A Search for Very High Energy Gamma Rays from Active Galactic Nuclei Visible from the Southern Hemisphere

Chadwick, P. M.; Lyons, K.; McComb, T. J. L.; Orford, K. J.; Osborne, J. L.; Rayner, S. M.; Shaw, S. E.; Turver, K. E.

doi:10.1086/307597

Cited by 11 publications

(9 citation statements)

References 31 publications

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“…Several authors have concluded from the broadband characteristics of 1ES 1101-232 that this source is expected to emit VHE γ-ray emission at flux levels detectable by instruments like HESS (e.g., Wolter et al 2000;. Previous VHE observations with the Durham Mark 6 telescope in 1998 have only yielded flux limits (Chadwick et al 1999). Also, in the GeV γ-ray domain, EGRET did not detect emission from 1ES 1101-232 (Lin et al 1996).…”

Section: The Hbl Object 1es 1101-232mentioning

confidence: 98%

Detection of VHE gamma-ray emission from the distant blazar 1ES 1101-232 with HESS and broadband characterisation

Aharonian

Akhperjanian

Bazer‐Bachi

et al. 2007

A&A

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119

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Context. The blazar 1ES 1101-232 was observed with the High Energy Stereoscopic System (HESS) of Atmospheric Cherenkov Telescopes (ACT) in 2004 and 2005, for a live time of 43 h. VHE (E > 10 11 eV) γ-rays were detected for the first time from this object. Aims. VHE observations of blazars are used to investigate the inner parts of the blazar jets, and also to study the extragalactic background light (EBL) in the near-infrared band. Methods. Observations in 2005 were conducted in a multiwavelength campaign, together with the RXTE satellite and optical observations. In 2004, simultaneous observations with XMM-Newton were obtained. Results. 1ES 1101-232 was detected with HESS with an excess of 649 photons, at a significance of 10σ. The measured VHE γ-ray flux amounts to dN/dE = (5.63 ± 0.89) × 10 −13 (E/TeV) −(2.94±0.20) cm −2 s −1 TeV −1 , above a spectral energy threshold of 225 GeV. No significant variation of the VHE γ-ray flux on any time scale was found. 1ES 1101-232 exhibits a very hard spectrum, and at a redshift of z = 0.186, is the blazar with the highest confirmed redshift detected in VHE γ-rays so far. Conclusions. The data allow the construction of truly simultaneous spectral energy distributions of the source, from the optical to the VHE band. Using an EBL model with νF ν = 14 nWm −2 sr −1 at 1.5 µm as presented in Aharonian et al. (2006a) suggests an intrinsic VHE power output peak of the source at above 3 TeV.

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Section: The Hbl Object 1es 1101-232mentioning

confidence: 98%

Detection of VHE gamma-ray emission from the distant blazar 1ES 1101-232 with HESS and broadband characterisation

Aharonian

Akhperjanian

Bazer‐Bachi

et al. 2007

A&A

Self Cite

119

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“…Consistent with these expectations, BL Lacs are the only type of blazars detected at very high energies (VHE,E 250 GeV). Currently, six BL Lacs are confirmed sources of VHE gamma rays, Mrk 421 (Punch et al 1992), Mrk 501 (Quinn et al 1996), H 1426+428 (Horan et al 2002) and 1ES 1959+650 (Nishiyama et al 2000; the original detection of the nearby BL Lac, 1ES 2344+514 (Catanese et al 1998) was confirmed by the HEGRA group (Tluczykont et al 2003) while that of the Southern Hemisphere BL Lac, PKS 2155-304 (Chadwick et al 1999) was confirmed recently by H.E.S.S. (Djannati-Atai et al 2003).…”

Section: Introductionmentioning

confidence: 99%

Constraints on the Very High Energy Emission from BL Lacertae Objects

Horan

Badran

Bond

et al. 2004

ApJ

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We present results from observations of 29 BL Lacertae objects, taken with the Whipple Observatory 10 m Gamma-Ray Telescope between 1995 and 2000. The observed objects are mostly at low redshift (z < 0.2) but observations of objects of z up to 0.444 are also reported. Five of the objects are EGRET sources and two are unconfirmed TeV sources. Three of the confirmed sources of extragalactic TeV gamma rays were originally observed as part of this survey and have been reported elsewhere. No significant excesses are detected from any of the other objects observed, on time scales of days, months or years. We report 99.9% confidence level flux upper limits for the objects for each observing season. The flux upper limits are typically 20% of the Crab flux although, for some sources, limits as sensitive as 6% of the Crab flux were derived. The results are consistent with the synchrotron-self-Compton (SSC) model predictions considered in this work.Comment: 30 pages, 9 Tables, 3 Figures, accepted for publication in the Astrophysical Journal, 1 March 2003 edition Version 2 contains four corrections to the flux units (Tables 5, 6, 7 and 9) and two corrections to upper limits in the flux units column for H1426+428 in Table

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“…Possible variability of the gammaray signal (Grindlay et al 1975a), coupled with theoretical modelling, also excluded the inner radio lobes as the gamma-ray source, with a proposed model of the gammaray flux arising from inverse Compton scattering in the nucleus of Cen A being favoured (Grindlay 1975 (Carramiñana et al 1990). In March 1997, 6.75 h of observations were made with the Durham Mk6 telescope, which provided better discrimination against the cosmic-ray background, with a 3s flux upper limit above 300 GeV of 5.2 Â 10 À11 cm À2 s À1 (Chadwick et al 1999).…”

Section: Searches At Tev Energiesmentioning

confidence: 99%

Centaurus A at Ultra-High Energies

Clay

Whelan

Edwards

2010

Publ. – Astron. Soc. Aust

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Abstract:We review the importance of Centaurus A in high-energy astrophysics as a nearby object with many of the properties expected of a major source of very high-energy cosmic rays and gamma rays. We examine observational techniques and the results so far obtained in the energy range from 200 GeV to above 100 EeV and attempt to fit those data to expectations of Centaurus A as an astrophysical source from very high to ultra-high energies.

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A Search for Very High Energy Gamma Rays from Active Galactic Nuclei Visible from the Southern Hemisphere

Cited by 11 publications

References 31 publications

Detection of VHE gamma-ray emission from the distant blazar 1ES 1101-232 with HESS and broadband characterisation

Detection of VHE gamma-ray emission from the distant blazar 1ES 1101-232 with HESS and broadband characterisation

Constraints on the Very High Energy Emission from BL Lacertae Objects

Centaurus A at Ultra-High Energies

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