DOI

https://doi.org/10.48717/4vjh-1959

Project

EM173

Title

CEN 1a and 1b: The third case of a colliding-wind binary emitting gamma

Abstract

Shocks are one of the most efficient environments to accelerate particles to relativistic energies and display non-thermal emission up to very-high-energy gamma rays. The fact that most of the massive stars are part of binary or higher multiplicity systems, implies that there must be a population of colliding wind binaries (CWBs) that can have an impact on the very-high-energy Galactic emission. Only two CWBs are known to exhibit gamma-rays to date, with two other candidates recently discovered. CEN 1a and CEN 1b is a quadruple system likely composed of two CWBs. However, many questions remain open in this system. We are conducting a multiwavelength campaign on this system to unveil the nature of the non-thermal emission. EVN observations of the system would be key to unambiguously identify the nature of the radio emission on each component of the system. We request two 9-h epochs at two different frequencies each to disentangle the thermal and non-thermal emission of each component and its variability. CEN 1a and 1b can be the third CWB emitting and gamma-rays, and the first confirmed case of two CWBs within the same system.