Multiwavelength observations of the binary system PSR B1259−63/LS 2883 around the 2010–2011 periastron passage

Abstract

We report on broad multiwavelength observations of the 2010–2011 periastron passage of the γ -ray loud binary system PSR B1259−63. High-resolution interferometric radio observations establish extended radio emission trailing the position of the pulsar. Observations with the Fermi Gamma-ray Space Telescope reveal GeV γ -ray flaring activity of the system, reaching the spin-down luminosity of the pulsar, around 30 d after periastron. There are no clear signatures of variability at radio, X-ray and TeV energies at the time of the GeV flare. Variability around periastron in the Hα emission line, can be interpreted as the gravitational interaction between the pulsar and the circumstellar disc. The equivalent width of the Hα grows from a few days before periastron until a few days later, and decreases again between 18 and 46 d after periastron. In near-infrared we observe the similar decrease of the equivalent width of Brγ line between the 40th and 117th day after the periastron. For the idealized disc, the variability of the Hα line represents the variability of the mass and size of the disc. We discuss possible physical relations between the state of the disc and GeV emission under assumption that GeV flare is directly related to the decrease of the disc size