Dark Energy and Void Dynamics - An interplay between cosmological parameters

Marchesini, Enrico (2025) Dark Energy and Void Dynamics - An interplay between cosmological parameters. Bachelor's Thesis, Astronomy.

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Abstract

Cosmic voids, the vast underdense regions dominating the cosmic volume, provide an excellent probe to test cosmological scenarios, thanks to their extreme sensitivity to cosmological parameters. In this study, the velocity fields in voids have been investigated in five different cosmological scenarios, in order to study how changes in the cosmological parameters reflect in void dynamics. Starting from Quijote N-body simulations at redshift z = 0, the probability and cumulative distributions of the density fields were obtained, so that differences in the density distributions could be studied in the various scenarios. Then, individual voids were analyzed in the five scenarios, in order to investigate how the differences in the density fields reflected in the outflow dynamics. In order to obtain density and velocity fields suited for this analysis, the fields from Quijote were turned into volume-weighted via DTFE, and smoothed through Gaussian filtering in Fourier space. It was then possible to isolate thee voids per scenario, extract their velocity profiles, and derive an additional term to Hubble, H∗, quantifying the strength of the local expansion observed in the voids’ interior. The results show that a scenario with a higher matter concentration leads to significantly higher values of H∗, while changes in the dark energy equation of state w or the presence of primordial non-Gaussianities don’t bring significant changes in the velocity profiles. These findings suggest that the present-day energy contents of the Universe have a dominating effect on void’s outflow dynamics.

Item Type:	Thesis (Bachelor's Thesis)
Supervisor name:	Weijgaert, M.A.M. van de
Degree programme:	Astronomy
Thesis type:	Bachelor's Thesis
Language:	English
Date Deposited:	16 Jul 2025 06:59
Last Modified:	16 Jul 2025 06:59
URI:	https://fse.studenttheses.ub.rug.nl/id/eprint/36304

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