The Environment of QSOs Triplets at 1 < z < 1.5

• Ano de defesa: 2020
• Autor(a) principal: Vicentin, Marcelo Ciani
• Tipo de documento: Dissertação
• Tipo de acesso: Acesso aberto
• Idioma: eng
• Instituição de defesa: Biblioteca Digitais de Teses e Dissertações da USP
• Palavras-chave em Português: catálogos; catalogues; galáxias: distâncias e redshifts; galáxias: estatística; galáxias: estruturas; galáxias: fotometria; galaxies: statistics; galaxies: structures; galaxy: photometry,galaxies: distances and redshifts; methods: data analysis.; métodos: análise de dados; quasares: geral; quasars: general; surveys
• Link de acesso: https://www.teses.usp.br/teses/disponiveis/14/14131/tde-04112020-150928/

We present an analysis of the environment of six QSO triplets at 1 < z < 1.5 by analyzing multiband (r,i,z, or g,r,i) images obtained with Megacam at the CFHT telescope, aiming to investigate whether they are associated or not with galaxy protoclusters. This was done by using photometric redshifts trained using the highly accurate photometric redshifts of the COSMOS2015 catalogue. To improve the quality of our photometric redshift estimation, we included in our analysis mid-infrared photometry (3.6 and 4.5m) from the unWISE survey available for our fields and the COSMOS survey. This approach allowed us to obtain good photometric redshifts, with dispersions of 0.04 for our six fields. Our analysis setup was reproduced on lightcones constructed from the Millennium Simulation data and the latest version of the L-GALAXIES semi-analytic model to verify the protocluster detectability in such conditions. The density field in a redshift slab containing each triplet was then analyzed with a Gaussian kernel density estimator. We find that all but one of our triplets tend to avoid overdense regions. In one case the triplet is associated with a possible protocluster at z= 1.12.