An Analytical Model of Spiral Galaxies

摘要

We present a self-consistent analytical model of spiral galaxies embedded in dark matter halos that follows the standard adiabatic contraction picture (e.g., Fall & Efstathiou 1980, MNRAS, 193, 189) in a hierarchical uni-verse adapted to the concordant ACDM cosmology. We have considered four realistic bi-parametric density distributions for the host halo: a Navarro-Frenk-White's (NFW) profile; a Hernquist's model; a Burkert's model; and the Sersic's 3D formula for n = 6. We have estimated the baryonic disk-mass fractions, md, and mass-to-light ratios required by all these halo profiles in order to match the RVL observed scaling relations of present-day spirals. We can also provide an-alytical formulas for the calculation of the characteristic size (scale length) and maximum rotational velocity of disks for a broad range of masses (disk lumi-nosities). Models like this are useful, for instance, for generating systematically initial conditions in numerical studies of the evolution of galaxy aggregations, like groups or clusters, where the large samples of galaxies make impractical the adoption of global properties tailored to each object.