Large-scale Structure and Galaxy Formation in non-standard Cosmologies

Abstract

We study the large-scale structure of alternative cosmologies, which intrinsically avoid the theoretical problems of the cosmological constant in the standard cold dark matter (CDM) cosmology. We focus on early dark energy (EDE) models and gravity, which are the typical examples of dark energy and modified gravity models respectively. We constrain the EDE model using measurements of cosmic microwave background and baryon acoustic oscillations, then use large-volume N-body simulations to study the structure formation and growth. EDE and CDM can be distinguished through the shape of matter power spectrum on large scales, as well as the halo mass function at high redshift. We run high-resolution N-body simulations of gravity in order to study in detail the properties of haloes and their environment. We find that halos less massive than have a more compact inner structure in gravity than in CDM. These low-mass haloes grow faster and contain substantially more subhaloes in gravity. We also measure the correlation between different halo environment definitions used in observations and the fifth force potential in gravity. Although the different ways to define environment do not agree with one another perfectly, they can provide useful guidance about how well a dark matter halo is screened. We also find that the screening of subhaloes in dark matter haloes is primarily determined by the environment, with the subhalo mass playing a minor role. Finally, we investigate and improve the H luminosity function predicted by semi-analytical galaxy formation model, GALFORM. The result is important for accessing the performance of Euclid redshift survey, which is one of the missions cosmological probe of accelerating cosmic expansion.