Constraining white-dwarf kicks in globular clusters : IV. Retarding Core Collapse

TL;DR

This paper investigates how velocity kicks received by white dwarfs in globular clusters influence cluster dynamics, potentially delaying core collapse by redistributing energy within the cluster core.

Contribution

It introduces a Monte-Carlo simulation approach to model white dwarf kicks and their impact on globular cluster evolution, highlighting a new mechanism affecting core dynamics.

Findings

White dwarf kicks can inject energy into the cluster core.

White dwarfs tend to lose energy in the central regions.

Kicks may delay core collapse or enlarge cluster cores.

Abstract

Observations of white dwarfs in the globular clusters NGC 6397 and Omega Centauri indicate that these stars may get a velocity kick during their time as giants. If the mass loss while on the asymptotic giant branch is slightly asymmetric, the resulting white dwarf could be born with such a velocity kick. These energetic white dwarfs will impart their excess energy on other stars as they travel through the cluster. A Monte-Carlo simulation of the white-dwarfs kicks combined with estimate of the phase-space diffusion of the white dwarfs reveals that as the white dwarfs equilibrate, they lose most of their energy in the central region of the cluster. They could possibly augment the effect of binaries, delaying core collapse or increasing the size of globular cluster cores.