Semi-analytic galaxy formation in coupled dark energy cosmologies

TL;DR

This study investigates how coupled Dark Energy models influence galaxy formation and properties, using simulations and semi-analytic models, revealing weak effects on galaxy statistics but potential for galaxy bias and velocities to distinguish models.

Contribution

It introduces modifications to semi-analytic galaxy formation models to account for coupled Dark Energy effects and assesses their impact on galaxy statistics.

Findings

Galaxy statistical properties are weak probes of coupled DE models.

Galaxy bias and pairwise velocities are sensitive to coupled DE.

Standard SAM predictions are similar to coupled-DE models for galaxy statistics.

Abstract

Among the possible alternatives to the standard cosmological model ($\Lambda$CDM), coupled Dark Energy models postulate that Dark Energy (DE), seen as a dynamical scalar field, may interact with Dark Matter (DM), giving rise to a "fifth-force", felt by DM particles only. In this paper, we study the impact of these cosmologies on the statistical properties of galaxy populations by combining high-resolution numerical simulations with semi-analytic models (SAM) of galaxy formation and evolution. New features have been implemented in the reference SAM in order to have it run self-consistently and calibrated on these cosmological simulations. They include an appropriate modification of the mass temperature relation and of the baryon fraction in DM haloes, due to the different virial scalings and to the gravitational bias, respectively. Our results show that the predictions of our coupled-DE SAM do not differ significantly from theoretical predictions obtained with standard SAMs applied to a reference $\Lambda$CDM simulation, implying that the statistical properties of galaxies provide only a weak probe for these alternative cosmological models. On the other hand, we show that both galaxy bias and the galaxy pairwise velocity distribution are sensitive to coupled DE models: this implies that these probes might be successfully applied to disentangle among quintessence, $f(R)$-Gravity and coupled DE models.