Action-based distribution functions for spheroidal galaxy components

TL;DR

This paper introduces a method for constructing distribution functions based on action integrals, enabling the creation of self-consistent models of spheroidal galaxy components for better understanding and simulation of galactic dynamics.

Contribution

The paper presents a novel approach to designing action-based distribution functions that can generate various stellar systems and be combined for multi-component galaxy models.

Findings

Derived distribution functions for Hernquist, Jaffe, and NFW models.

Models are self-consistent and extendable to flattened and rotating systems.

Facilitates interpretation of observational data and galaxy simulations.

Abstract

We present an approach to the design of distribution functions that depend on the phase-space coordinates through the action integrals. The approach makes it easy to construct a dynamical model of a given stellar component. We illustrate the approach by deriving distribution functions that self-consistently generate several popular stellar systems, including the Hernquist, Jaffe, and Navarro, Frenk and White models. We focus on non-rotating spherical systems, but extension to flattened and rotating systems is trivial. Our distribution functions are easily added to each other and to previously published distribution functions for discs to create self-consistent multi-component galaxies. The models this approach makes possible should prove valuable both for the interpretation of observational data and for exploring the non-equilibrium dynamics of galaxies via N-body simulation.