Black hole to breakout: 3D GRMHD simulations of collapsar jets reveal a wide range of transients

TL;DR

This study uses pioneering 3D GRMHD simulations to explore how different progenitor star structures influence collapsar jet formation, outflow types, and observable gamma-ray burst characteristics.

Contribution

First 3D GRMHD simulations of collapsars connecting jet launching to breakout, revealing diverse outflow types and their dependence on progenitor properties.

Findings

Identified three outflow types: subrelativistic, SASI, and relativistic jets.

Jets can suppress accretion rates and have breakout times influenced by stellar magnetization.

Progenitors with steep density profiles face challenges as GRB progenitors due to luminosity and lightcurve issues.

Abstract

We present a suite of the first 3D GRMHD collapsar simulations, which extend from the self-consistent jet launching by an accreting Kerr black hole (BH) to the breakout from the star. We identify three types of outflows, depending on the angular momentum, $ l $, of the collapsing material and the magnetic field, $ B $, on the BH horizon: (i) Subrelativistic outflow (low $ l $ and high $ B $), (ii) Stationary accretion shock instability (SASI; high $ l $ and low $ B $), (iii) Relativistic jets (high $ l $ and high $ B $). In the absence of jets, free-fall of the stellar envelope provides a good estimate for the BH accretion rate. Jets can substantially suppress the accretion rate, and their duration can be limited by the magnetization profile in the star. We find that progenitors with large (steep) inner density power-law indices ($ \gtrsim 2 $), face extreme challenges as gamma-ray burst (GRB) progenitors due to excessive luminosity, global time evolution in the lightcurve throughout the burst and short breakout times, inconsistent with observations. Our results suggest that the wide variety of observed explosion appearances (supernova/supernova+GRB/low-luminosity GRBs) and the characteristics of the emitting relativistic outflows (luminosity and duration) can be naturally explained by the differences in the progenitor structure. Our simulations reveal several important jet features: (i) strong magnetic dissipation inside the star, resulting in weakly magnetized jets by breakout that may have significant photospheric emission and (ii) spontaneous emergence of tilted accretion disk-jet flows, even in the absence of any tilt in the progenitor.