Stars Bisected by Relativistic Blades

Abstract

We consider the dynamics of an equatorial explosion powered by a millisecond magnetar formed from the core collapse of a massive star. We study whether these outflows—generated by a priori magneto-centrifugally driven, relativistic magnetar winds—might be powerful enough to produce an ultrarelativistic blade (“lamina”) that successfully carves its way through the dense stellar interior. We present high-resolution numerical special-relativistic hydrodynamic simulations of axisymmetric centrifugally driven explosions inside a star and follow the blast wave propagation just after breakout. We estimate the engine requirements to produce ultrarelativistic lamina jets and comment on the physicality of the parameters considered. We find that sufficiently collimated—half-opening angle θ _r ≤ 0.°2—laminas successfully break out of a compact progenitor at ultrarelativistic velocities ( ${{\rm{\Gamma }}}_{\mathrm{core}}\gtrsim 30$ ) and extreme isotropic energies ( E _k _,iso ∼ 5 × 10 ^52 erg) within a few percent of the typical spin-down period for a millisecond magnetar. The various phases of these ultrathin outflows, such as collimation shocks, Kelvin–Helmholtz instabilities, and lifetime, are discussed, and we speculate on the observational signatures echoed by this outflow geometry.

Keywords

• Relativistic jets
• Magnetars
• Relativistic fluid dynamics