Angular Scale of Baryonic Acoustic Oscillations from SDSS Data

Name: Ranier Menote Lemes Silva
Type: MSc dissertation
Publication date: 26/08/2021

Namesort descending Role
Valerio Marra Advisor *

Examining board:

Namesort descending Role
Armando Bartolome Bernui Leo External Examiner *
Davi Cabral Rodrigues Internal Examiner *
Oliver Fabio Piattella Internal Examiner *
Valerio Marra Advisor *

Summary: Most data analyses assume a cosmological model and, although these methods work well, it is important to verify their consistencies in a model-independent way. This discussion between model dependent and independent analyses has been intensified over the last years, with the increasing tension between the parameters deduced from early and late universe observable. The strongest tension in cosmology today regards the determination of the Hubble constant, the present-day expansion rate of the universe [1, 2, 3]. Determinations from the cosmic microwave background and Cepheids-calibrated supernovae Ia show a disagreement at about 4 sigma level. It is then important to measure the cosmic expansion through alternative techniques such as galaxy clustering. As predicted by the ΛCDM model, it must exist a preferable scale imprinted in the distribution of galaxies (called Sound Horizon). These Baryonic Acoustic Oscillations (BAO) can be measured by the spatial correlation function, but that assumes a cosmological model to calculate the distances between the galaxies. An alternative is to measure the angular correlation function without assuming a cosmological model, as pioneered by [4, 5, 6] which analyzed the data from Sloan Digital Sky Survey (SDSS) collaboration. The results from the angular correlation
function analysis showed tension with respect to the one from the spatial correlation function.
Here, we analyze the final data releases from the BOSS and eBOSS surveys in order to investigate this tension. While we use an approach similar to [6], we improve on the methodology and develop a new analysis pipeline so as to provide an independent analysis.
We confirm, in part, the tension between the angular and spatial correlation function analyses. Finally, we use the measurements of the BAO scale in order to constrain the standard model parameters.

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