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تسجيل مستخدم جديدThe variability of the quasar 3C 273: a radio to gamma-ray view
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We have analysed the first 15 months of Fermi/LAT data of the radio loud quasar 3C 273. Intense gamma-ray activity has been detected, showing an average flux of F(> 100 MeV) = 1.4e-6 ph/cm^2/s, with a peak at F(> 100 MeV) = 5.6e-6 ph/cm^2/s detected during a flare in September 2009. Together with the brightening of the source, a possible hardening of the gamma-ray spectrum is observed, pointing to a shift of the inverse Compton peak toward higher energies than the 1-10 MeV range in which 3C 273 inverse Compton emission is typically observed to peak. During the 15 months of observations the photon index is measured to vary between 2.4 and 3.3, with an average value of 2.78 +/- 0.03. When compared to the observations at other wavelengths, the gamma-rays show the largest flux variations and we discuss the possibility that two different components are responsible for the inverse Compton hump emission below and above the MeV peak.
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