Abstract
Abstract We investigate axisymmetric black hole (BH) formation and its gravitational wave (GW) and neutrino signals with self-consistent core-collapse supernova simulations of a non-rotating 40 M ⊙ progenitor star using the isotropic diffusion source approximation for the neutrino transport and a modified gravitational potential for general relativistic effects. We consider four different neutron star (NS) equations of state (EoS): LS220, SFHo, BHBΛϕ, and DD2, and study the impact of the EoS on BH formation dynamics and GW emission. We find that the BH formation time is sensitive to the EoS from 460 to >1300 ms and is delayed in multiple dimensions for ∼100–250 ms due to the finite entropy effects. Depending on the EoS, our simulations show the possibility that shock revival can occur along with the collapse of the proto-neutron star (PNS) to a BH. The gravitational waveforms contain four major features that are similar to previous studies but show extreme values: (1) a low-frequency signal (∼300–500 Hz) from core-bounce and prompt convection, (2) a strong signal from the PNS g-mode oscillation among other features, (3) a high-frequency signal from the PNS inner-core convection, and (4) signals from the standing accretion shock instability and convection. The peak frequency at the onset of BH formation reaches to ∼2.3 kHz. The characteristic amplitude of a 10 kpc object at peak frequency is detectable but close to the noise threshold of the Advanced LIGO and KAGRA, suggesting that the next-generation GW detector will need to improve the sensitivity at the kHz domain to better observe stellar-mass BH formation from core-collapse supernovae or failed supernovae.
Highlights
Supernovae are the spectacular birth places of neutron stars (NSs) and stellar-mass black holes (BHs) in the universe
We investigate axisymmetric black hole (BH) formation and its gravitational wave (GW) and neutrino signals with self-consistent core-collapse supernova simulations of a non-rotating 40 M⊙ progenitor star using the isotropic diffusion source approximation for the neutrino transport and a modified gravitational potential for general relativistic effects
We find that the BH formation time is sensitive to the equations of state (EoS) from 460 to > 1300 ms and is delayed in multiple dimensions for ∼ 100 − 250 ms due to the finite entropy effects
Summary
Supernovae are the spectacular birth places of neutron stars (NSs) and stellar-mass black holes (BHs) in the universe. There is no firm conclusion on the explodability of core-collapse SN from first principle calculations, one-dimensional (1D) spherical symmetry simulations of failed SN and BH formation have been investigated by Liebendorfer et al (2004); O’Connor & Ott (2011); Sumiyoshi et al (2007); Ugliano et al (2012); Char et al (2015); Sukhbold et al (2016). These studies suggest that the mass range of SN progenitors that may end up with a BH is not monotonic in mass, and the BH formation time is sensitive to the progenitor density structure (or the so-called compactness parameter introduced in O’Connor & Ott 2011) and the nuclear equation of state (EoS) used. Spherically symmetric simulations cannot accurately account for multidimensional effects such as turbulence, convection, and rotation, which are considered crucial ingredients for achieving successful explosions
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