A centrally heated dark halo for our Galaxy

Understand

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.