No presente artigo é introduzido, de forma didática e simplificada, evitando-se grandes perdas de conteúdo, um dos formalismos mais utilizados de representação geométrica de horizontes de eventos e singularidades, conhecido como ‘diagrama de Carter-Penrose’. São diagramas que simplificam e agilizam a percepção do espaço-tempo ao redor e no interior de horizontes de evento. Para chegar à descrição físico-geométrica desses diagramas, inicialmente se explicará o formalismo de remoção de singularidades de coordenada em horizontes de eventos para uma determinada métrica e, em seguida, as coordenadas de Finkelstein e de Kruskal-Szekeres. Exemplos de diagramas de Penrose para alguns tipos de buracos negros serão apresentados (Schwarzschild, Reissner-Nordström e Kerr-Newman), além das possibilidades referentes a buracos brancos e buracos de minhoca.

In the present article it is introduced in a didactic and simplified manner, avoiding major content losses, one of the most used formalisms of geometric representation of event horizons and singularities, known as ‘Carter-Penrose diagram’. Those are diagrams that simplify and streamline the perception of the spacetime around event horizons and also inside black holes. Before present the physical and geometrical description of such diagrams, initially it will be explained the formalism for removal of coordinate singularities of event horizons for a particular metric; after it will be introduced the coordinates of Finkelstein and Kruskal-Szekeres. Examples of Penrose diagrams for some types of black holes will be presented (Schwarzschild, Reissner-Nordström and Kerr-Newman), beyond the possibilities regarding white holes and also wormholes.

The aim of this work is to present a possible way to estimate observational electromagnetical clues in the spectrum of quasars and microquasars due to the presence of extra dimensions. Here we analyze two possible ways to detect these electromagnetic signals: by the brane corrected accretion mechanism and by production of electromagnetic KK modes. We show that for the static black hole accretion case, the brane corrections cause a extremelly small variation in the luminosity of the quasar. For the electromagnetic KK modes case, apparently the answer for the biggest quasars is positive and on the other hand, the possibility that microquasars can present constraints on extra-dimensional gravity in their spectra is less probable.