Black holes

Black holes are possibly the most intriguing objects in the Universe. They deform the space-time around them and prevent everything, including light, from escaping. They come in different sizes or, equivalently, they have different masses. 

Observational evidence has been gathered for stellar mass black holes, with masses of about 10 solar masses, which are produced by the core collapse of massive stars and appear as X-ray sources when they accrete from their companion in binary systems, as well as for supermassive black holes, with masses of millions to billions of solar masses, which are found at the centres of galaxies and power the tremendous luminosities of active galactic nuclei. Both classes of black holes are ubiquitous in galaxies, including the Milky Way.

Black holes of intermediate mass have been theoretically predicted, but so far only tentative observational evidence exists, in the form of either ultra-luminous X-ray sources or a cusp in the density profiles of dense star clusters.

Thanks to its proximity and the large amoung of available observations, the centre of the Milky Way represents a unique laboratory in which to study the dynamics of stellar systems surrounding black holes. Here deep infrared observations have revealed the existence of young massive stars orbiting the 4 million solar masses black hole, raising the question of how star formation can proceed in such an unfavourable environment and how it couples to gravitational interactions.

Using high accuracy N-body simulations, our group studies the processes of star formation and dynamical evolution around supermassive black holes, providing strong theoretical predictions to be tested against observations. This is a particularly favorable time for such studies given the increasing quantity and quality of observations. In addition, a gas cloud currently observed on a very eccentric orbit around the supermassive black hole will reach its pericentre at theend of 2013, allowing unprecedented studies of tidal effects and gas accretion.