Stochastic Core Spin-Up in Massive Stars -- Implications of 3D Simulations of Oxygen Shell Burning

Understand

It has been suggested based on analytic theory that even in non-rotating supernova progenitors stochastic spin-up by internal gravity waves (IGWs) during the late burning stages can impart enough angular momentum to the core to result in neutron star birth spin periods below 100ms, and a relatively firm upper limit of 500ms for the spin period.

• We here investigate this process using a 3D simulation of oxygen shell burning in a $3M_\odot$ He star.
• Our model indicates that stochastic spin-up by IGWs is less efficient than previously thought.
• We find that the stochastic angular momentum flux carried by waves excited at the shell boundary is significantly smaller for a given convective luminosity and turnover time than would be expected from simple dimensional analysis.