Observations of Selected AGN with H.E.S.S
arXiv:astro-ph/0507207 · doi:10.1051/0004-6361:20053478
Abstract
A sample of selected active galactic nuclei (AGN) was observed in 2003 and 2004 with the High Energy Stereoscopic System (H.E.S.S.), an array of imaging atmospheric-Cherenkov telescopes in Namibia. The redshifts of these candidate very-high-energy (VHE, >100 GeV) gamma-ray emitters range from z=0.00183 to z=0.333. Significant detections were already reported for some of these objects, such as PKS 2155-304 and Markarian 421. Marginal evidence (3.1 sigma) for a signal is found from large-zenith-angle observations of Markarian 501, corresponding to an integral flux of I(>1.65 TeV) = (1.5 +/- 0.6 (stat) +/- 0.3 (syst)) x 10^{-12} cm^{-2} s^{-1} or ~15% of the Crab Nebula flux. Integral flux upper limits for 19 other AGN, based on exposures of ~1 to ~8 hrs live time, and with average energy thresholds between 160 GeV and 610 GeV, range from 0.4% to 5.1% of the Crab Nebula flux. All the upper limits are the most constraining ever reported for these objects.
9 pages, 1 figure (accepted for publication in Astronomy & Astrophysics on June 16, 2005)
References in corpus (31)
- Unified Schemes for Radio-Loud Active Galactic Nuclei
- A Unified Approach to the Classical Statistical Analysis of Small Signals
- A Unifying View of the Spectral Energy Distributions of Blazars
- Calibration of cameras of the H.E.S.S. detector
- The Ionized Gas and Nuclear Environment in NGC 3783. I. Time-Averaged 900 ks Chandra Grating Spectroscopy
- Centaurus A - NGC 5128
- Hard X-ray properties of blazars
- Evidence for TeV gamma ray emission from Cassiopeia A
- TeV candidate BL Lac objects
- Very High Energy Gamma-Rays from AGN: Cascading on the Cosmic Background Radiation Fields and the Formation of Pair Halos
- Proton synchrotron radiation of large-scale jets in active galactic nuclei
- Discovery of >350 GeV Gamma Rays from the BL Lacertae Object 1ES 2344+514
- Is the Giant Radio Galaxy M87 a TeV Gamma-Ray Emitter?
- The optical system of the H.E.S.S. imaging atmospheric Cherenkov telescopes, Part I: layout and components of the system
- H.E.S.S. Observations of PKS 2155-304
- VHE Gamma Rays from PKS 2155-304
- The Trigger System of the H.E.S.S. Telescope Array
- Detection of the BL Lac Object H1426+428 at TeV Gamma Ray Energies
- Predicted Extragalactic TeV Gamma-Ray Sources
- Observations of Mkn 421 in 2004 with H.E.S.S. at large zenith angles
- GeV emission from the nearby radio galaxy Centaurus A
- Observations of 54 Active Galactic Nuclei with the HEGRA System of Cherenkov Telescopes
- Discovery of VHE Gamma Rays from PKS 2005-489
- Constraints on the Very High Energy Emission from BL Lacertae Objects
- M87: A Misaligned BL LAC?
- Upper Limits on the Extragalactic Background Light from the Gamma-Ray Spectra of Blazars
- Predictions of the High-Energy Emission from BL Lac objects: The Case of W Comae
- Search for High Energy Gamma Rays from an X-ray Selected Blazar Sample
- TeV observations of Centaurus A
- A Search for VHE Gamma Rays from AGNs Visible from the Southern Hemisphere
- X-ray Selected BL Lacs and Blazars
Cited by in corpus (45)
- Time-integrated Neutrino Source Searches with 10 years of IceCube Data
- GeV Observations of Star-forming Galaxies with \textit{Fermi} LAT
- New constraints on the Mid-IR EBL from the HESS discovery of VHE gamma rays from 1ES 0229+200
- Discovery of very high energy gamma-ray emission from Centaurus A with H.E.S.S
- The VLBA Imaging and Polarimetry Survey at 5 GHz
- High-energy particle acceleration at the radio-lobe shock of Centaurus A
- Fermi observations of TeV-selected AGN
- High-energy Particle Acceleration and Production of Ultra-high-energy Cosmic Rays in the Giant Lobes of Centaurus A
- A synchrotron self-Compton scenario for the very high energy gamma-ray emission of the radiogalaxy M87
- Constraints on gamma-ray and neutrino emission from NGC 1068 with the MAGIC telescopes
- Evidence for VHE Gamma-ray Emission from the Distant BL Lac PG 1553+113
- High energy radiation from Centaurus A
- Detection of Intra-day Variability Timescales of Four High Energy Peaked Blazars with XMM-Newton
- Flux upper limits for 47 AGN observed with H.E.S.S. in 2004-2011
- Synoptic studies of seventeen blazars detected in very high-energy gamma-rays
- Quasar X-ray jets: Gamma-ray diagnostics of the synchrotron and inverse Compton hypotheses, the case of 3C 273
- Fermi Rules Out the IC/CMB Model for the Large Scale Jet X-ray Emission of 3C 273
- Ultra-high energy Neutrinos from Centaurus A and the Auger hot spot
- Are Starburst Galaxies Proton Calorimeters?
- High-Energy Aspects of Astrophysical Jets
- Upper Limits from HESS AGN Observations in 2005-2007
- Evidence for the Secondary Emission as the Origin of Hard Spectra in TeV Blazars
- Absorption of Nuclear Gamma-rays on the Starlight Radiation in FR I Sources: the Case of Centaurus A
- Upper limits from five years of blazar observations with the VERITAS Cherenkov telescopes
- Discovery of VHE gamma-rays from the BL Lac object PKS 0548-322
- Neutrino, -ray and cosmic ray fluxes from the core of the closest radio galaxies
- Gamma-ray fluxes from the core emission of Centaurus A: A puzzle solved
- CANGAROO-III Search for Gamma Rays from Centaurus A and the Centauri Region
- A Structured Leptonic Jet Model of the "Orphan" TeV Gamma-Ray Flares in TeV Blazars
- Very High Energy gamma-ray observations of Mrk 501 using TACTIC imaging gamma-ray telescope during 2005-06
- Extragalactic Observatory Science with the ASTRI Mini-Array at the Observatorio del Teide
- X-ray and TeV Gamma-Ray Emission from Parallel Electron-Positron or Electron-Proton Beams in BL Lac Objects
- An original constraint on the Hubble constant: h>0.74
- Constraining the contribution of Seyfert galaxies to the diffuse neutrino flux in light of point source observations
- Gamma Rays from Centaurus A
- Constraining the Emission Properties of TeV Blazar H1426+428 by the Synchrotron-Self-Compton Model
- IceCube Science
- A gamma-ray signature of energetic sources of cosmic-ray nuclei
- A Statistical Description of AGN Jet Evolution from the VLBA Imaging and Polarimetry Survey (VIPS)
- Recent Topics on Very High Energy Gamma-ray Astronomy
- Evaluation of Hadronic Emission in Starburst Galaxies and Star-forming Galaxies
- Probing Lorentz Invariance at EeV Energy
- Neutrino production from photo-hadronic interactions of the gamma flux from Active Galactic Nuclei with their gas content
- Cosmic connections: from cosmic rays to gamma rays, to cosmic backgrounds and magnetic fields
- A Modified Stratified Model for 3C 273 Jet