My work is mainly focused on the study of compact objects like black holes and neutron stars (and also gravastars), using the General Relativity theory. The study of the gravitational waves emitted by such objects is currently of great astrophysical interest, and it can also give us valuable information on the behavior of matter under extreme conditions such as the interior of a neutron star.
The study of gravitational waves need general relativity and perturbation theory. According to Einstein's theory, perturbed compact objects should emit gravitational waves. These waves are riples in the fabric of spacetime itself, that propagate with the speed of light. Indirect observations have already been made in the past, for instance with the binary pulsar PSR 1913+16.
The first direct observation of gravitational waves happened on September 14th 2015 and it was announced by the LIGO team on February 11th 2016. The observations provided evidence for the existence of black holes, binary black holes and the validity of general relativity.
There are gravitational wave detectors all over the world. In Brazil, the Mario Schenberg detector is currently being developed.
More information and interesting links