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Discovery of VHE gamma-rays from the distant BL Lacertae 1ES 0347-121
- Source :
- Astronomy and Astrophysics-A&A, Astronomy and Astrophysics-A&A, EDP Sciences, 2007, 473, pp.L25-L28. ⟨10.1051/0004-6361:20078412⟩, Astronomy and Astrophysics-A&A, 2007, 473, pp.L25-L28. ⟨10.1051/0004-6361:20078412⟩
- Publication Year :
- 2007
- Publisher :
- HAL CCSD, 2007.
-
Abstract
- Aims.Our aim is to study the production mechanism for very-high-energy (VHE; >100 GeV) ?-rays in distant active galactic nuclei (AGN) and use the observed VHE spectrum to derive limits on the Extragalactic Background Light (EBL). We also want to determine physical quantities through the modeling of the object's broad-band spectral energy distribution (SED). Methods: VHE observations (~25 h live time) of the BL Lac 1ES 0347-121 (redshift z = 0.188) were conducted with the High Energy Stereoscopic System (HESS) between August and December 2006. Contemporaneous X-ray and UV/optical observations from the SWIFT satellite are used to interpret the SED of the source in terms of a synchrotron self Compton (SSC) model. Results: An excess of 327 events, corresponding to a statistical significance of 10.1 standard deviations, is detected from 1ES 0347-121. Its photon spectrum, ranging from ~250 GeV to ~3 TeV, is well described by a power law with a photon index of ? = 3.10 ± 0.23stat ± 0.10sys. The integral flux above 250 GeV corresponds to ~2% of the flux of the Crab Nebula above the same threshold. No VHE flux variability is detected within the data set. Conclusions: Constraints on the EBL density at optical to near-infrared wavelengths derived from the photon spectrum of 1ES 0347-121 are close to the strongest limits derived previously. The strong EBL limits confirm earlier findings, that the EBL density in the near-infrared is close to the lower limits from source counts. This implies that the universe is more transparent to VHE ?-rays than previously believed. An SSC model provides a reasonable description of the contemporaneous SED. Affiliations are only available in electronic form at http://www.aanda.org
- Subjects :
- Active galactic nucleus
[SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
Astrophysics::High Energy Astrophysical Phenomena
galaxies: active
Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
01 natural sciences
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
0103 physical sciences
High Energy Stereoscopic System
Source counts
010303 astronomy & astrophysics
cosmology: diffuse radiation
Physics
galaxies: BL Lacertae objects: individual: 1ES0347-121
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
010308 nuclear & particles physics
Gamma ray
Astronomy
Astronomy and Astrophysics
Redshift
Crab Nebula
Extragalactic background light
Space and Planetary Science
galaxies: BL Lacertae objects: general
Spectral energy distribution
gamma rays: observations
Subjects
Details
- Language :
- English
- ISSN :
- 00046361
- Database :
- OpenAIRE
- Journal :
- Astronomy and Astrophysics-A&A, Astronomy and Astrophysics-A&A, EDP Sciences, 2007, 473, pp.L25-L28. ⟨10.1051/0004-6361:20078412⟩, Astronomy and Astrophysics-A&A, 2007, 473, pp.L25-L28. ⟨10.1051/0004-6361:20078412⟩
- Accession number :
- edsair.doi.dedup.....001914fad3579314d4f91559419ef2e8