Stars in the galactic centre [Elektronische Ressource] : sources and probes of the accretion flow / Jorge R. Cuadra Stipetich

Stars in the Galactic Centre:Sources and Probes of the Accretion FlowDISSERTATIONder Fakult at fur Physikder Ludwigs-Maximilians-Universit at Munc henzur Erlangung des GradesDoktor der NaturwissenschaftenDr. rer. nat.vorgelegt vonJorge R. Cuadra Stipetichaus San Bernardo, ChileMunc hen, den 26. Oktober 2006.1. Gutachter: Prof. R. A. Sunyaev2.hter: Prof. R. BenderTag der mundlic hen Prufung: 24. Oktober 2006\Now there’s a look in your eyesLike black holes in the sky"(Roger Waters)ivAbstract6In the centre of our Galaxy lies Sgr A*, a 3:5 10 solar mass black hole,immersed in a star cluster with dozens of massive stars. The very low luminosityof Sgr A*, and the presence of young stars in the close proximity of a super-massive black hole, make the Galactic centre a very interesting region on itsown. Moreover, its proximity allows the study of the physics of galactic nucleiwith a level of detail unattainable in any other system.In this thesis, we rst show that the interaction of massive stars with anaccretion disc would appear as strongly variable emission in the near infra-red.Since observations have not shown this variability, we strongly constrain thecurrent existence of such a disc in the Galactic centre. We argue however thata massive gaseous disc existed around Sgr A* only a few million years ago.The evidence for this idea comes from the presence of young massive stars intwo stellar discs.