Probing Dynamical Dark Energy with Press-Schechter Mass Functions

Measurement of accelerated expansion in the Universe led to propose a new cosmic fluid as its cause: dark energy. Its various incarnations offer a wealth of models whose relevance it is important to discriminate via contacts with observations. I will present my investigations on the influence of dynamical dark energy models on the formation of non-linear dark matter structures. In particular, I will focus on structures traced by the mass function of dark matter haloes.Comment: submitted to the Proceedings of the 11th Marcel Grossmann Meeting, MG11, Berlin, Germany, July 23-29, 2006 (2007) to be publishe

A unified solution to the small scale problems of the Λ\LambdaCDM model II: introducing parent-satellite interaction

We continue the study of the impact of baryon physics on the small scale problems of the $\Lambda$CDM model, based on a semi-analytical model (Del Popolo, 2009). Withsuch model, we show how the cusp/core, missing satellite (MSP), Too Big to Fail (TBTF) problems and the angular momentum catastrophe can be reconciled with observations, adding parent-satellite interaction. Such interaction between darkmatter (DM) and baryons through dynamical friction (DF) can sufficiently flattenthe inner cusp of the density profiles to solve the cusp/core problem. Combining, in our model, a Zolotov et al. (2012)-like correction, similarly to Brooks et al. (2013), and effects of UV heating and tidal stripping, the number of massive, luminous satellites, as seen in the Via Lactea 2 (VL2) subhaloes,is in agreement with the numbers observed in the MW, thus resolving the MSP and TBTF problems. The model also produces a distribution of the angular spin parameter and angular momentum in agreement with observations of the dwarfs studied by van den Bosch, Burkert, \\& Swaters (2001).Comment: 24pp, 5figs. arXiv admin note: text overlap with arXiv:1404.367

Separating expansion from contraction and generalizing TOV condition in spherically symmetric models with pressure

We investigate spherically symmetric solutions with pressure and discuss the existence of a dividing shell separating expanding and collapsing regions. We perform a 3+1 splitting and obtain gauge invariant conditions relating not only the intrinsic spatial curvature of the shells to the ADM mass, but also a function of the pressure which we introduce that generalises the Tolman-Oppenheimer-Volkoff equilibrium condition. We consider the particular case of a Lema\^itre-Tolman dust models with a cosmological constant (a $\Lambda$-CDM model) as an example of our results.Comment: 4pp, 1fig, AIP Conference: Proc. XXXI Spanish Relat. Meeting, ERE08, Salamanca, Spain, 15-19 Sept., 2008 Septembre, Salamanca, Espagn

Dark Energy-Dark Matter Interaction from the Abell Cluster A586

We find that deviation from the virial equilibrium of the Abell Cluster A586 yields evidence of the interaction between dark matter and dark energy. We argue that this interaction might imply a violation of the Equivalence Principle. Our analysis show that evidence is found in the context of two different models of dark energy-dark matter interaction.Comment: Talk presented by O.B. at Encuentros Relativistas Espanoles 2007, Puerto de la Cruz, Tenerife, Spain, 10-14 September 2007. 6 pages, 3 figures and style fil

Black Holes and Galactic Density Cusps Spherically Symmetric Anisotropic Cusps

Aims: In this paper we study density cusps that may contain central black holes. The actual co-eval self-similar growth would not distinguish between the central object and the surroundings. Methods: To study the environment of a growing black hole we seek descriptions of steady `cusps' that may contain a black hole and that retain at least a memory of self-similarity. We refer to the environment in brief as the `bulge' and on smaller scales, the `halo'. Results: We find simple descriptions of the simulations of collisionless matter by comparing predicted densities, velocity dispersions and distribution functions with the simulations. In some cases central point masses may be included by iteration. We emphasize that the co-eval self-similar growth allows an explanation of the black hole bulge mass correlation between approximately similar collisionless systems. Conclusions: We have derived our results from first principles assuming adiabatic self-similarity and either self-similar virialisation or normal steady virialisation. We conclude that distribution functions that retain a memory of self-similar evolution provide an understanding of collisionless systems. The implied energy relaxation of the collisionless matter is due to the time dependence. Phase mixing relaxation may be enhanced by clump-clump interactions.Comment: 9 pp, 3 figs, accepted by A\&

Separating expansion from contraction: generalized TOV condition, LTB models with pressure and Λ\LambdaCDM

We discuss the existence of a dividing shell separating expanding and collapsing regions in spherically symmetric solutions with pressure. We obtain gauge invariant conditions relating not only the intrinsic spatial curvature of the shells to the ADM mass, but also a function of the pressure which we introduce that generalises the Tolman-Oppenheimer-Volkoff equilibrium condition, in the framework of a 3+1 spacetime splitting. We consider the particular case of a Lema\^itre-Tolman-Bondi dust models with a cosmological constant (a $\Lambda$-CDM model) as an example of our results.Comment: Proceedings of 'Invisible Universe International Conference', Paris, June 29- July 3, 2009 ; 5pp, 4 fig

Energy transfer from baryons to dark matter as a unified solution to small-scale structure issues of the Λ\LambdaCDM model

Using a semianalytic code, we show how baryon physics in a $\Lambda$CDM cosmology could solve the discrepancy between numerical predictions of dark matter haloes and observations, ranging from dwarf galaxies to clusters, without the need of nonstandard dark matter models as advocated, for example, by [Kaplinghat et al., Phys. Rev. Lett. 116, 041302, (2016)]. Combining well established results, we show, for the first time, how accounting for baryon physics, in particular dynamical friction mechanisms, leads to flat galaxy-cluster profiles and correlations in several of their properties, solves the so-called `diversity problem' and reproduces very well the challenging, extremely low-rising rotation curve of IC2574. We therefore suggest treating baryonic physics properly before introducing new exotic features, albeit legitimate, in the standard cosmological model.Comment: 10 pages, 4 figures, matching the accepted version on Phys. Rev.