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New constraints on the Mid-IR EBL from the HESS discovery of VHE gamma rays from 1ES 0229+200
- Source :
- Astronomy and Astrophysics-A&A, Astronomy and Astrophysics-A&A, EDP Sciences, 2007, 475, pp.L9-L13. ⟨10.1051/0004-6361:20078462⟩, Astronomy and Astrophysics-A&A, 2007, 475, pp.L9-L13. ⟨10.1051/0004-6361:20078462⟩
- Publication Year :
- 2007
- Publisher :
- HAL CCSD, 2007.
-
Abstract
- AIMS: To investigate the very high energy (VHE: >100 GeV) gamma-ray emission from the high-frequency peaked BL Lac 1ES 0229+200. METHODS: Observations of 1ES 0229+200 at energies above 580 GeV were performed with the High Energy Stereoscopic System (HESS) in 2005 and 2006. RESULTS: 1ES 0229+200 is discovered by HESS to be an emitter of VHE photons. A signal is detected at the 6.6 sigma level in the HESS observations (41.8 h live time). The integral flux above 580 GeV is (9.4 +- 1.5 {stat} +- 1.9 {syst}) x 10^{-13} cm^{-2} s^{-1}, corresponding to ~1.8% of the flux observed from the Crab Nebula. The data show no evidence for significant variability on any time scale. The observed spectrum is characterized by a hard power law (Gamma = 2.50 +- 0.19 {stat} +- 0.10 {syst}) from 500 GeV to ~15 TeV. CONCLUSIONS: The high-energy range and hardness of the observed spectrum, coupled with the object's relatively large redshift (z=0.1396), enable the strongest constraints so far on the density of the Extragalactic Background Light (EBL) in the mid-infrared band. Assuming that the emitted spectrum is not harder than Gamma_{int} ~ 1.5, the HESS data support an EBL spectrum ~ lambda^{-1} and density close to the lower limit from source counts measured by Spitzer, confirming the previous indications from the HEGRA data of 1ES 1426+428 (z=0.129). Irrespective of the EBL models used, the intrinsic spectrum of 1ES 0229+200 is hard, thus locating the high-energy peak of its spectral energy distribution above a few TeV.<br />5 pages, 4 figures; Accepted for publication in A&A Letters on September 23, 2007
- Subjects :
- [SDU.ASTR.CO]Sciences of the Universe [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
Astrophysics::High Energy Astrophysical Phenomena
FOS: Physical sciences
Astrophysics
01 natural sciences
[PHYS.ASTR.CO]Physics [physics]/Astrophysics [astro-ph]/Cosmology and Extra-Galactic Astrophysics [astro-ph.CO]
0229+200
0103 physical sciences
High Energy Stereoscopic System
Source counts
010303 astronomy & astrophysics
Physics
[SDU.ASTR]Sciences of the Universe [physics]/Astrophysics [astro-ph]
010308 nuclear & particles physics
Astrophysics (astro-ph)
Gamma ray
HEGRA
Astronomy and Astrophysics
Redshift
Crab Nebula
Extragalactic background light
galaxies: BL lacertae objects: individual: 1ES
Space and Planetary Science
Spectral energy distribution
High Energy Physics::Experiment
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, 475, pp.L9-L13. ⟨10.1051/0004-6361:20078462⟩, Astronomy and Astrophysics-A&A, 2007, 475, pp.L9-L13. ⟨10.1051/0004-6361:20078462⟩
- Accession number :
- edsair.doi.dedup.....0d4ba3b1a69479b044b809ff8d0735af