scholarly journals Gamma Ray Sky Surveys

1998 ◽  
Vol 179 ◽  
pp. 69-77
Author(s):  
N. Gehrels
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Energy Bands ◽  
Sky Surveys ◽  
X Ray ◽  
High Energy Gamma ◽  
Limited Energy ◽  
Energy Gamma

Prior to the current Compton Gamma Ray Observatory (Compton) mission, no comprehensive all-sky gamma-ray surveys had been performed. There were, however, some surveys performed over limited energy bands and/or over portions of the sky. These include the HEAO-A4 hard X-ray survey and the COS-B and SAS-2 high-energy gamma-ray surveys. The early work forms a basis for understanding and appreciating the Compton results, and so is reviewed in Section 2.

Evidence for ultra-high-energy gamma-ray emission from the low-mass X-ray binary 2A 1822-37.1

1989 ◽  
Vol 346 ◽  
pp. 151 ◽  
Author(s):  
D. Ciampa ◽  
R. W. Clay ◽  
P. G. Edwards
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Ultra High Energy ◽  
X Ray ◽  
High Energy Gamma ◽  
Energy Gamma ◽  
Low Mass ◽  
Gamma Ray Emission

X-ray and very high energy gamma-ray emission from Mrk 421 during 2005

Astrophysics ◽  
2010 ◽  
Vol 53 (3) ◽  
pp. 351-356
Author(s):  
V. V. Fidelis ◽  
S. A. Kalita
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
X Ray ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Gamma Ray Emission ◽  
Very High

scholarly journals A Possible X‐Ray and Radio Counterpart of the High‐Energy Gamma‐Ray Source 3EG J2227+6122

2001 ◽  
Vol 547 (1) ◽  
pp. 323-333 ◽  
Author(s):  
J. P. Halpern ◽  
E. V. Gotthelf ◽  
K. M. Leighly ◽  
D. J. Helfand
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
X Ray ◽  
High Energy Gamma ◽  
Energy Gamma

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.

scholarly journals Less noticeable shallow decay phase in early X-ray afterglows of GeV/TeV-detected gamma-ray bursts

2020 ◽  
Vol 494 (4) ◽  
pp. 5259-5269 ◽  
Author(s):  
Ryo Yamazaki ◽  
Yuri Sato ◽  
Takanori Sakamoto ◽  
Motoko Serino
Keyword(s):  
Power Law ◽  
Gamma Ray ◽  
High Energy ◽  
Decay Phase ◽  
Power Law Model ◽  
X Ray ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

ABSTRACT The nature of the shallow decay phase in the X-ray afterglow of the gamma-ray burst (GRB) is not yet clarified. We analyse the data of early X-ray afterglows of 26 GRBs triggered by Burst Alert Telescope onboard Neil Gehrels Swift Observatory and subsequently detected by Fermi Large Area Telescope (LAT) and/or Imaging Atmospheric Cherenkov Telescopes. It is found that nine events (including two out of three very-high-energy gamma-ray events) have no shallow decay phase and that their X-ray afterglow light curves are well described by single power-law model except for the jet break at later epoch. The rest are fitted by double power-law model and have a break in the early epoch (around ks), however, eight events (including a very-high-energy gamma-ray event) have the pre-break decay index larger than 0.7. We also analyse the data of well-sampled X-ray afterglows of GRBs without LAT detection and compare their decay properties with those of high-energy and very-high-energy gamma-ray events. It is found that for the GeV/TeV bursts, the fraction of events whose X-ray afterglows are described by single power law is significantly larger than those for non-GeV/TeV GRBs. Even if the GeV/TeV GRBs have shallow decay phase, their decay slope tends to be steeper than non-GeV/TeV bursts, that is, they have less noticeable shallow decay phase in the early X-ray afterglow. A possible interpretation along with the energy injection model is briefly discussed.

Period differences between X-ray and very high energy gamma-ray observations of accreting X-ray pulsars

1989 ◽  
Vol 337 ◽  
pp. L77 ◽  
Author(s):  
K. S. Cheng ◽  
Malvin Ruderman
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
X Ray ◽  
High Energy Gamma ◽  
Very High Energy ◽  
Energy Gamma ◽  
Very High

EGRET Limits on High-Energy Gamma-Ray Emission from X-Ray-- and Low-Energy Gamma-Ray--selected Seyfert Galaxies

1993 ◽  
Vol 416 ◽  
pp. L53 ◽  
Author(s):  
Y. C. Lin ◽  
D. L. Bertsch ◽  
B. L. Dingus ◽  
C. E. Fichtel ◽  
R. C. Hartman ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Seyfert Galaxies ◽  
High Energy ◽  
Low Energy ◽  
X Ray ◽  
High Energy Gamma ◽  
Energy Gamma ◽  
Gamma Ray Emission

Comparison of X-Ray– and Radio-selected BL Lacertae Objects in High-Energy Gamma-Ray Observations

1997 ◽  
Vol 476 (1) ◽  
pp. L11-L14 ◽  
Author(s):  
Y. C. Lin ◽  
D. L. Bertsch ◽  
B. L. Dingus ◽  
J. A. Esposito ◽  
C. E. Fichtel ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Bl Lacertae Objects ◽  
X Ray ◽  
Bl Lacertae ◽  
High Energy Gamma ◽  
Energy Gamma

scholarly journals Upper limits to the high-energy gamma-ray and hard X-ray flux from SN 1987A on day 55

1988 ◽  
Vol 234 (1) ◽  
pp. 73P-77P ◽  
Author(s):  
R. K. Sood ◽  
J. A. Thomas ◽  
L. Waldron ◽  
R. K. Manchanda ◽  
P. Ubertini ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
X Ray ◽  
High Energy Gamma ◽  
Sn 1987A ◽  
Upper Limits ◽  
Energy Gamma

scholarly journals SEARCH FOR HIGH-ENERGY GAMMA-RAY EMISSION FROM AN ANOMALOUS X-RAY PULSAR, 4U 0142+61

2010 ◽  
Vol 723 (1) ◽  
pp. 100-103 ◽  
Author(s):  
Sinem Şaşmaz Muş ◽  
Ersin Göğüş
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
X Ray ◽  
High Energy Gamma ◽  
Energy Gamma ◽  
Gamma Ray Emission
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