Author(s): A. Abdo A., Ackermann M., Ajello M., Baldini L., Ballet J., Bregeon J., Bruel P., M. Casandjian J., Charles E., Cohen-Tanugi J., Costamante L., Dumora D., Farnier C., J. Fegan S., A. Grenier I., Grondin M.-H., Guiriec Sylvain, B. Hill A., Horan D., Knodlseder J., Lemoine-Goumard M., Lott B., Nuss E., Pelassa V., Piron F., D. Scargle J., Sgro C., Starck J.-L., Tibaldo L., Vilchez N.
(Article) Published:
The Astrophysical Journal / The Astrophysical Journal Letters, vol. 714 p.L73-L78 (2010)
Links openAccess full text : 
Ref HAL: in2p3-00483105_v1
DOI: 10.1088/2041-8205/714/1/L73
Exporter : BibTex | endNote
45 citations
Abstract:
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 γ -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.