The intermediate-frequency peaked BL Lacertae (IBL) object 3C 66A is detected during 2007-2008 in VHE (very high energy; E > 100 GeV) γ rays with the VERITAS stereoscopic array of imaging atmospheric Cherenkov telescopes. An excess of 1791 events is detected, corresponding to a significance of 21.2 standard deviations (σ), in these observations (32.8 hr live time). The observed integral flux above 200 GeV is 6% of the Crab Nebula's flux and shows evidence for variability on the timescale of days. The measured energy spectrum is characterized by a soft power law with photon index Γ = 4.1 ± 0.4stat ± 0.6sys. The radio galaxy 3C 66B is excluded as a possible source of the VHE emission.
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Titolo: | VERITAS OBSERVATIONS OF A VERY HIGH ENERGY γ-RAY FLARE FROM THE BLAZAR 3C 66A |
Autori: | Cesarini, Andrea; Veritas, Collaboration |
Autori Unitn: | |
Titolo del periodico: | THE ASTROPHYSICAL JOURNAL |
Anno di pubblicazione: | 2009 |
Numero e parte del fascicolo: | 2 |
Codice identificativo Scopus: | 2-s2.0-64849092339 |
Codice identificativo ISI: | WOS:000264196400012 |
Digital Object Identifier (DOI): | http://dx.doi.org/10.1088/0004-637X/693/2/L104 |
Handle: | http://hdl.handle.net/11572/100167 |
Appare nelle tipologie: | 03.1 Articolo su rivista (Journal article) |