Institute of research into the fundamental laws of the Universe

Core-collapse supernovae play a crucial role in the stellar evolution of massive stars, the birth of neutron stars and black holes, and the chemical enrichment of galaxies. How do they explode? The explosion mechanism can be revealed by the analysis of multi-messenger signals: the production of neutrinos and gravitational waves is modulated by hydrodynamic instabilities during the second following the formation of a proto-neutron star.
This thesis proposes to use the complementarity of multi-messenger signals, using numerical simulations of the stellar core- collapse and perturbative analysis, in order to extract physical information on the explosion mechanism.
The project will particularly focus on the multi-messenger properties of the stationary shock instability (SASI) and the corotational instability (low T/W) for a rotating progenitor. For each of these instabilities, the signal from different species of neutrinos and the gravitational waves with different polarization will be exploited, as well as the correlation between them.

Planet formation is a key topic of modern astrophysics with implications on existential questions such as the origin of life in the Universe. Quite surprisingly, we do not precisely know when and where planets are formed in protoplanetary disks. Recent observations however indicate that this might happen sooner than we previously believed. But the physical conditions in the young disks remain poorly constrained. During this thesis we propose to test the hypothesis that planets could form early. We will perform 3D simulations of protoplanetary disk formation with gas, dust and including the mechanisms of planetesimal formation. In addition from determining whether planets form early we will be able to predict the architectures of exoplanet systems and to compare them to real ones. This work, beyond the current state-of-the-art, is timely as many efforts are currently being done by our community to better understand exoplanets as well as our origins.