Gravitational radiation from magnetically funnelled supernova fallback onto a magnetar

TL;DR

This paper predicts gravitational wave emission from protomagnetars with magnetically funneled fallback accretion, highlighting how magnetic confinement enhances signals and influences black hole formation timing.

Contribution

It introduces the concept that magnetic funnelling creates polar mountains, boosting gravitational wave signals and affecting the evolution of fallback protomagnetars.

Findings

Magnetic funnelling creates a magnetically confined polar mountain.

Polar mountains boost gravitational wave signals.

Magnetic burial delays black hole formation.

Abstract

Protomagnetars spun up to millisecond rotation periods by supernova fallback are predicted to radiate gravitational waves via hydrodynamic instabilities for ~ 10^2 s before possibly collapsing to form a black hole. It is shown that magnetic funnelling of the accretion flow (i) creates a magnetically confined polar mountain, which boosts the gravitational wave signal, and (ii) "buries" the magnetic dipole moment, delaying the propeller phase and assisting black hole formation.