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| Author(s): |
Caroline Macedo Guandalin
Total Authors: 1
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| Document type: | Doctoral Thesis |
| Press: | São Paulo. |
| Institution: | Universidade de São Paulo (USP). Instituto de Física (IF/SBI) |
| Defense date: | 2021-12-14 |
| Examining board members: |
Luis Raul Weber Abramo;
Emanuele Castorina;
Pedro Tonnies Gil Ferreira;
Marcos Vinicius Borges Teixeira Lima;
Miguel Boavista Quartin
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| Advisor: | Luis Raul Weber Abramo; Philip James Bull |
| Abstract | |
We have seen an unprecedented development in the field of cosmology, in the past decades, with the development of increasingly detailed cosmic microwave background maps. Notwithstanding, the amount of information one can extract from those two-dimensional maps is limited when compared to what can be achieved through the three-dimensional mapping obtained with galaxy surveys. The spatial dark matter distribution inferred with these surveys depends on the highly non-linear gravitational collapse, which can be incorporated in our three-dimensional description through $N$-body simulations (usually performed within Newtonian gravity) up to the tens of Mpc scales. In contrast, scales at the order of hundreds of Mpc are free from astrophysical effects and can be accurately described with perturbation theory. At these scales, relic features characteristic of primordial universe physics are left in the $n$-point statistics of dark matter tracers (e.g. galaxies and halos), and we can obtain novel gravitational effects through a theory-observables connection (the latter which are based on a set of fundamental observables such as redshift and observed angles on the sky). Primarily, we explore the relativistic anisotropies in the dark matter halo distribution that emerge after connecting the observed redshift with its theoretical general relativistic prediction. We focus on the power-spectrum dipole (2-point statistics) signal that appears after cross-correlating different halo populations (i.e. different masses) obtained from a weak-field relativistic $N$-body simulation. We make a complete presentation of the details necessary to extract essential parameters to model and interpret the results on an observed light cone. From an observational perspective, while it is desirable to have high-precision redshifts, we also require a large volume coverage to reach the necessary scales at which relativistic and primordial non-Gaussian effects (the latter is a characteristic feature of inflationary models) are manifested. However, when dealing with discrete dark matter tracers, we must acquire a large number of observations for the $n$-point signal to overcome its noise. Large volumes can be densely mapped through the so-called photometric redshifts, at the cost of redshifts with spectroscopic precision. Therefore, our second objective is to calibrate photometric redshifts utilising the clustering information of both galaxies and neutral hydrogen intensity mapping. We assess the ability of the bispectrum (3-point statistics) to recover the redshift distribution parameters, and we compare the results with the power spectrum. We also verify, for both 2- and 3-point statistics, how this clustering redshifts method depends upon the foreground contamination present in the neutral hydrogen maps. (AU) | |
| FAPESP's process: | 18/10396-2 - Statistical techniques for future surveys: extracting primordial physics out of the large-scale structure |
| Grantee: | Caroline Macedo Guandalin |
| Support Opportunities: | Scholarships in Brazil - Doctorate |