Astrophysique à Haute Energie

Supermassive black holes (SMBHs) located at the center of galaxies, particularly those powering luminous Active Galactic Nuclei (AGNs), and stellar-mass black holes in X-ray bright binary systems (XRBs), exhibit highly variable and often transient X-ray and gamma-ray emissions. Additionally, Tidal Disruption Events (TDEs) —which occur when a star approaches a massive black hole and is tidally disrupted— produce electromagnetic ares peaking in the UV and soft X-rays. 

The origin of cosmic rays (CRs) with up to 10^20 eV energies is one of the most important questions in astrophysics to date. One way to track down CR sources and study CR propagation is to look for the products of cosmic ray interactions, in particular gamma rays and high-energy (TeV-PeV) neutrinos. The neutrinos, indeed, are characteristic of hadronic interactions and thus would be an unambiguous signature of the presence of cosmic rays. The detection of coincident neutrino and photon signals would allow locating and characterizing CR interaction sites.

The origin of cosmic-rays remains one of the most important open questions in astrophysics. A powerful tool to study their acceleration sites are multi-messenger (photons and neutrinos) observations: wherever a cosmic-ray (a proton or an atomic nucleus) is accelerated, it interacts with its environment producing pions that then decay into photons, neutrinos and electrons.  γ and ν can escape the region and travel on geodesics to Earth, pinpointing their source in the Universe. 

The Astroparticle physics groups hosted at the Centre for Cosmology, Particle Physics and Phenomenology (CP3) at UCLouvain (Belgium) and at the Laboratoire Astroparticule et Cosmologie (APC) at Université Paris Cité (UPCité) are welcoming applications for a joint PhD student position in neutrino and multi-messenger astronomy.