Unveiling the Central Engine of Core-collapse Supernovae in the Local Universe: Neutron Star or Black Hole?

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 long-duration gravitational-wave (GW) bursts 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 nonaxisymmetric disk or torus. Here, we derive a detailed prospect on LIGO–Virgo–KAGRA probes of core-collapse supernovae during the present observational run O4 based on their event rate, an association with normal long gamma-ray bursts (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 ≃ 2.8 M _⊙ . For a few tens of events per year well into the Local Universe within 50–100 Mpc, probes at the detector-limited sensitivity are expected to break the degeneracy between their NS or BH central engines by GW calorimetry.

Keywords

• Supernova dynamics