Effects of shear and rotation on the spherical collapse model for clustering dark energy

Abstract

In the framework of the spherical collapse model we study the influence of shear and rotation terms for dark matter fluid in clustering dark energy models. We evaluate, for different equations of state, the effects of these terms on the linear overdensity threshold parameter, δ c , and on the virial overdensity, ∆ V . The evaluation of their effects on δ c allows us to infer the modifications occurring on the mass function. Due to ambiguities in the definition of the halo mass in the case of clustering dark energy, we consider two different situations: the first is the classical one where the mass is of the dark matter halo only, while the second one is given by the sum of the mass of dark matter and dark energy. As previously found, the spherical collapse model becomes mass dependant and the two additional terms oppose to the collapse of the perturbations, especially on galactic scales, with respect to the spherical non-rotating model, while on clusters scales the effects of shear and rotation become negligible. The values for δ c and ∆ V are higher than the standard spherical model. Regarding the effects of the additional non-linear terms on the mass function, we evaluate the number density of halos. As expected, major differences appear at high masses and redshifts. In particular, quintessence (phantom) models predict more (less) objects with respect to the ΛCDM model and the mass correction due to the contribution of the dark energy component has negligible effects on the overall number of structures.

Skewness of matter distribution in clustering dark energy cosmologies

“…The solution found for D 1 is then later used as a source term in Eq. (12). We finally solve numerically Eq.…”

“…It is worth noting that the system (11) and (12) has been obtained for a single gravitating fluid (with pressure P and speed of sound c 2 a ) described by (2)- (4). At this point the quantities H, w and c 2 a have to be specified in order to study a specific model.…”

“…In some approaches the DE speed of sound can evade the canonical value c 2 s DE = 1 (see examples in Refs. [2][3][4][5][6][7]) and therefore leaving imprints on structure formation [8][9][10][11][12][13][14][15][16][17][18][19][20].…”

Accurate mass and velocity functions of dark matter haloes

“…More precise predictions are actively being sought (e.g. Pace et al 2014;Pace, Batista & Del Popolo Rei;Del Popolo et al 2017). Eventually we will converge towards an ultimate physical model for the halo mass function.…”

Constraints to Dark Energy Using PADE Parameterizations

“…Moreover, the growth of cosmic structures are also affected by perturbations of DE when we deal with dynamical DE models with time varying EoS parameter w 1 de ¹ - (Erickson et al 2002;Bean & Doré 2004;Hu & Scranton 2004;Basilakos & Voglis 2007;Mota et al 2007;Ballesteros & Riotto 2008;Basilakos et al 2009aBasilakos et al , 2010Gannouji et al 2010;Sapone & Majerotto 2012;Batista & Pace 2013;Dossett & Ishak 2013;Basse et al 2014;Batista 2014;Nesseris & Sapone 2015;Pace et al 2014aPace et al , 2014bBasilakos 2015;Mehrabi et al 2015aMehrabi et al , 2015bMehrabi et al , 2015cMalekjani et al 2015Malekjani et al , 2017.…”