Estimating the two-point correlation function of a 3D galaxy distribution.

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Title: Estimating the two-point correlation function of a 3D galaxy distribution.
Author: Gonzalez Ateca, Marcos
Contributor: University of Helsinki, Faculty of Science
Publisher: Helsingin yliopisto
Date: 2020
Language: eng
Thesis level: master's thesis
Degree program: Alkeishiukkasfysiikan ja astrofysikaalisten tieteiden maisteriohjelma
Master's Programme in Particle physics and Astrophysical Sciences
Magisterprogrammet i elementarpartikelfysik och astrofysikaliska vetenskaper
Specialisation: Alkeishiukkasfysiikka ja kosmologia
Particle Physics and Cosmology
Elementarpartikelfysik och kosmologi
Discipline: none
Abstract: The distribution of matter in space is not homogeneous. Large structures such as galaxy groups, clusters or big empty spaces called voids can be observed at large scales in the Universe. The large scale structure of the Universe will depend on both the cosmological parameters and the dynamics of galaxy formation and evolution. One of the main observables that allow us to quantify this structure is the two-point correlation function, with which we can trace different galaxy properties such as luminosity, stellar mass and also, it enables us to track its evolution with redshift. In galaxy surveys, we do not obtain the location of galaxies in real space. We obtain our data in what it is called redshift space. This redshift space can be defined as a distortion of the real space generated by the redshift introduced by the peculiar velocities of galaxies and from the Hubble expansion of the Universe. Therefore, the distribution of galaxies in redshift space will look different from the one obtained in real space. These differences between both spaces are small but not negligible, and they depend strictly on the cosmology. In this work, we will assume a ΛCDM cosmology. Therefore, in order to find the different 1-dimensional or 2-dimensional correlations functions, we will use the most updated version of the code provided by the Euclid consortium, which belongs officially to the ESA Euclid mission. Moreover, we will also need different galaxy catalogues. These catalogues have already been simulated and they are called Minerva mocks, which are a set of 300 different cosmological mocks produced with N-body simulations. Finally, as there is a well-defined relation between real and redshift space, one could also assume that there is a relation between the two-point correlation functions in both real and redshift space. In this project, we will prove that the real-space one-dimensional two-point correlation function, which is the physically meaningful one, can be derived from the two-dimensional two-point correlation function in redshift space following a geometrical procedure independent of approximations. This method, in theory, should work for all distance scales.
Subject: two-point correlation function
redshift space
projected correlation function
deprojection procedure

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