A. Szostek, G. Dubus, M. V. McSwain
Gamma-ray binaries emit most of their radiated power beyond ~10 MeV. The
non-thermal emission is thought to arise from the interaction of the
relativistic wind of a rotation-powered pulsar with the stellar wind of its
massive (O or Be) companion star. A powerful pulsar creates an extended cavity,
filled with relativistic electrons, in the radiatively-driven wind of the
massive star. As a result, the observed P Cyg profiles of UV resonant lines
from the stellar wind should be different from those of single massive stars.
We propose to use UV emission lines to detect and constrain the colliding wind
region in gamma-ray binaries. We compute the expected orbital variability of P
Cyg profiles depending upon the interaction geometry (set by the ratio of
momentum fluxes from the winds) and the line-of-sight to the system. We predict
little or no variability for the case of LS 5039 and PSR B1259-63, in agreement
with currently available HST observations of LS 5039. However, variability
between superior and inferior conjunction is expected in the case of LS I+61
303.
View original:
http://arxiv.org/abs/1111.6975
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