Tam Pak Hin (SYSU)
The binary system PSR B1259-63/LS 2883, with an elongated orbit, is well sampled in radio, X-rays, GeV and TeV gamma-rays, and shows orbital-phase-dependent variability in these frequencies. The interaction between the stellar disk and pulsar wind can result in shock acceleration, thereby explaining the broadband emission. However, GeV flares have been detected 30-40 days after 2011, 2014, and 2017 periastron passages and is unexplained by any existing models. The major issue is the time delay of the GeV flares compared to the peak times seen in other wavelengths. In this talk, I will review the multi-wavelength observations and present the new results seen in 2017: the 2017 flares occurr at different orbital phases than previous years, and seem to contain short, fast flares. Any feasible model has to accommodate this new observation.