Is there a neutron star in the gamma-ray binary LS I +61 303 ?

ORELLANA, M.; ROMERO, G.E.

Cairo y Alexandria, Egipto

Congreso; Neutron Stars & Gamma Ray Bursts: Recent Developments and Future Directions; 2009

Egyptian Academy of Science, US-Egypt Science & Technology Cooperation

LS I +61 303 is a binary system that displays periodic variability along the orbit throughout all the electromagnetic spectrum, up to the TeV-energy domain. Despite many observational efforts the identification of the compact component of the system remains inconclusive.Two main models for the radio and high-energy emission have been developed. One of these models proposes that this system might contain a non-accreting pulsar in orbit around a Be-star. In such a case, the reported changes of the radio morphology are interpreted as due to the interaction of the relativistic wind from a young pulsar with the wind from the early-type star. The other model (or family of models) invokes accretion/ejection of matter from the compact object, that might be either a low magnetic field pulsar or a black hole.A recent X-ray monitoring campaign performed by RXTE has detected large flaring episodes and the fastest variability ever observed from LSI +61 303, which thus places constraints on the size of the X-ray emitting region. We discuss here the implications for mentioned scenarios.