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

Free access article

Issue		A&A Volume 438, Number 2, August I 2005


Page(s)		545 - 556
Section		Galactic structure, stellar clusters and populations
DOI		http://dx.doi.org/10.1051/0004-6361:20042035

A&A 438, 545-556 (2005)
DOI: 10.1051/0004-6361:20042035

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

V. F. Cardone¹ and M. Sereno^{2, 3}

¹ Dipartimento di Fisica "E.R. Caianiello", Università di Salerno, and INFN, Sez. di Napoli, Gruppo Coll. di Salerno, via S. Allende, 84081 Baronissi (Salerno), Italy
e-mail: winny@na.infn.it
² Dipartimento di Scienze Fisiche, Università di Napoli, and INFN, Sez. di Napoli, Complesso Universitario di Monte S. Angelo, via Cinthia, 80126 Napoli, Italy
³ Istituto Nazionale di Astrofisica - Osservatorio Astronomico di Capodimonte, Salita Moiariello 16, 80131 Napoli, Italy

(Received 21 September 2004 / Accepted 19 January 2005 )

Abstract
We use the adiabatic compression theory to build a physically well-motivated Milky Way mass model in agreement 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, $M_{{\rm bulge}}$ , and the local disc surface density, $\Sigma_{\odot}$ . To model the dark matter component, we adiabatically compress a Navarro, Frenk and White (NFW) halo (with concentration c and total mass $M_{{\rm vir}}$ ) for fixed values of the spin parameter $\lambda$ , the fraction of the mass in baryons $m_{\rm b}$ , and the thin disc contribution to total angular momentum $j_{\rm d}$ . An iterative selection procedure is used to explore in detail the wide space of parameters only selecting those combinations of $\left\{ R_0, M_{{\rm bulge}}, \Sigma_{\odot}, \lambda, m_{\rm b}, j_{\rm d}, c, M_{{\rm vir}} \right\}$ 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, $0.8 \times 10^{10}~M_{\odot} < M_{{\rm bulge}} < 1.6 \times 10^{10}~M_{\odot}$ and $49~M_{\odot}~{\rm pc}^{-2} \le \Sigma_{\odot} \le 56~M_{\odot}~{\rm pc}^{-2}$ can be reconciled with the set of observational constraints. As regards the parameters entering the adiabatic compression, we find $0.03 \le \lambda \le 0.10$ and $0.04 \le m_{\rm b} \le 0.10$ , while final estimates of the parameters describing the initial halo profile turn out to be $5 \la c \la 12$ and $7 \times 10^{11}~M_{\odot} \la M_{{\rm vir}} \la 17 \times 10^{11}~M_{\odot}$ (all at 95.7% CL).

Key words: Galaxy: kinematics and dynamics -- Galaxy: structure -- galaxies: formation -- dark matter

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