Cross-match of the J-PAS, S-PLUS and J-PLUS surveys with the Dark Energy Spectroscopic Instrument (DESI)

• Grant number: 25/03825-8
• Support Opportunities: Scholarships in Brazil - Scientific Initiation
• Start date: May 01, 2025
• End date: December 31, 2025
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
• Principal Investigator: Luis Raul Weber Abramo
• Grantee: Roberta Vassallo Bordoni
• Host Institution: Instituto de Física (IF). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Associated research grant: 19/26492-3 - Science with the Brazilian robotic telescope, AP.ESP

Abstract

Photometric surveys are quite complete (the number of galaxies can reach ~10^{-2} h^3 Mpc^{-3}), but the quality of photometric redshifts implies, in practice, a complex selection of galaxy populations that can effectively be used by these surveys. In order to study the completeness of these surveys, it is useful to compare them to others, deeper and/or spectroscopic. In 2024 we had the release of the Early Data Release of the Dark Energy Spectroscopic Instrument (DESI), with 2847435 objects, of which 1718654 are galaxies, 117771 are quasars, and the rest are stars. Almost at the same time we also have a significant increase in the number of objects and the area covered by surveys such as S-PLUS and J-PAS. This Scientific Initiation project seeks, firstly, to introduce student Roberta V. Bordoni to the topic of astrophysical surveys, with a bias towards cosmology. At the same time, the student will also work with data from DESI, S-PLUS, J-PAS and J-PLUS, downloading catalogues, selecting objects, noting the relevant "flags" and cross-matching them. One of the objectives is to characterize the effective depth of these photometric surveys for different types of galaxies and quasars, for different redshifts. It will also be able to check the photometric redshifts obtained in these surveys. In a possible last step, it will be able to calculate the correlation function between the survey galaxies, in small areas where the selection is sufficiently homogeneous. (AU)