Observational mission: NTT/EFOSC2 - ESO/Chile

• Grant number: 23/02731-4
• Support Opportunities: Scholarships abroad - Research
• Start date: July 28, 2023
• End date: August 08, 2023
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Positional Astronomy and Celestial Mechanics
• Principal Investigator: Ramachrisna Teixeira
• Grantee: Ramachrisna Teixeira
• Host Investigator: Christine Ducourant
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil
• Institution abroad: European Southern Observatory, La Serena (ESO), Chile

Abstract

Since 2016, the European Space Agency (ESA) and the Gaia Data Processing Analysis Consortium (Gaia DPAC) release worldwide and at the same time approximately every 2 years, a huge amount of observational data of the highest quality. DR3 delivered the astrometry and photometry of almost 2 billion objects, including more than 1.8 million quasars. With the aim of producing a unique and statistically significant sample of gravitational lenses, we created in 2016, the "Gaia Gravitational Lens" (Gaia GraL) group involving ~20 researchers from several countries. With a census of these structures covering the entire sky with an unprecedented level of resolution (180 mas), we intend to contribute to studies on the evolution of the population of deflecting galaxies and determination of cosmological parameters, including H0, which presents discrepancies when determined according to a strategy or other. The objective of this FAPESP project is carry out an observational mission, 7 nights, at NTT/EFOSC2 - ESO - La Silla - Chile, aiming at the spectroscopic confirmation of strong gravitational lensing of quasars in the southern hemisphere and measurements of "redshifts" of the components. Candidates were selected from astrometric and photometric data from the Gaia space mission (DR2 and DR3) and from the compilation of published lists of quasars not necessarily spectroscopically confirmed. So far, we've confirmed 75 lenses using multiple telescopes: 17 lenses with four components and 58 with two components (as of August 2022 numbers). The group increased by more than 20% the database of known gravitational lenses, which is a very significant contribution to knowledge of these objects and a first step towards an independent and more robust determination of the H0 constant. Undoubtedly, they also attest to an excellent success rate for our strategy in defining the targets. (AU)