Details

Autor(en) / Beteiligte

• Djannati-Ataï, A.
• Khelifi, B.
• Vorobiov, S.
• Bazer-Bachi, R.
• Chounet, L. M.
• Debiais, G.
• Degrange, B.
• Espigat, P.
• Fabre, B.
• Fontaine, G.
• Goret, P.
• Gouiffes, C.
• Masterson, C.
• Piron, F.
• Punch, M.
• Rivoal, M.
• Rob, L.
• Tavernet, J.-P.

Titel

Detection of the BL Lac object 1ES 1426+428 in the Very High Energy gamma-ray band by the CAT Telescope from 1998–2000

Ist Teil von

• Astronomy and astrophysics (Berlin), 2002-09, Vol.391 (3), p.L25-L28

Ort / Verlag

EDP Sciences

Erscheinungsjahr

2002

Link zum Volltext

Quelle

EZB Free E-Journals

Beschreibungen/Notizen

• The BL Lac Object 1ES 1426+428, at a red-shift of $z=0.129$, has been monitored by the Cat telescope from February 1998 to June 2000. The accumulation of 26 h of observations shows a γ-ray signal of 321 events above $250\:{\rm GeV}$ at 5.2 standard deviations, determined using data analysis cuts adapted to a weak, steep-spectrum source. The source emission has an average flux of ${\Phi}_{\rm diff}({400\:{\rm GeV}})=6.73\pm1.27^{\rm stat}\pm1.45^{\rm syst}\times10^{-11}\:{\rm cm^{-2}\:s^{-1}\,TeV^{-1}}$, and a very steep spectrum, with a differential spectral index of $\gamma=-3.60 \pm 0.57$ which can be refined to $\gamma=-3.66 \pm 0.41$ using a higher flux data subset. If, as expected from its broad-band properties, the Very High Energy emission is hard at the source, these observations support a strong absorption effect of γ-rays by the Intergalactic Infrared field.