scholarly journals Detection of variable VHE γ-ray emission from the extra-galactic γ-ray binary LMC P3

2018 ◽  
Vol 610 ◽  
pp. L17 ◽  
Author(s):  
◽  
H. Abdalla ◽  
A. Abramowski ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
...  
Keyword(s):  
Binary System ◽  
Orbital Period ◽  
Statistical Significance ◽  
Large Magellanic Cloud ◽  
High Energy ◽  
Data Set ◽  
Very High Energy ◽  
Stereoscopic System ◽  
Γ Ray ◽  
Very High

Context. Recently, the high-energy (HE, 0.1–100 GeV) γ-ray emission from the object LMC P3 in the Large Magellanic Cloud (LMC) has been discovered to be modulated with a 10.3-day period, making it the first extra-galactic γ-ray binary. Aim. This work aims at the detection of very-high-energy (VHE, >100 GeV) γ-ray emission and the search for modulation of the VHE signal with the orbital period of the binary system. Methods. LMC P3 has been observed with the High Energy Stereoscopic System (H.E.S.S.); the acceptance-corrected exposure time is 100 h. The data set has been folded with the known orbital period of the system in order to test for variability of the emission. Results. VHE γ-ray emission is detected with a statistical significance of 6.4 σ. The data clearly show variability which is phase-locked to the orbital period of the system. Periodicity cannot be deduced from the H.E.S.S. data set alone. The orbit-averaged luminosity in the 1–10 TeV energy range is (1.4 ± 0.2) × 1035 erg s−1. A luminosity of (5 ± 1) × 1035 erg s−1 is reached during 20% of the orbit. HE and VHE γ-ray emissions are anti-correlated. LMC P3 is the most luminous γ-ray binary known so far.

scholarly journals Very high energy γ-ray emission from two blazars of unknown redshift and upper limits on their distance

2020 ◽  
Vol 494 (4) ◽  
pp. 5590-5602
Author(s):  
H Abdalla ◽  
R Adam ◽  
F Aharonian ◽  
F Ait Benkhali ◽  
E O Angüner ◽  
...  
Keyword(s):  
Confidence Level ◽  
High Energy ◽  
Bl Lac Objects ◽  
Upper Limit ◽  
Upper Limits ◽  
Bl Lac ◽  
Very High Energy ◽  
Stereoscopic System ◽  
Γ Ray ◽  
Very High

ABSTRACT We report on the detection of very high energy (VHE; E > 100 GeV) γ-ray emission from the BL Lac objects KUV 00311−1938 and PKS 1440−389 with the High Energy Stereoscopic System (H.E.S.S.). H.E.S.S. observations were accompanied or preceded by multiwavelength observations with Fermi/LAT, XRT and UVOT onboard the Swift satellite, and ATOM. Based on an extrapolation of the Fermi/LAT spectrum towards the VHE γ-ray regime, we deduce a 95 per cent confidence level upper limit on the unknown redshift of KUV 00311−1938 of $z$ < 0.98 and of PKS 1440−389 of $z$ < 0.53. When combined with previous spectroscopy results, the redshift of KUV 00311−1938 is constrained to 0.51 ≤ $z$ < 0.98 and of PKS 1440−389 to 0.14 ⪅ $z$ < 0.53.

scholarly journals Fermi LARGE AREA TELESCOPE DETECTION OF TWO VERY-HIGH-ENERGY ( E > 100 GeV) γ-RAY PHOTONS FROM THE z = 1.1 BLAZAR PKS 0426–380

2013 ◽  
Vol 777 (1) ◽  
pp. L18 ◽  
Author(s):  
Y. T. Tanaka ◽  
C. C. Cheung ◽  
Y. Inoue ◽  
Ł. Stawarz ◽  
M. Ajello ◽  
...  
Keyword(s):  
High Energy ◽  
Large Area ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

scholarly journals A Very High Energy γ-Ray Survey toward the Cygnus Region of the Galaxy

2018 ◽  
Vol 861 (2) ◽  
pp. 134 ◽  
Author(s):  
A. U. Abeysekara ◽  
A. Archer ◽  
T. Aune ◽  
W. Benbow ◽  
R. Bird ◽  
...  
Keyword(s):  
High Energy ◽  
The Galaxy ◽  
Very High Energy ◽  
Γ Ray ◽  
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 DISCOVERY OF HIGH-ENERGY AND VERY HIGH ENERGY γ-RAY EMISSION FROM THE BLAZAR RBS 0413

2012 ◽  
Vol 750 (2) ◽  
pp. 94 ◽  
Author(s):  
E. Aliu ◽  
S. Archambault ◽  
T. Arlen ◽  
T. Aune ◽  
M. Beilicke ◽  
...  
Keyword(s):  
High Energy ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

scholarly journals PERIODIC VERY HIGH ENERGY γ-RAY EMISSION FROM LS I +61°303 OBSERVED WITH THE MAGIC TELESCOPE

2009 ◽  
Vol 693 (1) ◽  
pp. 303-310 ◽  
Author(s):  
J. Albert ◽  
E. Aliu ◽  
H. Anderhub ◽  
L. A. Antonelli ◽  
P. Antoranz ◽  
...  
Keyword(s):  
High Energy ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

scholarly journals Detection of very-high-energy γ-ray emission from the colliding wind binary η Car with H.E.S.S.

2020 ◽  
Vol 635 ◽  
pp. A167 ◽  
Author(s):  
◽  
H. Abdalla ◽  
R. Adam ◽  
F. Aharonian ◽  
F. Ait Benkhali ◽  
...  
Keyword(s):  
Binary Systems ◽  
High Energy ◽  
Emission Region ◽  
Reconstructed Signal ◽  
Additional Noise ◽  
Before And After ◽  
Orbital Phase ◽  
Very High Energy ◽  
Stereoscopic System ◽  
Very High

Aims. Colliding wind binary systems have long been suspected to be high-energy (HE; 100 MeV < E < 100 GeV) γ-ray emitters. η Car is the most prominent member of this object class and is confirmed to emit phase-locked HE γ rays from hundreds of MeV to ~100 GeV energies. This work aims to search for and characterise the very-high-energy (VHE; E >100 GeV) γ-ray emission from η Car around the last periastron passage in 2014 with the ground-based High Energy Stereoscopic System (H.E.S.S.). Methods. The region around η Car was observed with H.E.S.S. between orbital phase p = 0.78−1.10, with a closer sampling at p ≈ 0.95 and p ≈ 1.10 (assuming a period of 2023 days). Optimised hardware settings as well as adjustments to the data reduction, reconstruction, and signal selection were needed to suppress and take into account the strong, extended, and inhomogeneous night sky background (NSB) in the η Car field of view. Tailored run-wise Monte-Carlo simulations (RWS) were required to accurately treat the additional noise from NSB photons in the instrument response functions. Results. H.E.S.S. detected VHE γ-ray emission from the direction of η Car shortly before and after the minimum in the X-ray light-curve close to periastron. Using the point spread function provided by RWS, the reconstructed signal is point-like and the spectrum is best described by a power law. The overall flux and spectral index in VHE γ rays agree within statistical and systematic errors before and after periastron. The γ-ray spectrum extends up to at least ~400 GeV. This implies a maximum magnetic field in a leptonic scenario in the emission region of 0.5 Gauss. No indication for phase-locked flux variations is detected in the H.E.S.S. data.

scholarly journals Detection of extended very-high-energy γ-ray emission towards the young stellar cluster Westerlund 2

2007 ◽  
Vol 467 (3) ◽  
pp. 1075-1080 ◽  
Author(s):  
F. Aharonian ◽  
A. G. Akhperjanian ◽  
A. R. Bazer-Bachi ◽  
M. Beilicke ◽  
W. Benbow ◽  
...  
Keyword(s):  
High Energy ◽  
Stellar Cluster ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

scholarly journals Very High Energy γ-Ray Generation Near The Light Cylinder of an Axisymmetric Rotator: Cos-B Like γ-Ray Sources

1992 ◽  
Vol 128 ◽  
pp. 207-208
Author(s):  
S. V. Bogovalov ◽  
YU. D. Kotov
Keyword(s):  
High Energy ◽  
Relativistic Electrons ◽  
X Rays ◽  
Inverse Compton Scattering ◽  
Light Cylinder ◽  
Radiation Spectra ◽  
Inverse Compton ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

AbstractSuper-hard γ-ray radiation spectra have been calculated. This radiation is generated near the velocity-of-light cylinder through the process of inverse-Compton scattering of relativistic electrons by thermal photons radiated by a neutron star. These calculations have been compared with observations of the Crab and Vela pulsars at 1000-GeV γ-ray energies. A correlation between γ-ray flares and those in soft (Ex ≃ lkeV) X-rays are predicted.

scholarly journals Long-term multiwavelength view of the blazar 1ES 1218+304

2019 ◽  
Vol 489 (4) ◽  
pp. 5076-5086 ◽  
Author(s):  
K K Singh ◽  
B Bisschoff ◽  
B van Soelen ◽  
A Tolamatti ◽  
J P Marais ◽  
...  
Keyword(s):  
High Energy ◽  
Host Galaxy ◽  
Energy Bands ◽  
X Ray ◽  
Very High Energy ◽  
Γ Ray ◽  
Activity State ◽  
Low Activity ◽  
Very High

ABSTRACT In this work, we present a multiwavelength study of the blazar 1ES 1218+304 using near simultaneous observations over 10 yr during the period 2008 September 1 to 2018 August 31 (MJD 54710–58361). We have analysed data from Swift-UVOT, Swift-XRT, and Fermi-LAT to study the long term behaviour of 1ES 1218+304 in different energy bands over the last decade. We have also used the archival data from OVRO, MAXI, and Swift-BAT available during the above period. The near simultaneous data on 1ES 1218+304 suggest that the long term multiwavelength emission from the source is steady and does not show any significant change in the source activity. The optical/UV fluxes are found to be dominated by the host galaxy emission and can be modelled using the pegase code. However, the time averaged X-ray and γ-ray emissions from the source are reproduced using a single zone leptonic model with log-parabolic distribution for the radiating particles. The intrinsic very high energy γ-ray emission during a low activity state of the source is broadly consistent with the predictions of the leptonic model for blazars. We have investigated the physical properties of the jet and the mass of the supermassive black hole at the centre of the host galaxy using long term X-ray observations from the Swift-XRT which is in agreement with the value derived using blackbody approximation of the host galaxy. We also discuss the extreme nature of the source on the basis of X-ray and γ-ray observations.

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