Dynamical Models for Disk Galaxies with Triaxial Halos

TL;DR

This paper develops self-consistent dynamical models of disk galaxies with triaxial, cuspy halos, demonstrating that halo shape changes can be made adiabatically while maintaining equilibrium, and tests the impact on galaxy rotation curves.

Contribution

It introduces a method to create equilibrium models of disk galaxies with triaxial halos by applying an energy-conserving acceleration, preserving the density profile during deformation.

Findings

Halo triaxiality can be modeled while maintaining equilibrium.

The models suggest halo shape influences galaxy rotation curves.

Application to galaxy F568-3 tests the impact of halo shape on observed dynamics.

Abstract

We construct self-consistent dynamical models for disk galaxies with triaxial, cuspy halos. We begin with an equilibrium, axisymmetric, disk-bulge-halo system and apply an artificial acceleration to the halo particles. By design, this acceleration conserves energy and thereby preserving the system's differential energy distribution even as its phase space distribution function is altered. The halo becomes triaxial but its spherically-averaged density profile remains largely unchanged. The final system is in equilibrium, to a very good approximation, so long as the halo's shape changes adiabatically. The disk and bulge are ``live'' while the halo is being deformed; they respond to the changing gravitational potential but also influence the deformation of the halo. We test the hypothesis that halo triaxiality can explain the rotation curves of low surface brightness galaxies by modelling the galaxy F568-3.