Simulação e busca automatizada de arcos gravitacionais

• Autor(a) principal: Brandt, Carlos Henrique
• Data de Publicação: 2012
• Tipo de documento: Dissertação
• Idioma: por
• Título da fonte: Biblioteca Digital de Teses e Dissertações do LNCC
• Texto Completo: https://tede.lncc.br/handle/tede/146
• topic: Gravitação - Cosmologia; Simulação (Computadores); Computer simulation - Cosmology; Gravitation; CNPQ::CIENCIAS EXATAS E DA TERRA::ASTRONOMIA::ASTROFISICA EXTRAGALACTICA::COSMOLOGIA

Gravitational arcs provide important tools for cosmology and astrophysics, and have been used to constrain cosmological parameters and the structure of galaxies and galaxy clusters. However, these objects are rare and challenging to detect. Wide field imaging surveys with good imaging quality, such as the Dark Energy Survey (DES), will increase the current number of known arc systems by about an order of magnitude. Algorithms for automated detection (arc-finders) are absolutely necessary since currently available data volumes are already beyond human capabilities. Besides, it is necessary to have objective methods capable of generating reproducible results. Furthermore, it is essential to perform realistic arc simulations to test the analysis tools, both arc-finders as well as those aimed to extract physical information from these objects. The main contribution of this work was the development of a gravitational arc simulator for the DES project, named AddArcs. The simulator generates arcs based on N-body simulations and parameters derived from observational data. Observational effects can be added according to the properties of the instrument. Regarding the automated detection of arcs, we review an algorithm from the literature and apply it to a set of images, tuning its parameters for each set. Some image processing methods often used for the identification of astronomical objects were also reviewed. Both the methods for simulation and image processing were integrated into a library of tools for astronomical data processing named SLtools. The AddArcs simulator enabled the inclusion of fairly realistic gravitational arcs on the DES simulated images and catalogs. It also lead to an estimate of the abundance of arcs expected to be observed by DES.