出版社：SISSA, Scuola Internazionale Superiore di Studi Avanzati
摘要：High-resolution radio observations have revealed that non-thermal radio emission in Wolf-Rayet
(WR) stars arises where the stellar wind of the WR star collides with that of a binary companion.
These colliding-wind binary (CWB) systems offer an important laboratory for investigating the
underlying physics of particle acceleration. Hydrodynamic models of the binary stellar winds and
the wind-collision region (WCR) that account for the evolution of the electron energy spectrum,
largely due to inverse Compton cooling, are now available. Radiometry and imaging obtained
with the VLA, MERLIN, EVN and VLBA provide essential constraints to these models. Models
of the radio emission from WR146 and WR147 are shown, though these very wide systems do
not have defined orbits and hence lack a number of important model parameters. Multi-epoch
VLBI imaging of the archetype WR+O star binary WR140 through a part of its 7.9-year orbit
has been used to define the orbit inclination, distance and the luminosity of the companion star to
enable the best constraints for any radio emitting CWB system. Models of the spatial distribution
of relativistic electrons and ions, and the magnetic energy density are used to model the radio
emission, and also to predict the high energy emission at X-ray and g -ray energies. It is clear
that high-energy facilities e.g. GLAST and VERITAS, will be important for constraining particle
acceleration parameters such as the spectral index of the energy spectrum and the acceleration
efficiency of both ions and electrons, and in turn, identify unique models for the radio spectra.
This will be especially important in future attempts to model the spectra of WR140 throughout
its complete orbit. A WCR origin for the synchrotron emission in O-type stars, the progenitors of
WR stars, is illustrated by observations of Cyg OB2 #9.
