Upper Limits on TeV Gamma-Ray Emission from Active Galactic Nuclei

1995 ◽  
Vol 452 ◽  
pp. 588 ◽  
Author(s):  
A. D. Kerrick ◽  
C. W. Akerlof ◽  
S. Biller ◽  
J. Buckley ◽  
D. A. Carter-Lewis ◽  
...  
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Upper Limits ◽  
Gamma Ray Emission

scholarly journals Gamma-Ray Emission from Extragalactic Radio Sources: EGRET Observations of Active Galactic Nuclei

1996 ◽  
Vol 175 ◽  
pp. 277-280
Author(s):  
Peter F. Michelson
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
High Energy ◽  
Radio Spectrum ◽  
Active Galaxies ◽  
Emission Characteristics ◽  
Radio Sources ◽  
Emission Models ◽  
Gamma Ray Emission

The Energetic Gamma-Ray Experiment Telescope (EGRET) on the Compton Gamma-Ray Observatory is an imaging high-energy telescope with sensitivity from approximately 20 MeV to 30 GeV. EGRET has observed more than 129 sources during more than 4 years of operation. Among these sources, 51 have been identified with active galaxies. A common characteristic of the AGN sources is that they are all radio-loud, flat radio spectrum sources. Many of them are seen as superluminal radio sources as well. The gamma-ray emission characteristics of these sources are reviewed and some of the proposed emission models are discussed.

scholarly journals Correlated neutrino and gamma-ray emission from Active Galactic Nuclei - an estimation

2012 ◽  
Vol 355 ◽  
pp. 012039 ◽  
Author(s):  
M Doert ◽  
J K Becker ◽  
F Halzen ◽  
A O'Murchadha ◽  
W Rhode
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Gamma Ray Emission

scholarly journals The IceCube neutrino observatory: latest results on the search for point sources and status of IceCube construction

2006 ◽  
Vol 2 (14) ◽  
pp. 689-692
Author(s):  
Thierry P.A. Castermans ◽  
Albrecht Karle
Keyword(s):  
Active Galactic Nuclei ◽  
Optical Sensors ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Point Sources ◽  
Upper Limits ◽  
Emission Models ◽  
X Ray Binaries ◽  
Prototype Instrument ◽  
Higher Sensitivity

AbstractThe AMANDA neutrino telescope, prototype instrument of the IceCube neutrino observatory at South Pole, has collected data since 2000 in its final configuration. A period of 1001 days of livetime between 2000 and 2004 has been analysed in order to find evidence of a neutrino signal coming from point-like sources such as microquasars, active galactic nuclei, supernovae remnants or gamma ray bursts. A sensitivity to fluxes of νμ + νμ + ντ + ντ of dΦ/dE =1.0 · 10−10 (E/TeV)−2 · TeV−1 cm−2 s−1 was reached in the energy range between 1.6 TeV and 1.6 PeV. No significant excess over the background has been found so far. Flux upper limits infered from this study can constrain certain neutrino emission models of X-ray binaries. IceCube will have a substantially higher sensitivity. Currently at 10% of its final extension, it will comprise 4800 optical sensors deployed along 80 strings by early 2011, instrumenting one cubic kilometre volume of ice and 1 km2 at the surface.

scholarly journals Radio and Gamma-ray emission in nearby BL Lacs

2013 ◽  
Vol 9 (S304) ◽  
pp. 200-203 ◽  
Author(s):  
G. Giovannini ◽  
E. Liuzzo ◽  
B. Boccardi ◽  
M. Giroletti
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Scale Structure ◽  
Bl Lac Objects ◽  
Long Baseline ◽  
Γ Ray ◽  
Gamma Ray Emission ◽  
Very Long Baseline Array ◽  
Bl Lacs

AbstractThe advent of Fermi is changing our understanding on the radio and γ-ray emission in active galactic nuclei. Unlike pre-Fermi ideas, BL Lac objects are found to be the most abundant emitters in the γ-ray band. However, since they are relatively weak radio sources, most of their parsec-scale structure and their multifrequency properties are poorly understood and/or have not been investigated in a systematic fashion. Here we are analyzing the radio and γ-ray emission properties of a sample of 42 BL Lacs selected with no constraint on their radio and γ-ray emission. Thanks to new Very Long Baseline Array observations at 8 and 15 GHz for the whole sample, we discuss their parsec-scale structure. Parsec-scale radio emission is observed in the majority of the sources at both frequencies. The comparison between our results in radio and gamma-ray bands points out the presence of a large number of faint BL Lacs showing “non-classical” properties such as low source compactness, low core dominance, no gamma-ray emission.

scholarly journals Magnetospheric Gamma-Ray Emission in Active Galactic Nuclei

2018 ◽  
Vol 852 (2) ◽  
pp. 112 ◽  
Author(s):  
Grigorios Katsoulakos ◽  
Frank M. Rieger
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Gamma Ray Emission

LIMITS TO THE PHYSICAL PARAMETERS IN EXTRAGALACTIC GAMMA-RAY SOURCES

2009 ◽  
Vol 18 (10) ◽  
pp. 1523-1527 ◽  
Author(s):  
E. V. DERISHEV
Keyword(s):  
Active Galactic Nuclei ◽  
Gamma Rays ◽  
Gamma Ray ◽  
Galactic Nuclei ◽  
Lorentz Factor ◽  
Physical Parameters ◽  
Gamma Ray Burst ◽  
Upper Limits

We examine several constraints on the physical parameters in active galactic nuclei and gamma-ray burst, originating from the assumption that these sources are efficient in converting their energy into gamma-rays. It is shown that in most cases these constraints may be reformulated in terms of bounds on the jet Lorentz factor, for which both the lower and the upper limits can be evaluated.

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