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Observational signatures of hot spots orbiting black hole mimickers
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Resumo(s)
This thesis focuses on analyzing specific observable imprints of static thin-shell gravastars and compare them to the observational signatures of a Schwarzschild black hole. The thin-shell model of the
gravastar is defined by two free parameters: the gravastar radius and the mass distribution ratio within
the thin-shell. We investigate the effects of these parameters as well as observation inclination and orbital radius, when these objects are orbited by a hot-spot, by using the GYOTO software, a numerical
backward ray-tracing code, to simulate the observational outcomes. For this astrophysical framework,
we find that all the parameters have different impacts on the observed features with exception of the mass
distribution, which plays a sub-dominant role, having a negligible impact. Our analysis also reveals that
the astrometrical observational properties of ultra-compact gravastars closely resemble those of other
ultra-compact objects, such as fluid stars and bosonic stars. However, low-compacticity configurations
exhibit a more prominent and intense plunge through image, in the time-integrated flux. Additionally,
ultra-compact gravastar configurations harbor light rings, being plausible candidates for mimicking black
holes, while low-compacticity configurations do not feature light rings and thus a similarity to black holes
is not guaranteed. These qualitative distinctions in observational properties between gravastars and blackhole spacetimes could potentially be discerned by the next generation of interferometric experiments in
gravitational physics.
Descrição
Tese de mestrado, Física (Astrofísica e Cosmologia), 2024, Universidade de Lisboa, Faculdade de Ciências
Palavras-chave
gravastar objetos compactos assinaturas observacionais hot spot buraco negro Teses de mestrado - 2024