Formación - Tesis de Máster

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Cosmology with galaxy surveys

Estado: ongoing

Estudiante(s): Arnau Pujol
Director(s): Enrique Gaztañaga
One of the fundamental goals of Cosmology is to understand the matter and energy content of the Universe, and the way its contents determine the growth of fluctuations and the evolution of the observed structure. In order to tackle these questions, we need to study the overall structure and evolution of the universe and its constituents. We thus need to sample large enough volumes as to be meaningful and representative. We also need to probe different epochs to learn about its evolution. Observationally, these requirements are only met by big surveys that probe wide areas and a large fraction of the local Universe and that are deep enough to sample structures at high redshift. In the last few years, the number of surveys has been impressive and impossible to review here in detail. The most useful of them in terms of cosmological and large-scale structure applications have been the detailed redshift surveys of the local universe. The Two-Degree Field Galaxy Redshift Survey (2dFGRS; Colless et al 2001) and the Sloan Digital Sky Survey (SDSS; York et al 2000) have measured many hundreds of thousands of galaxy spectra. This has resulted in a major improvement in our knowledge of the galaxy population through, for example, the galaxy luminosity function (e.g., Norberg et al 2002; Blanton et al 2003), the galaxy power spectrum (e.g. Cole et al 2005; Tegmark et al 2004a), galaxy clustering (e.g., Norberg et al 2001; Gaztañaga 2002; Zehavi et al 2004, Cabre & Gaztanaga 2008), clusters of galaxies (e.g., de Propis et al 2002; Bahcall et al 2003), the cosmic star formation history (e.g., Baldry et al 2002; Glazebrook et al 2003), galaxy biasing (e.g., Verde et al 2002; Tegmark et al 2004a, Gaztañaga et al 2005), weak lensing (e.g., Fischer et al 2000; Gaztañaga 2003; Hirata et al, 2004), strong lensing (e.g., Inada et al 2003).... In this project we want to focus in biasing, ie how light from galaxies trace the underlaying dark matter (DM) distribution. The goal is to study how to best measure (or model) biasing evolution for current and upcoming galaxy surveys, such as SDSS, DES and PAU. We need to characterize biasing as a function of cosmic time and galaxy properties such as spectral type, color, morphology, magnitude or spatial environment. The biasing parameters can be linked to models of galaxy formation and can also be used to provide new clues on the nature of DM and DE (i.e. through new standard rulers or the evolution of the growth factor). The study can be done by measuring redshift space distortions (due to peculiar velocity of galaxies), the higher order clustering of galaxies and also by the comparison of the galaxy distribution to weak lensing mass reconstruction. We plan to use the N-body simulation run in our group (ie see MICE: which include both the dark matter distribution and mock galaxy distribution form a variety of prescriptions and models of galaxy formation.