Gravitational wave frequencies and energies in hypernovae

Abstract

A torus develops a state of suspended accretion against a magnetic wall around a rapidly rotating black hole formed in core-collapse hypernovae. It hereby emits about 10% of the black hole spin-energy in gravitational radiation from a finite number of multipole mass moments. We quantify the relation between the frequency of quadrupole gravitational radiation and the energy output $E_w$ in torus winds by $f_{gw}\simeq 470{Hz}(E_w/4\times 10^{52}{erg})^{1/2}(7M_\odot/M)^{3/2}$, where $M$ denotes the mass of the black hole. We propose that $E_w$ irradiates the remnant stellar envelope from within. We identify $E_w$ with energies $\sim 10^{52}$ erg inferred from X-ray observations on matter injecta; and the poloidal curvature in the magnetic wall with the horizon opening angle in baryon poor outflows that power true GRB energies of $E_γ\simeq 3\times 10^{51}$ erg.