Unveiling the central engine of core-collapse supernovae in the Local Universe: NS or BH?

Abstract

The physical trigger powering supernovae following the core collapse of massive stars is believed to involve a neutron star (NS) or a black hole (BH), depending largely on progenitor mass. A potentially distinct signature is a long-duration gravitational wave (GW) burst from BH central engines by their ample energy reservoir $E_J$ in angular momentum, far more so than an NS can provide. A natural catalyst for this radiation is surrounding high-density matter in the form of a non-axisymmetric disk or torus. Here, we derive a detailed outlook on LVK probes of core-collapse supernovae CC-SNe during the present observational run O4 based on their event rate, an association with normal long GRBs and mass-scaling of GW170817B/GRB170817A. For BH central engines of mass $M$, GW170817B predicts a descending GW-chirp of energy ${\mathcal{E}}_{GW}\simeq 3.5\%M_{\odot }{c}^2\left(M/M_0\right)$ at frequency $f_{GW}\lesssim 700\mathrm{Hz}\left(M_0/M\right)$, where $M_0\simeq 2.8M_{\odot }$. For a few tens of events per year well into the Local Universe within 50-100Mpc, probes at the detector-limited sensitivity are expected to break the degeneracy between their NS or BH central engines {by GW calorimetry.

20 pages, 9 figures, to appear in ApJL