scholarly journals The capture of main sequence stars and giant stars by a massive black hole

2006 ◽  
Vol 2 (S238) ◽  
pp. 403-404
Author(s):  
Y. Lu ◽  
Y. F Huang ◽  
Z. Zheng ◽  
S. N. Zhang
Keyword(s):  
Black Hole ◽  
Gamma Rays ◽  
Main Sequence ◽  
Gamma Ray ◽  
High Energy ◽  
Main Sequence Stars ◽  
Massive Black Hole ◽  
Giant Stars ◽  
Very High Energy ◽  
Very High

AbstractSince the mass-radius relation is quite different for a main sequence (MS) star and a giant (G) star, we find that the radiation efficiencies in the star capture processes by a black hole (BH) are also very different. This may provide a useful way to distinguish the capture of MS and G stars. Comparing with observations of the very high energy (VHE) gamma-ray emissions, we argue the event that triggers the gamma-ray emission in the energy range 4–40 TeV should be a G star capture. On the other hand, the capture of MS stars by the massive BH is required when the measured spectrum of VHE gamma-rays extends from 109 to 1015 eV.

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 Very High Energy Gamma-Ray Radiation from the Stellar Mass Black Hole Binary Cygnus X-1

2007 ◽  
Vol 665 (1) ◽  
pp. L51-L54 ◽  
Author(s):  
J. Albert ◽  
E. Aliu ◽  
H. Anderhub ◽  
P. Antoranz ◽  
A. Armada ◽  
...  
Keyword(s):  
Black Hole ◽  
Gamma Ray ◽  
High Energy ◽  
Stellar Mass ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Black Hole Binary ◽  
Very High

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 Revealing x-ray and gamma ray temporal and spectral similarities in the GRB 190829A afterglow

Science ◽  
2021 ◽  
Vol 372 (6546) ◽  
pp. 1081-1085
Author(s):  
◽  
H. Abdalla ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
E. O. Angüner ◽  
...  
Keyword(s):  
Gamma Rays ◽  
Gamma Ray ◽  
High Energy ◽  
X Ray ◽  
Photon Index ◽  
Very High Energy ◽  
Stereoscopic System ◽  
Very High ◽  
Intrinsic Energy

Gamma-ray bursts (GRBs), which are bright flashes of gamma rays from extragalactic sources followed by fading afterglow emission, are associated with stellar core collapse events. We report the detection of very-high-energy (VHE) gamma rays from the afterglow of GRB 190829A, between 4 and 56 hours after the trigger, using the High Energy Stereoscopic System (H.E.S.S.). The low luminosity and redshift of GRB 190829A reduce both internal and external absorption, allowing determination of its intrinsic energy spectrum. Between energies of 0.18 and 3.3 tera–electron volts, this spectrum is described by a power law with photon index of 2.07 ± 0.09, similar to the x-ray spectrum. The x-ray and VHE gamma-ray light curves also show similar decay profiles. These similar characteristics in the x-ray and gamma-ray bands challenge GRB afterglow emission scenarios.

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 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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