Speaker
Description
Recent studies suggest that star-forming regions may act as sources of very-high-energy (TeV) cosmic rays, independent of supernova remnants. Colliding-wind binaries (CWBs), known for their strong X-ray and radio synchrotron emission, have emerged as promising candidates for accelerating these particles. Here, we employ high-resolution three-dimensional magnetohydrodynamic simulations combined with test-particle integration to examine how local plasma conditions influence particle acceleration in CWBs. Our results show that both the maximum particle energies and the spectral hardness depend strongly on shock magnetization and cooling efficiency. For moderate magnetization levels (> 1 G), CWBs are capable of accelerating hadronic particles to hundreds of TeV and even PeV energies, with more than 1% of particles reaching the very-high-energy regime. By correlating local acceleration rates with key plasma properties—such as magnetic field strength, current density, vorticity, and velocity divergence—we find that turbulence and magnetic field complexity are the dominant drivers of acceleration, while classical diffusive shock acceleration plays a secondary role. These findings indicate that turbulent, magnetically driven mechanisms are central to the production of relativistic particles in CWBs, offering important implications for future high-sensitivity γ-ray observations, such as those planned with LACT and CTAO.
