scholarly journals Optical Monitoring of the Gamma–Ray Loud BL Lac Object S5 0716+714

1996 ◽  
Vol 175 ◽  
pp. 289-290
Author(s):  
G. Latini ◽  
S. Bosio ◽  
G. DE FRANCESCO ◽  
M. Villata ◽  
G. Ghisellini ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Optical Monitoring ◽  
Bl Lac ◽  
Complete Set ◽  
Γ Ray

We monitored the γ-ray loud BL Lac object S5 0716+714 between November 1994 and April 1995 (J.D. 2449671–2449838), from the Observatories of Torino, Perugia and Roma. The source was always active in the R and B bands, showing a particularly high optical state during the period of the CGRO pointing (February 14–28, 1995). The lightcurve in the R band is presented in Fig. 1. The complete set of observations is discussed in Ghisellini et al. (1995).

scholarly journals Gamma-ray counterparts of 2WHSP high-synchrotron-peaked BL Lac objects as possible signatures of ultra-high-energy cosmic ray emission

2020 ◽  
Vol 497 (2) ◽  
pp. 2455-2468
Author(s):  
Michael W Toomey ◽  
Foteini Oikonomou ◽  
Kohta Murase
Keyword(s):  
Energy Range ◽  
Gamma Ray ◽  
Cosmic Ray ◽  
High Energy ◽  
Potential Candidate ◽  
Ultra High Energy ◽  
Bl Lac Objects ◽  
Cherenkov Telescopes ◽  
Bl Lac ◽  
Γ Ray

ABSTRACT We present a search for high-energy γ-ray emission from 566 Active Galactic Nuclei at redshift z > 0.2, from the 2WHSP catalogue of high-synchrotron peaked BL Lac objects with 8 yr of Fermi-LAT data. We focus on a redshift range where electromagnetic cascade emission induced by ultra-high-energy cosmic rays can be distinguished from leptonic emission based on the spectral properties of the sources. Our analysis leads to the detection of 160 sources above ≈5σ (TS ≥25) in the 1–300 GeV energy range. By discriminating significant sources based on their γ-ray fluxes, variability properties, and photon index in the Fermi-LAT energy range, and modelling the expected hadronic signal in the TeV regime, we select a list of promising sources as potential candidate ultra-high-energy cosmic ray emitters for follow-up observations by Imaging Atmospheric Cherenkov Telescopes.

scholarly journals Optical Monitoring of Gamma-Ray Loud Blazars

1996 ◽  
Vol 175 ◽  
pp. 287-288
Author(s):  
C.M. Raiteri ◽  
G. Ghisellini ◽  
M. Villata ◽  
G. DE FRANCESCO ◽  
S. Bosio ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Energy ◽  
Significant Fraction ◽  
Optical Monitoring ◽  
Inverse Compton ◽  
Theoretical Predictions ◽  
Γ Ray ◽  
Uv Photons ◽  
High Energy Particles ◽  
Crucial Test

The observations by the Compton Gamma Ray Observatory (CGRO) have shown that highly variable and radio-loud quasars emit a significant fraction of their energy in the γ band. According to the Inverse Compton model, the γ-ray emission is due to upscattering of soft (IR-optical-UV) photons by high energy particles. Optical monitoring is thus of great value in providing information on the mechanisms that rule the production of the seed photons for the γ-ray radiation and on the γ-ray emission itself. In particular, detection of variability correlations between optical and γ-ray emissions would be a crucial test for the theoretical predictions.

Gamma-ray Emission from the γ-ray-loud BL Lac Objects

2001 ◽  
Vol 1 (6) ◽  
pp. 494-500 ◽  
Author(s):  
Guang-Zhong Xie ◽  
Ben-Zhong Dai ◽  
En-Wei Liang ◽  
Zhao-Hua Xie
Keyword(s):  
Gamma Ray ◽  
Bl Lac Objects ◽  
Bl Lac ◽  
Γ Ray ◽  
Gamma Ray Emission

Optical Monitoring of the Gamma-Ray Loud BL Lac Object S5 0716+714

1996 ◽  
pp. 289-290
Author(s):  
G. Latini ◽  
S. Bosio ◽  
G. de Francesco ◽  
M. Villata ◽  
G. Ghisellini ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Optical Monitoring ◽  
Bl Lac

scholarly journals Peculiar emission from the new VHE gamma-ray source H1722+119

2016 ◽  
Vol 12 (S324) ◽  
pp. 251-252
Author(s):  
T. Terzić ◽  
A. Stamerra ◽  
F. D'Ammando ◽  
C. M. Raiteri ◽  
M. Villata ◽  
...  
Keyword(s):  
High Activity ◽  
Energy Band ◽  
Gamma Ray ◽  
High Energy ◽  
Cherenkov Telescopes ◽  
Bl Lac ◽  
Gamma Ray Imaging ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

The BL Lac object H1722+119 was observed in the very high energy band (VHE, E > 100 GeV) by the MAGIC (Major Atmospheric Gamma-ray Imaging Cherenkov) telescopes (Aleksić et al. 2016a, b)) between 2013 May 17 and 22, following a state of high activity in the optical band measured by the KVA (Kungliga Vetenskapsakademien) telescope. Optical high states are often used to trigger MAGIC observations, which result in the VHE γ-ray signal detection (see e.g. Aleksić et al. 2015, Ahnen et al. 2016 and references therein).

scholarly journals Gamma-Ray Imaging of the Galactic Center Region

1989 ◽  
Vol 136 ◽  
pp. 581-585
Author(s):  
W. R. Cook ◽  
D. M. Palmer ◽  
T. A. Prince ◽  
S. M. Schindler ◽  
C. H. Starr ◽  
...  
Keyword(s):  
Gamma Ray ◽  
Galactic Center ◽  
Coded Aperture ◽  
Center Region ◽  
Gamma Ray Imaging ◽  
The Galaxy ◽  
Γ Ray ◽  
Luminous Objects

The Caltech imaging γ-ray telescope was launched by balloon from Alice Springs, NT, Australia and performed observations of the galactic center during the period 12.62 to 13.00 April 1988 UT. The first coded-aperture images of the galactic center region at energies above 30 keV show a single strong γ-ray source which is located 0.7±0.1° from the galactic nucleus and is tentatively identified as 1E1740.7-2942. If the source is at the distance of the galactic center, it is one of the most luminous objects in the galaxy at energies from 35 to 200 keV.

scholarly journals Molecular Clouds Observed by the EGRET Gamma-Ray Telescope

1997 ◽  
Vol 170 ◽  
pp. 22-24 ◽  
Author(s):  
Seth. W. Digel ◽  
Stanley D. Hunter ◽  
Reshmi Mukherjee ◽  
Eugéne J. de Geus ◽  
Isabelle A. Grenier ◽  
...  
Keyword(s):  
Molecular Mass ◽  
Molecular Clouds ◽  
Gamma Ray ◽  
Angular Resolution ◽  
Cosmic Ray ◽  
High Energy ◽  
Background Rejection ◽  
Γ Rays ◽  
Γ Ray ◽  
Production Mechanisms

EGRET, the high-energy γ-ray telescope on the Compton Gamma-Ray Observatory, has the sensitivity, angular resolution, and background rejection necessary to study diffuse γ-ray emission from the interstellar medium (ISM). High-energy γ rays produced in cosmic-ray (CR) interactions in the ISM can be used to determine the CR density and calibrate the CO line as a tracer of molecular mass. Dominant production mechanisms for γ rays of energies ∼30 MeV–30 GeV are the decay of pions produced in collisions of CR protons with ambient matter and Bremsstrahlung scattering of CR electrons.

VERITAS OBSERVATIONS OF RELATIVISTIC OUTFLOWS IN LOW- AND INTERMEDIATE-FREQUENCY-PEAKED BL LAC OBJECTS

2014 ◽  
Vol 28 ◽  
pp. 1460178
Author(s):  
◽  
HEIKE PROKOPH
Keyword(s):  
Gamma Ray ◽  
Intermediate Frequency ◽  
Bl Lac Objects ◽  
Bl Lacertae ◽  
Bl Lac ◽  
Bl Lacs ◽  
Gamma Ray Telescopes ◽  
Very High

The majority of blazars detected at very high energies (VHE; E > 100 GeV) are high-frequency-peaked BL Lac objects (HBLs). Low- and intermediate-frequency-peaked BL Lacs (LBLs/IBLs with synchrotron-peak frequencies in the infrared and optical regime) are generally more powerful, more luminous, and have a richer jet environment than HBLs. However, only a handful of these IBL and LBLs have been detected by ground-based gamma-ray telescopes, typically during high-flux states. The VERITAS array has been monitoring five known VHE LBLs/IBLs since 2009: 3C 66A, W Comae, PKS 1424+240, S5 0716+714 and BL Lacertae, with typical exposures of 5-10 hours per year. The results of these long-term observations are presented, including a bright, subhour-scale VHE flare of BL Lacertae in June 2011, the first low-state detections of 3C 66A and W Comae, and the detection and characterization of the IBL B2 1215+30.

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