Black-Hole Formation Accompanied by the Supernova Explosion of a 40-M$_{\odot}$ Progenitor Star

Adam Burrows, David Vartanyan, Tianshu Wang

Published 2023-08-10Version 1

We have simulated the collapse and evolution of the core of a solar-metallicity 40-M$_{\odot}$ star and find that it explodes vigorously by the neutrino mechanism. This despite its very high ``compactness". Within $\sim$1.5 seconds of explosion, a black hole forms. The explosion is very asymmetrical and has a total explosion energy of $\sim$1.6$\times$10$^{51}$ ergs. At black hole formation, its baryon mass is $\sim$2.434 M$_{\odot}$ and gravitational mass is 2.286 M$_{\odot}$. Seven seconds after black hole formation an additional $\sim$0.2 M$_{\odot}$ is accreted, leaving a black hole baryon mass of $\sim$2.63 M$_{\odot}$. A disk forms around the proto-neutron star, from which a pair of neutrino-driven jets emanates. These jets accelerate some of the matter up to speeds of $\sim$45,000 km s$^{-1}$ and contain matter with entropies of $\sim$50. The large spatial asymmetry in the explosion results in a residual black hole recoil speed of $\sim$1000 km s$^{-1}$. This novel black-hole formation channel now joins the other black-hole formation channel between $\sim$12 and $\sim$15 M$_{\odot}$ discovered previously and implies that the black-hole/neutron-star birth ratio for solar-metallicity stars could be $\sim$20%. However, one channel leaves black holes in perhaps the $\sim$5-15 M$_{\odot}$ range with low kick speeds, while the other leaves black holes in $\sim$2.5 M$_{\odot}$ mass range with high kick speeds. This exotic channel of lower-mass black hole formation, accompanied by a very asymmetrical supernova explosion, reveals the importance of performing detailed and fully 3D simulations in order to determine the mapping of initial states to outcomes in the core-collapse context.