Black holes

Accretion onto black holes is one of the most powerful sources of energy for astrophysical objects. We study several dynamical processes related to black hole accretion and its electromagnetic emission. Specific themes of interest are:

Tidal Disruption events

Tidal disruption events occur when a star approaches a black hole within a distance such that the immense tidal forces of the hole overcome the internal gravity of the star and rip it apart. These events appear also as bright, transient emission over a wide range of electromagnetic frequencies, typically in the UV and soft X-rays, but occasionally also in the gamma and radio regime. The combination of electromagnetic and gravitational emission allows us to study the elusive intermediate massive black holes.

Black hole binaries

We study how the interplay between binary black holes and the gaseous discs that surround them can lead or not to their merger, and what would be the electromagnetic emission associated with such processes. We study both supermassive black hole binaries (which may be relevant for the LISA interferometer) and stellar mass black hole binaries (relevant for LIGO/Virgo).

Black hole spin evolution and disc warping

Relativistic frame dragging (resulting in Lense-Thirring precession) can warp the accretion disc around a spinning black hole. We study both analytically and through hydrodynamical simulations the warping and tearing of such a disc, relating the resulting configuration to possible observed features in the spectrum of accretion black hole systems, such as Quasi Periodic Oscillations (QPO) in X-ray binaries.