# Protomagnetar and black hole formation in high-mass stars

## TL;DR

This study uses advanced simulations to explore how high-mass stars can evolve into protomagnetars or black holes, highlighting the influence of stellar structure and angular momentum on their fate.

## Contribution

It introduces detailed axisymmetric simulations coupling relativistic MHD, gravity, and neutrino transport to analyze stellar core collapse outcomes.

## Key findings

- Black holes can form after long post-collapse phases in high-mass stars.
- Protomagnetars result from cores with standard angular momentum profiles.
- Collapse paths depend on progenitor structure and angular momentum distribution.

## Abstract

Using axisymmetric simulations coupling special relativistic MHD, an approximate post-Newtonian gravitational potential and two-moment neutrino transport, we show different paths for the formation of either protomagnetars or stellar mass black holes. The fraction of prototypical stellar cores which should result in collapsars depends on a combination of several factors, among which the structure of the progenitor star and the profile of specific angular momentum are probably the foremost. Along with the implosion of the stellar core, we also obtain supernova-like explosions driven by neutrino heating and hydrodynamic instabilities or by magneto-rotational effects in cores of high-mass stars. In the latter case, highly collimated, mildly relativistic outflows are generated. We find that after a rather long post-collapse phase (lasting >~ 1 sec) black holes may form in cases both of successful and failed supernovalike explosions. A basic trend is that cores with a specific angular momentum smaller than that obtained by standard, one-dimensional stellar evolution calculations form black holes (and eventually collapsars). Complementary, protomagnetars result from stellar cores with the standard distribution of specific angular momentum obtained from prototypical stellar evolution calculations including magnetic torques and moderate to large mass loss rates.