Dark matter and stellar populations in the central region of early-type galaxies

This thesis work is aimed at the investigation of the dark matter (DM) amount and distribution in early-type galaxies (ETGs), in relation with the stellar properties, constrained by observations of the kinematic fields of galaxies. In particular, we focus on observations of the projected stellar velocity dispersion in the central region of ETGs. A robust determination of the DM amount and distribution is an open issue, which we explore from two complementary points of view. A top-down approach, with priority given to cosmology, based on the predictions of numerical cosmological simulations, and a bottom-up approach, with priority given to the galactic astrophysics. This is accomplished by using the original numerical code JASMINE (Jeans AxiSymmetric Models of galaxies IN Equilibrium), first developed by Posacki et al. 2013, to build dynamical models of ETGs, based on the solution of the Jeans equations. Our Jeans modelling produces axisymmetric (oblate) spheroids with anisotropic stellar orbits. In this thesis work, we focus on spherical isotropic galaxy models, composed of stars, DM and a central supermassive black hole (BH). The stellar component is modelled by a deprojected de Vaucouleurs or Jaffe density profile and satisfies the Faber-Jackson and size-luminosity Scaling Laws. The BH mass, M_BH, is related to the total stellar mass, M_star, by the Magorrian relation. The DM component is modelled by the NFW density profile. We explore the effect on the dynamics of stars, due to the stellar and DM properties, such as the assumption of a fixed stellar mass-to-light ratio, Upsilon_star,dyn, and fixed halo parameters beta and c (halo-to-stellar scale radius ratio and halo concentration, respectively). We intend to investigate how much the DM amount and distribution can vary, while reproducing a given value for the projected central velocity dispersion of stars, sigma_e8 (luminosity-weighted within R_e/8). Our study suggests that sigma_e8 is not a good [...]