Modelling the Milky Way through adiabatic compression of cold dark matter haloes

Abstract

We use the adiabatic compression theory to build a physically well-motivated Milky Way mass model in agree- ment with observational data. The visible mass of the Galaxy is distributed in a spheroidal bulge and a multi-component disc parametrized by three galactic parameters, the Sun distance to the galactic centre, R0, the total bulge mass, Mbulge ,a nd the local disc surface density, Σ� . To model the dark matter component, we adiabatically compress a Navarro, Frenk and White (NFW) halo (with concentration c and total mass Mvir) for fixed values of the spin parameter λ, the fraction of the mass in baryons mb, and the thin disc contribution to total angular momentum jd. An iterative selection procedure is used to explore in detail the wide space of parameters only selecting those combinations of R0, Mbulge, Σ� ,λ ,mb, jd, c, Mvir that give rise to a Milky Way model in agreement with observational constraints. This analysis leads us to conclude that only models with R0 = 8.5 kpc, 0.8 × 10 10 M� < Mbulge < 1.6 × 10 10 Mand 49 Mpc −2 ≤ Σ� ≤ 56 Mpc −2 can be reconciled with the set of observational constraints. As regards the parameters entering the adiabatic compression, we find 0.03 ≤ λ ≤ 0.10 and 0.04 ≤ mb ≤ 0.10, while final estimates of the parameters describing the initial halo profile turn out to be 5 < c < 12 and 7 × 10 11 M� < Mvir < 17 × 10 11 M� (all at 95.7% CL).