We present the light curves and spectral data of two exceptionally luminous gamma-ray outbursts observed by the Large Area Telescope experiment on board the Fermi Gamma-ray Space Telescope from 3C 273 in 2009 September. During these flares, having a duration of a few days, the source reached its highest gamma-ray flux ever measured. This allowed us to study, in some details, their spectral and temporal structures. The rise and the decay are asymmetric on timescales of 6 hr, and the spectral index was significantly harder during the flares than during the preceding 11 months. We also found that short, very intense flares put out the same time-integrated energy as long, less intense flares like that observed in 2009 August.
|Titolo:||Fermi-large area telescope observations of the exceptional gamma-ray outbursts of 3C 273 in 2009 September|
|Data di pubblicazione:||2010|
|Digital Object Identifier (DOI):||10.1088/2041-8205/714/1/L73|
|Appare nelle tipologie:||1.1 Articolo in rivista|