A centrally heated dark halo for our Galaxy

TL;DR

This paper develops a new analytic model of the Milky Way's dark matter halo, incorporating self-consistent potentials and fitting multiple observational constraints, revealing a core-like halo structure with nearly constant phase-space density.

Contribution

It introduces a novel family of galaxy models with analytic distribution functions for dark matter and stars, fitted to observational data including rotation curves and stellar kinematics.

Findings

Dark halo has a roughly constant phase-space density for |J| 140 kpc km^-1

Halo exhibits a core radius of approximately 2 kpc

Model successfully matches various observational constraints

Abstract

We construct a new family of models of our Galaxy in which dark matter and disc stars are both represented by distribution functions that are analytic functions of the action integrals of motion. The potential that is self-consistently generated by the dark matter, stars and gas is determined, and parameters in the distribution functions are adjusted until the model is compatible with observational constraints on the circular-speed curve, the vertical density profile of the stellar disc near the Sun, the kinematics of nearly 200 000 giant stars within 2 kpc of the Sun, and estimates of the optical depth to microlensing of bulge stars. We find that the data require a dark halo in which the phase-space density is approximately constant for actions |J| \lesssim 140 kpc km ^-1. In real space these haloes have core radii ~ 2 kpc.