Simulating Black Hole White Dwarf Encounters

TL;DR

This paper presents numerical simulations of white dwarf stars being disrupted by black holes, exploring the potential observational signatures of such events to identify intermediate mass black holes in stellar clusters.

Contribution

It introduces detailed numerical techniques to simulate the full disruption process of white dwarfs by black holes, including nuclear reactions and accretion disk formation.

Findings

Simulated white dwarf disruptions produce observable X-ray and nuclear signatures.

Disruption processes can lead to thermonuclear explosions detectable as underluminous supernovae.

Formation of accretion disks around black holes during disruption events was characterized.

Abstract

The existence of supermassive black holes lurking in the centers of galaxies and of stellar binary systems containing a black hole with a few solar masses has been established beyond reasonable doubt. The idea that black holes of intermediate masses ($\sim 1000$ \msun) may exist in globular star clusters has gained credence over recent years but no conclusive evidence has been established yet. An attractive feature of this hypothesis is the potential to not only disrupt solar-type stars but also compact white dwarf stars. In close encounters the white dwarfs can be sufficiently compressed to thermonuclearly explode. The detection of an underluminous thermonuclear explosion accompanied by a soft, transient X-ray signal would be compelling evidence for the presence of intermediate mass black holes in stellar clusters. In this paper we focus on the numerical techniques used to simulate the entire disruption process from the initial parabolic orbit, over the nuclear energy release during tidal compression, the subsequent ejection of freshly synthesized material and the formation process of an accretion disk around the black hole.