Lobo, Francisco Sabélio Nobrega, 1966-Rosa, João LuísCordeiro, Daniela Sofia Jorge2024-11-222024-11-2220242024http://hdl.handle.net/10400.5/95556Tese de mestrado, Física (Astrofísica e Cosmologia), 2024, Universidade de Lisboa, Faculdade de CiênciasThis 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.porgravastarobjetos compactosassinaturas observacionaishot spotburaco negroTeses de mestrado - 2024master thesis203683455