Title: The X-ray emission of gamma-ray binaries as a probe of their nature

Speaker: Prof. Diego F. Torres (ICREA & Institut de Ciències de l'Espai, Spain)

Time: June 7, 2011 (Tuesday) 10:30 AM

Location: middle conference room, 3rd floor

I would like to report on recent observations and archival data analysis on gamma-ray binaries. Time allowing, INTEGRAL, Swift, Chandra, and RXTE observations are presented and discussed. Particular attention will be put to discussing the variability of the X-ray emission at different timescales and the implications it might have in unveiling the nature of gamma-ray binaries in general, and of LS I 61 303 specifically. RXTE observations of LS I 61 303 cover now more than 50 contiguous cycles of the system orbital motion. Analyzing this X-ray monitoring data set, the largest to date for this source, I report on the variability of the orbital profile and the spectral distribution, and on newly discovered flares. I will make emphasis on a Swift–BAT detection of a 0.2 s short burst from the direction of LS I 61 303, which is resembling those often observed in Soft Gamma Repeaters (SGRs) and Anomalous X-ray Pulsars (AXPs), commonly labelled as magnetar-like short bursts. I will show that it is likely that the short burst was indeed originated in LS I +61 303, and thus, that this binary system is the first known hosting a magnetar, reinterpreting all observations from radio to TeV gamma-rays under this lore.