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## Abstract

The Standard Cosmological Model is generally accepted by the scientific community, there are still an amount of unresolved issues.
From the observable characteristics of the structures in the Universe,it should be possible to impose constraints on the cosmological parameters.
Cosmic Voids (CV) are a major component of the LSS and have been shown to
possess great potential for constraining DE and testing theories of gravity.
But a gap between CV observations and theory still persists.
A theoretical model for void statistical distribution as a function of size exists (SvdW)
However, the SvdW model has been unsuccesful in reproducing the results obtained from cosmological simulations.
This undermines the possibility of using voids as cosmological probes.
The goal of our thesis work is to cover the gap between theoretical predictions and measured distributions of cosmic voids.
We develop an algorithm to identify voids in simulations,consistently with theory.
We inspecting the possibilities offered by a recently proposed refinement of the SvdW
(the Vdn model, Jennings et al., 2013).
Comparing void catalogues to theory, we validate the Vdn model, finding
that it is reliable over a large range of radii, at all the redshifts
considered and for all the cosmological models inspected.
We have then searched for a size function model for voids identified in a distribution of biased
tracers. We find that, naively applying the same procedure used for the
unbiased tracers to a halo mock distribution does not provide success-
full results, suggesting that the Vdn model requires to be reconsidered
when dealing with biased samples. Thus, we test two alternative exten-
sions of the model and find that two scaling relations exist: both the
Dark Matter void radii and the underlying Dark Matter density contrast
scale with the halo-defined void radii. We use these findings to develop
a semi-analytical model which gives promising results.

Abstract

The Standard Cosmological Model is generally accepted by the scientific community, there are still an amount of unresolved issues.
From the observable characteristics of the structures in the Universe,it should be possible to impose constraints on the cosmological parameters.
Cosmic Voids (CV) are a major component of the LSS and have been shown to
possess great potential for constraining DE and testing theories of gravity.
But a gap between CV observations and theory still persists.
A theoretical model for void statistical distribution as a function of size exists (SvdW)
However, the SvdW model has been unsuccesful in reproducing the results obtained from cosmological simulations.
This undermines the possibility of using voids as cosmological probes.
The goal of our thesis work is to cover the gap between theoretical predictions and measured distributions of cosmic voids.
We develop an algorithm to identify voids in simulations,consistently with theory.
We inspecting the possibilities offered by a recently proposed refinement of the SvdW
(the Vdn model, Jennings et al., 2013).
Comparing void catalogues to theory, we validate the Vdn model, finding
that it is reliable over a large range of radii, at all the redshifts
considered and for all the cosmological models inspected.
We have then searched for a size function model for voids identified in a distribution of biased
tracers. We find that, naively applying the same procedure used for the
unbiased tracers to a halo mock distribution does not provide success-
full results, suggesting that the Vdn model requires to be reconsidered
when dealing with biased samples. Thus, we test two alternative exten-
sions of the model and find that two scaling relations exist: both the
Dark Matter void radii and the underlying Dark Matter density contrast
scale with the halo-defined void radii. We use these findings to develop
a semi-analytical model which gives promising results.

Tipologia del documento

Tesi di laurea
(Laurea magistrale)

Autore della tesi

Ronconi, Tommaso

Relatore della tesi

Correlatore della tesi

Scuola

Corso di studio

Ordinamento Cds

DM270

Parole chiave

Cosmology,cosmic voids,mass function,astrophysics,large scale structure,theory

Data di discussione della Tesi

19 Luglio 2016

URI

## Altri metadati

Tipologia del documento

Tesi di laurea
(NON SPECIFICATO)

Autore della tesi

Ronconi, Tommaso

Relatore della tesi

Correlatore della tesi

Scuola

Corso di studio

Ordinamento Cds

DM270

Parole chiave

Cosmology,cosmic voids,mass function,astrophysics,large scale structure,theory

Data di discussione della Tesi

19 Luglio 2016

URI

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