral resolution: Evidence for gamma-ray emission extending beyond the X-ray emitting shell

2018 ◽  
Vol 612 ◽  
pp. A6 ◽  
Author(s):  
◽  
H. Abdalla ◽  
A. Abramowski ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Supernova Remnants ◽  
Gamma Ray ◽  
High Energy ◽  
High Energy Gamma ◽  
The Past ◽  
Very High Energy ◽  
Energy Gamma ◽  
Gamma Ray Emission ◽  
Very High

Supernova remnants exhibit shock fronts (shells) that can accelerate charged particles up to very high energies. In the past decade, measurements of a handful of shell-type supernova remnants in very high-energy gamma rays have provided unique insights into the acceleration process. Among those objects, RX J1713.7−3946 (also known as G347.3−0.5) has the largest surface brightness, allowing us in the past to perform the most comprehensive study of morphology and spatially resolved spectra of any such very high-energy gamma-ray source. Here we present extensive new H.E.S.S. measurements of RX J1713.7−3946, almost doubling the observation time compared to our previous publication. Combined with new improved analysis tools, the previous sensitivity is more than doubled. The H.E.S.S. angular resolution of 0.048° (0.036° above 2 TeV) is unprecedented in gamma-ray astronomy and probes physical scales of 0.8 (0.6) parsec at the remnant’s location. The new H.E.S.S. image of RX J1713.7−3946 allows us to reveal clear morphological differences between X-rays and gamma rays. In particular, for the outer edge of the brightest shell region, we find the first ever indication for particles in the process of leaving the acceleration shock region. By studying the broadband energy spectrum, we furthermore extract properties of the parent particle populations, providing new input to the discussion of the leptonic or hadronic nature of the gamma-ray emission mechanism.

The CANGAROO Project: Very High Energy Gamma-ray Astronomy at Woomera

1992 ◽  
Vol 10 (1) ◽  
pp. 27-29 ◽  
Author(s):  
P.G. Edwards ◽  
A.G. Gregory ◽  
J.R. Patterson ◽  
M.D. Roberts ◽  
G.P. Rowell ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
High Energy ◽  
Gamma Ray Astronomy ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
The University ◽  
Very High ◽  
Atmospheric Čerenkov Technique

AbstractIn this paper the Very High Energy (VHE) gamma-ray astronomy program at the University of Adelaide is described. VHE gamma rays with energies above ~5 × 1011eV are observed using the atmospheric Cerenkov technique. Results from the first three years observations at Woomera and the current upgrading of the telecope are described. The CANGAROO project, a collaboration between the University of Adelaide and a number of Japanese institutions, is also introduced.

scholarly journals Multifrequency Behaviour of the Gamma-Ray Binary System PSR B1259-63: Modelling the FERMI Flare

2014 ◽  
Vol 1 (1) ◽  
pp. 127-131
Author(s):  
Brian Van Soelen ◽  
Pieter J. Meintjes
Keyword(s):  
Binary System ◽  
Gamma Rays ◽  
Gamma Ray ◽  
High Energy ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Initial Results ◽  
Very High

This paper presents a brief overview of the multifrequency properties of the gamma-ray binary system PSR B1259-63 from radio to very high energy gamma-rays. A summary is also presented of the various models put forward to explain the Fermi "flare" detected in 2011. Initial results are presented of a new turbulence driven model to explain the GeV observations.

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