Fingerprints of Anomalous Primordial Universe on the Abundance of Large Scale Structures

TL;DR

This paper investigates how anomalous features in primordial inflation models influence the abundance and distribution of large-scale structures in the universe, offering potential solutions to existing cosmological tensions.

Contribution

It provides a model-independent framework linking primordial features to structure abundance and explores their observational implications, including asymmetries and bounds from quasar data.

Findings

Localized features can address the missing satellite problem.

Hemispherical asymmetry leads to directional dependence in structure abundance.

Upper bound on dipole asymmetry spectral index from quasar observations.

Abstract

We study the predictions of anomalous inflationary models on the abundance of structures in large scale structure observations. The anomalous features encoded in primordial curvature perturbation power spectrum are (a): localized feature in momentum space, (b): hemispherical asymmetry and (c): statistical anisotropies. We present a model-independent expression relating the number density of structures to the changes in the matter density variance. Models with localized feature can alleviate the tension between observations and numerical simulations of cold dark matter structures on galactic scales as a possible solution to the missing satellite problem. In models with hemispherical asymmetry we show that the abundance of structures becomes asymmetric depending on the direction of observation to sky. In addition, we study the effects of scale-dependent dipole amplitude on the abundance of structures and, using the quasars data, we find the upper bound $n_A<0.6$ for the spectral index of the dipole asymmetry. In all cases there is a critical mass scale $M_c$ in which for $M<M_c (M> M_c)$ the enhancement in variance induced from anomalous feature decreases (increases) the abundance of dark matter structures in Universe.