# The Cusp-Core problem and the Secondary Infall Model - Astrophysics > Cosmology and Nongalactic Astrophysics

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Abstract: We study the cusp-core problem using a secondary infall model SIM thattakes into account the effect of ordered and random angular momentum, dynamicalfriction and baryons adiabatic contraction. The model is applied to structureson galactic scales normal and dwarfs spiral galaxies and on clusters ofgalaxies scales. Our analysis suggest that angular momentum and dynamicalfriction are able, on galactic scales, to overcome the competing effect ofadiabatic contraction eliminating the cusp. The slope of density profile ofinner haloes flattens with decreasing halo mass and the profile is wellapproximated by a Burkert-s profile. In order to obtain the NFW profile,starting from the profiles obtained from our model, the magnitude of angularmomentum and dynamical friction must be reduced with respect to the valuespredicted by the model itself. The rotation curves of four LSB galaxies fromGentile et al. 2004 are compared to the rotation curves obtained by the modelin the present paper obtaining a good fit to the observational data. The timeevolution of the density profile of a galaxy of $10^8-10^9 M {\odot}$ showsthat after a transient steepening, due to the adiabatic contraction, thedensity profile flattens to $\alpha \simeq 0$. On cluster scales we observe asimilar evolution of the dark matter density profile but in this case thedensity profile slope flattens to $\alpha \simeq 0.6$ for a cluster of $\simeq10^{14} M {\odot}$. The total mass profile, differently from that of darkmatter, shows a central cusp well fitted by a NFW model.

Autor: A. Del Popolo 1 Dipartimento di Fisica e Astronomia, Universitá di Catania, Catania, Italy; 2 Argelander-Institut für Astronomi

Fuente: https://arxiv.org/