A systematic analysis of star cluster disruption by tidal shocks -- II. Predicting star cluster dissolution rates from a time-series analysis of their tidal histories

TL;DR

This study demonstrates that star cluster dissolution rates can be statistically predicted from their tidal histories using a large suite of N-body simulations, revealing how tidal shock properties influence cluster longevity.

Contribution

It introduces a method to predict star cluster disruption by analyzing the statistical properties of their tidal histories through time-series analysis, simplifying population evolution modeling.

Findings

Dissolution timescales are nearly independent of the power spectrum slope at fixed normalisation.

Dispersion in dissolution times increases with the power spectrum slope.

Clusters with high-frequency shocks have more similar mass loss histories.

Abstract

Most of the dynamical mass loss from star clusters is thought to be caused by the time-variability of the tidal field (``tidal shocks''). Systematic studies of tidal shocks have been hampered by the fact that each tidal history is unique, implying both a reproducibility and a generalisation problem. Here we address these issues by investigating how star cluster evolution depends on the statistical properties of its tidal history. We run a large suite of direct N-body simulations of clusters with tidal histories generated from power spectra of a given slope and with different normalisations, which determine the time-scales and amplitudes of the shocks, respectively. At fixed normalisation (i.e. the same median tidal field strength), the dissolution time-scale is nearly independent of the power spectrum slope. However, the dispersion in dissolution time-scales, obtained by repeating simulations for different realisations of statistically identical tidal histories, increases with the power spectrum slope. This result means that clusters experiencing high-frequency shocks have more similar mass loss histories than clusters experiencing low-frequency shocks. The density-mass relationship of the simulated clusters follows a power-law with slope between 1.08 and 1.45, except for the lowest normalisations (for which clusters effectively evolve in a static tidal field). Our findings suggest that star cluster evolution can be described statistically from a time-series analysis of its tidal history, which is an important simplification for describing the evolution of the star cluster population during galaxy formation and evolution.