Determination of metallicity and chemical abundances in active galactic nuclei (CADA Project)

• Grant number: 22/07066-6
• Support Opportunities: Regular Research Grants
• Duration: May 01, 2023 - April 30, 2025
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Extragalactic Astrophysics
• Principal Investigator: Oli Luiz Dors Junior
• Grantee: Oli Luiz Dors Junior
• Host Institution: Instituto de Pesquisa e Desenvolvimento (IP&D). Universidade do Vale do Paraíba (UNIVAP). São José dos Campos , SP, Brazil
• Associated scholarship(s): 23/10182-0 - Determination of metallicity and chemical abundances in Active Nuclei of Galaxies (Projeto CADA), BP.TT

Abstract

Active Galactic Nuclei (AGNs) present in their spectra prominent emission lines, observed with high signal/noise and in a wide spectral range, emitted by elements such as hydrogen, helium and metals (O, N, C, etc). The ratio between the intensity of these lines allows us to estimate the metallicity (Z), metal abundances, as well as other properties such as electron temperature, electron density and the degree of ionization of the gas phase of these objects. The facility of measuring these lines and, after, determining some physical properties, combined with the high luminosity of these objects, make AGNs play an essential role in the study of the chemical evolution of galaxies over the Hubble time, as well as, of the Universe. On this scenario, this project proposes a study of chemical abundances of AGNs located in a wide range of redshift. Additionally, using observational data available in the literature, combined with photoionization model results and new methods based on direct electron temperature estimates, it is intended to estimate still unknown chemical abundances of some elements (e.g. N, C) in AGNs, and derive semi-empirical calibrations between broad and narrow emission lines more reliable than those proposed in the literature. Finally, it is also goal of this project to run simulations of photometric observations based on photoionization models that, combined with observational data available in the literature of galaxies in the redshift range (5 < z < 7), will provide evidence of which class of objects (i.e. AGNs, star-forming galaxies) were responsible for the reionization of the Universe. (AU)