Calibrating angular momentum transport in intermediate-mass stars from gravity-mode asteroseismology

Context. The asteroseismology of gravity-mode ( g -mode) pulsators covering BAF-type stars has shown that angular momentum is redistributed during the main sequence. The efficiency of the transport, however, remains largely uncalibrated. Aims. This aim of this paper is to exploit a sample of 2937 characterised g -mode pulsators (the largest sample to date) to place constraints on the efficiency of angular momentum transport by assuming an effective viscosity or an Eddy viscosity based on the Tayler–Spruit dynamo within a fully diffusive framework. Methods. We computed grids of rotating stellar evolution models that we then used to simulate a population of stars by sampling from these grids with prior distributions on the mass, age, and initial rotation rate. We then compared these simulated distributions of rotation frequencies and specific angular momentum ( J / M ) to those of the sample of observed stars. Results. We find that a fully diffusive framework for the transport of angular momentum during the main sequence is sufficient to explain the observed evolution of near-core rotation frequencies, the observed differential rotation, and the observed mass dependence of J / M when the effective viscosity (assumed constant) is 10 6 cm 2 s −1 or higher. Viscosities predicted by the Tayler–Spruit dynamo are in general far above this value and can explain the data as well. Conclusions. Future observational studies of main sequence g -mode pulsators are encouraged to measure core-to-surface rotation rates, particularly of B-type stars. For this work we have exploited the constraining potential of near-core rotation frequencies alone, while the contrast with the surface rotation would allow us to further unravel the mechanisms driving the transport.