A low density of the Extragalactic Background Light revealed by the H.E.S.S. spectra of the BLLac objects 1ES 1101-232 and H 2356-309

Abstract

The unexpectedly hard spectra measured by HESS for the BLLacs 1ES 1101-232 and H 2356-309 has allowed an upper limit on the Extragalactic Background Light (EBL) to be derived in the optical/near-infrared range, which is very close to the lower limit given by the resolved galaxy counts. This result seems to exclude a large contribution to the EBL from other sources (e.g. Population III stars) and indicates that the intergalactic space is more transparent to gamma-rays than previously thought. A brief discussion of EBL absorption effects on blazar spectra and further observational tests to check this conclusion are presented, including the selection of new candidates for observations with Cherenkov telescopes.

arXiv comment6 pages, 9 figures, 1 table. Proceedings of the conference "The Multi-Messenger Approach to High-Energy Gamma-ray Sources", Barcelona, July 4-7 2006

References in corpus (19)

• A theoretical unifying scheme for gamma-ray bright blazars
• The Cosmic Infrared Background: Measurements and Implications
• A low level of extragalactic background light as revealed by gamma-rays from blazars
• The Cosmic Infrared Background Resolved by Spitzer. Contributions of Mid-Infrared Galaxies to the Far-Infrared Background
• The Bulk of the Cosmic Infrared Background Resolved by ISOCAM
• TeV candidate BL Lac objects
• The Contribution of the First Stars to the Cosmic Infrared Background
• H.E.S.S. Observations of PKS 2155-304
• The First Detections of the Extragalactic Background Light at 3000, 5500, and 8000A (I): Results
• Hard TeV spectra of blazars and the constraints to the IR intergalactic background
• Population III and the Near-Infrared Background Excess
• The Blazar Sequence: Validity and Predictions
• Observations of H1426+428 with HEGRA -- Observations in 2002 and reanalysis of 1999&2000 data
• The Near Infrared Background: Interplanetary Dust or Primordial Stars?
• Comments on ``The first detections of the Extragalactic Background Light at 3000, 5500, and 8000 A'' by Bernstein, Freedman and Madore
• TeV blazar gamma-ray emission produced by a cooling pile-up particle energy distribution function
• Probing Galaxy Formation with High Energy Gamma-Rays
• Constraining the Cosmic Background Light with four BL Lac TeV spectra
• X-ray variability and prediction of TeV emission in the HBL 1ES1101-232

Cited by in corpus (6)

• The Blazar Sequence: Validity and Predictions
• Gamma-rays from Blazars and the Extragalactic Background Light
• Upper limits from five years of blazar observations with the VERITAS Cherenkov telescopes
• TeV and keV-MeV Excesses as Probes for Hadronic Process in BL Lacertaes
• The nature of the intrinsic spectra from the VHE emission of H 2356-309 and 1ES 1101-232
• Constraints on the Optical-IR extragalactic background from gamma-ray absorption studies