Supplying angular momentum to the jittering jets explosion mechanism using inner convection layers

Abstract

ABSTRACT We conduct one-dimensional stellar evolution simulations in the mass range 13–20 M⊙ to late core collapse times and find that an inner vigorous convective zone with large specific angular momentum fluctuations appears at the edge of the iron core during the collapse. The compression of this zone during the collapse increases the luminosity there and the convective velocities, such that the specific angular momentum fluctuations are of the order of $j_{\rm conv} \simeq 5 \times 10^{15} {~\rm cm}^2 {~\rm s}^{-1}$. If we consider that three-dimensional simulations show convective velocities that are three to four times larger than what the mixing length theory gives, and that the spiral standing accretion shock instability in the post-shock region of the stalled shock at a radius of ${\simeq}100 {~\rm km}$ amplifies perturbations, we conclude that the fluctuations that develop during core collapse are likely to lead to stochastic (intermittent) accretion discs around the newly born neutron star. In reaching this conclusion, we also make two basic assumptions with uncertainties that we discuss. Such intermittent discs can launch jets that explode the star in the frame of the jittering jets explosion mechanism.