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Name:Aous Abdo


Institution:NRL


Country:USA




Title:Discovery of high energy Gamma-Ray emission from the binary system PSR B1259-63/LS 2883 around periastron with FERMI




Abstract:We report on the discovery of ≥ 100 MeV γ rays from the binary system PSR B1259−63/LS 2883 using the Large Area Telescope (LAT) on board Fermi. The system comprises a radio
pulsar in orbit around a Be star. We report on LAT observations from near apastron to ∼ 60 days after the time of periastron, tp, on 2010 December 15. No γ-ray emission was detected from this source when it was far from periastron. Faint γ-ray emission appeared as pulsar approached periastron. At ∼ tp + 30d, the ≥ 100 MeV γ-ray flux increased over a period of a few days to a peak flux 20–30 times that seen during the pre-periastron period,but with a softer spectrum. For the following month, it was seen to be variable on daily time scales, but remained at ∼ 1 − 4 × 10−6 photons cm−2 s−1 before starting to fade at ∼ tp + 57d. The total γ-ray luminosity observed during this period is comparable to the spin-down power of the pulsar. Simultaneous radio and X-ray observations of the source showed no corresponding dramatic changes in radio and X-ray flux between the pre-periastron and post-periastron flares. We discuss possible explanations for the
observed gamma-ray-only flaring of the source.









            

            
            

              

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