The project aims to observationally exploit X-ray binaries, a research line in which our group it is one of the world leaders. These stellar systems, composed of a black hole (or a neutron star) and a solar-like star (companion), are unique laboratories to explore the behaviour of the matter and radiation under the most extreme gravitational fields. In particular, the gravity of the black hole is able to tear the material from the external layers of the companion, giving rise to the phenomenon of accretion. This physical process represents the most efficient form of energy production known. To characterise the accretion process is essential to understand the Universe, since it plays a crucial role in galactic and extra-galactic astrophysics.
Accreting black-holes and neutron stars in X-ray binaries provide an ideal laboratory for exploring the physics of compact objects, yielding not only confirmation of the existence of stellar mass black holes via dynamical mass measurements, but also the best opportunity for probing high-gravity environments and the physics of accretion; the most