Open AccessINTEGRAL and XMM–Newton observations of LSI +61° 303
Author(s) -
Chernyakova M.,
Neronov A.,
Walter R.
Publication year - 2006
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1111/j.1365-2966.2006.10946.x
Subject(s) - physics , astronomy , astrophysics
LSI +61° 303 is one of the few X‐ray binaries with Be star companion from which both radio and high‐energy γ‐ray emission have been observed. We present XMM–Newton and INTEGRAL observations which reveal variability of the X‐ray spectral index of the system. The X‐ray spectrum is hard (photon index Γ≃ 1.5 ) during the orbital phases of both high and low X‐ray flux. However, the spectrum softens at the moment of transition from high to low X‐ray state. The spectrum of the system in the hard X‐ray band does not reveal the presence of a cut‐off (or, at least a spectral break) at 10–60 keV energies, expected if the compact object is an accreting neutron star. The observed spectrum and spectral variability can be explained if the compact object in the system is a rotation‐powered pulsar.