Mathijs Vanrespaille, Dario J. Fritzewski, Vincent Vanlaer, Conny Aerts

Asteroseismic observations of the interior rotation of main sequence stars have shown that angular momentum transport is much more efficient than expected. Which transport mechanisms are responsible for this is still unclear. Detections of radial differential rotation provide valuable constraints on these transport mechanisms. This has been detected in several massive main sequence $β$ Cep pulsators, even though fewer than ten $β$ Cep stars have been asteroseismically modelled in detail so far. We aim to expand the sample of asteroseismically forward modelled $β$ Cep pulsators to maximally exploit their potential to observationally constrain angular momentum transport mechanisms. To that end, we seek to constrain their rotation profiles. We searched for rotational splitting of non-radial modes in a large $β$ Cep sample with identified mode degrees. These were subjected to a novel forward modelling approach, which consistently accounts for second-order rotation effects using the state-of-the-art StORM oscillation code. We successfully modelled 36 $β$ Cep stars and constrained crucial parameters such as their initial mass, internal rotation frequency, convective core mass, and age. Like in intermediate-mass main sequence stars, the internal rotation rate globally decreases in $β$ Cep stars as they evolve along the main sequence. Radial differential rotation is constrained in 17 $β$ Cep stars. The rotation rate in at least 14 stars varies by more than 10%. Of these 14 stars, ten have their rotation rate decreasing from the core to the surface while it is the opposite in four of them. We affirm that radial differential rotation is common in $β$ Cep stars. Moreover, our constrained rotation profiles suggest that the typical $β$ Cep rotation profile may be non-monotonic.