Astronomy Seminar Series
Arnaud De-Mattia, CEA Saclay
In this talk I will present the clustering analysis of the ELG (Emission Line Galaxy) sample from the eBOSS (extended Baryon Oscillation Spectroscopic Survey) program of the Sloan Digital Sky Survey and review the other clustering analyses of the eBOSS program, dedicated to Luminous Red Galaxies and Quasars. I will discuss theoretical, observational and analysis systematics, how they were estimated and mitigated, focusing on the improvements over the last release of the BOSS program in 2016. Specifically, I will start by presenting the extensive work of the eBOSS collaboration to test model predictions against N-body simulations. The different observational systematics of the eBOSS samples will be reviewed, as well as the adopted correction schemes and the new analysis techniques used to mitigate residual systematics. Different analysis assumptions and their impact on the clustering signal will be discussed. After a review of eBOSS legacy cosmological measurements, I will finish by drawing lessons and prospects for future galaxy surveys.
After graduating from an engineering school, Arnaud started a Ph.D. in observational cosmology at CEA Saclay, France, in October 2017. He has been working with the sample of Emission Line Galaxies from the eBOSS (extended Baryon Oscillation Spectroscopic Survey) program of the Sloan Digital Sky Survey, one of the two largest ELG samples to date. He studies the spatial distribution of these galaxies to put constraints on the expansion history of the Universe and test General Relativity on large scales.
In practice, he creates clustering catalogs of galaxy position and weight correcting for known observational systematics, performs a Fourier analysis of their anisotropic 2-point correlation function, sets up new methods to correct for remaining observational systematics or analysis biases which he assesses from simulations, and fits the obtained signal with perturbation theory predictions, tested against N-body simulations. After his Ph.D. Arnaud would like to keep working on statistical methods to extract maximum information out of spectroscopic surveys, allowing combinations of different cosmological probes and tests of extensions to LCDM.