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Title: Discovery of very high energy gamma-ray emission from the low-frequency peaked BL Lacertae object BL Lacertae
Author: Paredes i Poy, Josep Maria
Ribó Gomis, Marc
Bosch i Ramon, Valentí
MAGIC Collaboration
Keywords: Astronomia de raigs gamma
Observacions astronòmiques
Gamma ray astronomy
Astronomical observations
Issue Date: 2007
Publisher: Institute of Physics (IOP)
Abstract: The MAGIC collaboration observed BL Lacertae for 22.2 hr during 2005 August to December and for 26 hr during 2006 July to September. The source is the historical prototype and eponym of a class of low-frequency-peaked BL Lacertae (LBL) objects. A very high energy (VHE) γ-ray signal was discovered with a 5.1 σ excess in the 2005 data. Above 200 GeV, an integral flux of (0.6+/-0.2)×10-11 cm-2 s-1 was measured, corresponding to approximately 3% of the Crab flux. The differential spectrum between 150 and 900 GeV is rather steep with a photon index of -3.6 +/- 0.5. The light curve shows no significant variability during the observations in 2005. For the first time a clear detection of VHE γ-ray emission from an LBL object was obtained with a signal below previous upper limits. The 2006 data show no significant excess. This drop in flux follows the observed trend in optical activity.
Note: Reproducció del document publicat a:
It is part of: Astrophysical Journal, 2007, vol. 666, p. 17-20
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ISSN: 0004-637X
Appears in Collections:Articles publicats en revistes (Física Quàntica i Astrofísica)

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