New tools for probing the phase space structure of dark matter halos

TL;DR

This paper discusses spectral methods for analyzing the phase space of dark matter halos in simulations, revealing how baryonic growth influences halo shape and orbit behavior.

Contribution

It introduces spectral analysis techniques to study orbit structures in dark matter halos and explains the impact of baryonic growth on halo shape evolution.

Findings

Halo shape changes are driven by adiabatic orbit shape changes due to baryonic growth.

Chaotic orbit scattering occurs mainly with very compact central masses.

Orbit shape evolution varies with radius and orbit type.

Abstract

We summarize recent developments in the use of spectral methods for analyzing large numbers of orbits in N-body simulations to obtain insights into the global phase space structure of dark matter halos. The fundamental frequencies of oscillation of orbits can be used to understand the physical mechanism by which the shapes of dark matter halos evolve in response to the growth of central baryonic components. Halos change shape primarily because individual orbits change their shapes adiabatically in response to the growth of a baryonic component, with those at small radii become preferentially rounder. Chaotic scattering of orbits occurs only when the central point mass is very compact and is equally effective for centrophobic long-axis tube orbits as it is for centrophilic box orbits.