Towards an extension of the catalogue of particle-accelerating colliding-wind binaries

Particle-accelerating colliding-wind binaries (PACWBs) constitute a class of massive stars known to be able to accelerate charged particles up to relativistic velocities. The latter property is identified mainly through the detection of synchrotron radiation in the radio domain, and in a few cases thanks to the detection of non-thermal radiation in the high energy domain. The catalogue of PACWBs contains about 40 objects, covering a wide parameter space in terms of stellar wind and orbital parameters. So far, there is no evidence for a strict criterion to justify the occurrence of a particle acceleration process only in a small fraction of the colliding-wind binaries population, admitting the possibility that it might be a frequent property among massive stars. In this contribution, I address the issue of the frequency of particle accelerators among massive binaries, and I discuss observation strategies aiming at identifying new members of the catalogue.