Angular Momentum in Dwarf Galaxies

2014

Abstract. We study the "angular momentum catastrophe" in the framework of interaction among baryons and dark matter through dynamical friction. By means of Del Popolo (2009) model we simulate 14 galaxies similar to those investigated by van den Bosch, Burkert and Swaters (2001), and calculate the distribution of their spin parameters and the angular momenta. Our model gives the angular momentum distribution which is in agreement with the van den Bosch et al. observations. Our result shows that the "angular momentum catastrophe" can be naturally solved in a model that takes into account the baryonic physics and the exchange of energy and angular momentum between the baryonic clumps and dark matter through dynamical friction.

Angular Momentum in Dwarf Galaxies

2014

Improvements in the Spherical Collapse Model and Dark Energy Cosmologies

2014

Abstract. In the present paper, we study how the effects of deviations from spherical symmetry of a system, produced by angular momentum, and shear stress, influence typical parameters of the spherical collapse model, like the linear density threshold for collapse of the non-relativistic component (δ c ) and its virial overdensity (∆ V ). The study is performed in the framework of the Einstein-de Sitter and ΛCDM models, and assuming that the vacuum component is not clustering within the homogeneous non-spherical overdensities. We start from the standard spherical top hat model (SCM) which does not take account the non-spherical effects, and we add to this model the shear term and angular momentum term, which are finally expressed in terms of the density contrast, δ. We find that the non-spherical terms change the non-linear evolution of the system and that the collapse stops "naturally" at the virial radius, differently from the standard spherical collapse model. Moreover, shear and rotation gives rise to higher values of the linear overdensity parameter and different values of ∆ V with respect to the standard spherical collapse model.

On the Pseudo Phase-space Density of Dark Matter Haloes and the Universality of Density Profiles

2015