Ensemble pulsational characteristics of eclipsing binaries containing $β$ Cep stars observed by the TESS mission

Abstract: Massive pulsators in eclipsing binaries provide precise, model-independent stellar parameters that, combined with asteroseismic constraints, provide powerful probes of interior properties and angular-momentum transport in massive stars. This study investigates the pulsational characteristics and their impact on the structure and evolution of $β$ Cep pulsators in eclipsing binaries. We analyse an ensemble of 65 $β$ Cep stars in eclipsing binaries, identify rotationally split modes where possible, and statistically investigate the dependence of pulsational properties on binary orbital parameters. We derive their interior properties using MESA model grids and associated StORM pulsation frequencies, together with an asteroseismic routine that tracks stellar age and rotation across the $β$ Cep instability region. Interior rotation rates are derived for 14 systems that exhibit rotational mode splitting. While differential rotation is tentatively inferred for HD 112485, the other systems, except CZ Vel, are consistent with quasi-rigid rotation. The seismic and evolutionary properties of HD 112485 and EK Cru are derived through detailed forward asteroseismic modelling. HD 112485 is one of the least evolved $β$ Cep stars asteroseismically modelled to date, with a core hydrogen mass fraction $X_{c}= 0.501_{-0.013}<sup>{+0.009}$. The two reproduced zonal modes in HD 112485 are the first radial-order dipole pressure mode and the second radial-order quadrupole gravity mode, while the zonal modes in EK Cru are the second-order quadrupole mixed mode and the third order dipole pressure mode. A multivariate regression shows a negative correlation of the pulsation amplitude with pulsation frequency, and no statistically significant relationship with the orbital period. In addition, no significant relationship is observed between the pulsation frequency and the orbital period in this sample.