MASSIVEBAYES · Bayesian inference of massive black hole binaries formation and evolution scenarios with gravitational waves

Bayesian inference of massive black hole binaries formation and evolution scenarios with gravitational waves

The scope of my project is to use gravitational wave (GW) observations to answer open questions in astrophysics and cosmology. To achieve this, I propose to use the GW signals generated by the coalescence of massive black hole binaries (MBHBs) detected by the forthcoming Laser Interferometer Space Antenna (LISA). In the standard cosmological scenario, dark matter halos merge leading to the structure formation along the filaments of the cosmic web. These regions are the birthplace of the first seed black holes (BHs) and proto-galaxies that grow together through episodes of accretion and merger leading to the massive BHs (MBHs) that we currently observe in the center of galaxies. MBHs are expected to interact with their host galaxies, leading to a complex evolutionary path where each actor influences the other. For example, MBHs can grow throughout accretion phases while the in-falling gas powers strong jets and disk winds that act as a feedback mechanism on the host galaxy. If the galaxies are brought sufficiently close, the MBHs residing at their centers might bind and form a binary that will eventually coalesce emitting GWs. In ~2034 LISA, the third Large class mission of the European Space Agency (ESA), will be able to observe GWs from the coalescence of MBHBs in the milli-hertz domain throughout the entire Universe. MBHBs are one of the core targets of LISA mission: coalescing at a typical frequency of milli-hertz, these sources are not accessible to ground-based (present and future) GW detectors operating in the frequency band above few Hz, and, even if there are binary AGN candidates, LISA will be the only instrument to observe MBHBs at sub-parsec scale. The promised LISA scientific case for MBHBs is outstanding: scanning the entire Universe with GWs, LISA will be able not only to provide exquisite estimate of the binary parameters such as masses and luminosity distance but especially to shed light on the history merger of MBHBs and on the astrophysical processes driving their evolution. Thanks to the close interplay between MBH and the host galaxy, GWs from MBHBs are an excellence way to investigate their formation and evolution. Moreover, if an electromagnetic (EM) counterpart is emitted together with the GW signal, multimessenger observations of MBHBs are the perfect tools to test the expansion of the Universe and to perform tests of General Relativity.

Data: CORDIS, © European Union