Effects of tidal gravitational fields in clustering dark energy models

TL;DR

This paper investigates how tidal shear influences clustering dark energy models using the extended spherical collapse model and Zel'dovich approximation, finding small effects that align with previous smooth dark energy results.

Contribution

It extends prior work by analyzing tidal shear effects on clustering dark energy within a linear-scale, self-consistent framework, highlighting their minor impact on structure formation.

Findings

Tidal shear effects are of the order of percent or less.

Including dark energy perturbations improves agreement with ΛCDM.

Effects on halo number density are small and consistent with previous models.

Abstract

We extend a previous work by Reischke et al., 2016 by studying the effects of tidal shear on clustering dark energy models within the framework of the extended spherical collapse model and using the Zel'dovich approximation. As in previous works on clustering dark energy, we assumed a vanishing effective sound speed describing the perturbations in dark energy models. To be self-consistent, our treatment is valid only on linear scales since we do not intend to introduce any heuristic models. This approach makes the linear overdensity $\delta_{\rm c}$ mass dependent and similarly to the case of smooth dark energy, its effects are predominant at small masses and redshifts. Tidal shear has effects of the order of percent or less, regardless of the model and preserves a well known feature of clustering dark energy: When dark energy perturbations are included, the models resemble better the $\Lambda$CDM evolution of perturbations. We also showed that effects on the comoving number density of halos are small and qualitatively and quantitatively in agreement with what previously found for smooth dark energy models.