Collapsars in Three Dimensions

TL;DR

This paper presents 3D simulations of massive, rotating Population III stars collapsing into black holes, revealing complex instabilities, hypernova explosions, and implications for gamma-ray bursts, nucleosynthesis, and gravitational waves.

Contribution

First 3D simulation of a realistic collapsar progenitor showing non-axisymmetric instabilities and their effects on outflows and explosions.

Findings

Formation of spiral structures due to instabilities in high angular momentum cases

Development of hypernova explosions with energies around 1e52 erg

Absence of relativistic jets without magnetic fields

Abstract

We present the results of 3-dimensional simulations of the direct collapse to a black hole of a rotating, 60-solar-mass, zero metallicity, population III star. Because the structure of this star (angular momentum, density and temperature profiles) is similar to many collapsar gamma-ray burst progenitors, these calculations have implications beyond the fate of population III stars. These simulations provide a first 3-dimensional look at a realistic collapsar progenitor, and the results are very different from any previous 2-dimensional calculations. If the angular momentum of the progenitor is high, non-axisymmetric instabilities in the collapsing core cause spiral structures to form, and these structures shape later outflows. These outflows are driven by the imbalance between viscous heating and inefficient neutrino cooling and ultimately develop into a 1e52 erg explosion. Without magnetic fields, this collapse will not produce relativistic jets, but the explosion is indeed a hypernova. We conclude with a discussion of the implications of such calculations on the explosions, nucleosynthesis, neutrino flux and gravitational wave emission from the collapse of massive stars.