Very high energy astrophysics with the SHALON Cherenkov telescopes

2020 ◽  
Vol 952 ◽  
pp. 161775 ◽  
Author(s):  
V.G. Sinitsyna ◽  
V.Y. Sinitsyna ◽  
S.S. Borisov ◽  
A.I. Klimov ◽  
R.M. Mirzafatikhov ◽  
...  
Keyword(s):  
High Energy ◽  
High Energy Astrophysics ◽  
Cherenkov Telescopes ◽  
Very High Energy ◽  
Very High

scholarly journals The Making of Catalogues of Very-High-Energy γ-ray Sources

Universe ◽  
2021 ◽  
Vol 7 (11) ◽  
pp. 421
Author(s):  
Mathieu de Naurois
Keyword(s):  
Galactic Plane ◽  
Population Studies ◽  
High Energy ◽  
Cherenkov Telescopes ◽  
Background Rejection ◽  
Fine Grained ◽  
Very High Energy ◽  
Advanced Analysis ◽  
Γ Ray ◽  
Very High

Thirty years after the discovery of the first very-high-energy γ-ray source by the Whipple telescope, the field experienced a revolution mainly driven by the third generation of imaging atmospheric Cherenkov telescopes (IACTs). The combined use of large mirrors and the invention of the imaging technique at the Whipple telescope, stereoscopic observations, developed by the HEGRA array and the fine-grained camera, pioneered by the CAT telescope, led to a jump by a factor of more than ten in sensitivity. The advent of advanced analysis techniques led to a vast improvement in background rejection, as well as in angular and energy resolutions. Recent instruments already have to deal with a very large amount of data (petabytes), containing a large number of sources often very extended (at least within the Galactic plane) and overlapping each other, and the situation will become even more dramatic with future instruments. The first large catalogues of sources have emerged during the last decade, which required numerous, dedicated observations and developments, but also made the first population studies possible. This paper is an attempt to summarize the evolution of the field towards the building up of the source catalogues, to describe the first population studies already made possible, and to give some perspectives in the context of the upcoming, new generation of instruments.

scholarly journals Gamma-ray emission in radio galaxies, from MeV to TeV

2018 ◽  
Vol 14 (S342) ◽  
pp. 158-166
Author(s):  
Eleonora Torresi
Keyword(s):  
Gamma Ray ◽  
Radio Galaxies ◽  
High Energy ◽  
Cherenkov Telescopes ◽  
New Class ◽  
Very High Energy ◽  
Structure Complexity ◽  
The Impact ◽  
Jet Structure ◽  
Very High

AbstractThanks to the Fermi λ-ray satellite and the current Imaging Atmospheric Cherenkov Telescopes, radio galaxies have arisen as a new class of high- and very-high energy emitters. The favourable orientation of their jets makes radio galaxies extremely relevant in addressing important issues such as: (i) revealing the jet structure complexity; (ii) localising the emitting region(s) of high- and very-high energy radiation; (iii) understanding the physical processes producing these photons. In this review the main results on the λ-ray emission studies of radio galaxies from the MeV to TeV regimes will be presented, and the impact of future Cherenkov Telescope Array observations will be discussed.

scholarly journals THE H.E.S.S. EXTRAGALACTIC SKY

2014 ◽  
Vol 28 ◽  
pp. 1460163
Author(s):  
◽  
JEAN-PHILIPPE LENAIN
Keyword(s):  
Radio Galaxies ◽  
High Energy ◽  
Bl Lac Objects ◽  
Dominant Class ◽  
Cherenkov Telescopes ◽  
Spectrum Radio ◽  
System Experiment ◽  
Very High Energy ◽  
Stereoscopic System ◽  
Very High

More than fifty extragalactic very high energy (VHE; E > 100 GeV) sources have been found using ground-based imaging atmospheric Cherenkov telescopes, about twenty of which have been discovered using the H.E.S.S. (High Energy Stereoscopic System) experiment based in Namibia. Even though BL Lac objects are the dominant class of VHE detected extragalactic objects, other types of sources (starburst galaxies, radio galaxies or flat spectrum radio quasars) begin to emerge. A review of the extragalactic sources studied with H.E.S.S. is given, with an emphasis on new results.

scholarly journals Importance of axion-like particles for very-high-energy astrophysics

2012 ◽  
Vol 375 (5) ◽  
pp. 052029
Author(s):  
Marco Roncadelli ◽  
Alessandro De Angelis ◽  
Giorgio Galanti
Keyword(s):  
High Energy ◽  
High Energy Astrophysics ◽  
Very High Energy ◽  
Very High

scholarly journals A fast muon tagger method for Imaging Atmospheric Cherenkov Telescopes

2020 ◽  
Vol 1548 (1) ◽  
pp. 012036
Author(s):  
L Di Venere ◽  
G Giavitto ◽  
F Giordano ◽  
R López-Coto ◽  
R Pillera
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Silicon Photomultiplier ◽  
Cherenkov Telescopes ◽  
Large Size ◽  
Very High Energy ◽  
Energy Gamma ◽  
Design Options ◽  
Very High ◽  
Computation Speed

Abstract The Cherenkov Telescope Array (CTA) will be the next major observatory for Very High Energy gamma-ray astronomy. Its optical throughput calibration relies on muon Cherenkov rings. This work is aimed at developing a fast and efficient muon tagger at the camera level for the CTA telescopes. A novel technique to tag muons using the capabilities of silicon photomultiplier Compact High-Energy Camera CHEC-S, one of the design options for the camera of the small size telescopes, has been developed, studying and comparing different algorithms such as circle fitting with the Taubin method, machine learning using a neural network and simple pixel counting. Their performance in terms of efficiency and computation speed was investigated using simulations with varying levels of night sky background light. The application of the best performing method to the large size telescope camera has also been studied, to improve the speed of the muon preselection.

scholarly journals Observation of the Gamma-Ray Binary HESS J0632+057 with the H.E.S.S., MAGIC, and VERITAS Telescopes

2021 ◽  
Vol 923 (2) ◽  
pp. 241
Author(s):  
C. B. Adams ◽  
W. Benbow ◽  
A. Brill ◽  
J. H. Buckley ◽  
M. Capasso ◽  
...  
Keyword(s):  
Binary Systems ◽  
Gamma Ray ◽  
High Energy ◽  
Energy Bands ◽  
X Ray ◽  
Cherenkov Telescopes ◽  
Orbital Cycles ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

Abstract The results of gamma-ray observations of the binary system HESS J0632 + 057 collected during 450 hr over 15 yr, between 2004 and 2019, are presented. Data taken with the atmospheric Cherenkov telescopes H.E.S.S., MAGIC, and VERITAS at energies above 350 GeV were used together with observations at X-ray energies obtained with Swift-XRT, Chandra, XMM-Newton, NuSTAR, and Suzaku. Some of these observations were accompanied by measurements of the Hα emission line. A significant detection of the modulation of the very high-energy gamma-ray fluxes with a period of 316.7 ± 4.4 days is reported, consistent with the period of 317.3 ± 0.7 days obtained with a refined analysis of X-ray data. The analysis of data from four orbital cycles with dense observational coverage reveals short-timescale variability, with flux-decay timescales of less than 20 days at very high energies. Flux variations observed over a timescale of several years indicate orbit-to-orbit variability. The analysis confirms the previously reported correlation of X-ray and gamma-ray emission from the system at very high significance, but cannot find any correlation of optical Hα parameters with fluxes at X-ray or gamma-ray energies in simultaneous observations. The key finding is that the emission of HESS J0632 + 057 in the X-ray and gamma-ray energy bands is highly variable on different timescales. The ratio of gamma-ray to X-ray flux shows the equality or even dominance of the gamma-ray energy range. This wealth of new data is interpreted taking into account the insufficient knowledge of the ephemeris of the system, and discussed in the context of results reported on other gamma-ray binary systems.

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