# Testing lowered isothermal models with direct N-body simulations of globular clusters - II: Multimass models

## TL;DR

This study evaluates the effectiveness of multimass isothermal models in replicating the phase space properties of globular clusters as simulated by direct N-body methods, across various evolutionary stages and remnant retention scenarios.

## Contribution

It demonstrates that multimass models accurately reproduce density and velocity profiles of star clusters in different evolutionary phases and provides insights into the evolution of global parameters and observable features.

## Key findings

- Multimass models successfully match N-body simulation profiles.
- Radial anisotropy develops from low- to high-mass components over time.
- Velocity scale depends on mass as m^{-0.5}, with variations influenced by dark remnants.

## Abstract

Lowered isothermal models, such as the multimass Michie-King models, have been successful in describing observational data of globular clusters. In this study we assess whether such models are able to describe the phase space properties of evolutionary $N$-body models. We compare the multimass models as implemented in (Gieles \& Zocchi) to $N$-body models of star clusters with different retention fractions for the black holes and neutron stars evolving in a tidal field. We find that multimass models successfully reproduce the density and velocity dispersion profiles of the different mass components in all evolutionary phases and for different remnants retention. We further use these results to study the evolution of global model parameters. We find that over the lifetime of clusters, radial anisotropy gradually evolves from the low-mass to the high-mass components and we identify features in the properties of observable stars that are indicative of the presence of stellar-mass black holes. We find that the model velocity scale depends on mass as $m^{-\delta}$, with $\delta\simeq0.5$ for almost all models, but the dependence of central velocity dispersion on $m$ can be shallower, depending on the dark remnant content, and agrees well with that of the $N$-body models. The reported model parameters, and correlations amongst them, can be used as theoretical priors when fitting these types of mass models to observational data.