My Research

Primordial Black Holes (PBH), just like regular black holes, are objects that formed when the Universe's local energy density was so high that pressure could not compensate for gravitational pull, leading the matter to collapse. Unlike astrophysical black holes that need a dying star to generate such a high density, PBHs form from overdensities naturally present in the primordial plasma shortly after the Big Bang. These black holes may be as heavy as an asteroid or a star and contribute to the dark matter density today, or they may be very light (even lighter than a gram) and evaporate quickly via Hawking radiation. My job is to predict how many were formed in cosmology and to design ways to prove their existence with observations...

• My PBH works...

Many observations suggest that there is about five times more dark matter in the Universe than ordinary matter. My mission, as a theorist, is to consider various hypotheses regarding the nature of dark matter (is it made of particles? Black holes? Something else?) and propose original ways to test these hypothese with observations and experiments. I am particularly interested in models that go beyond vanilla WIMP models, and the way this dark matter was produced in the early Universe...

• My Dark-Matter related works...

The existence of new particles beyond the standard model of particle physics can have many implications for astrophysics, cosmology, and laboratory search experiments. Neutrinos, dark matter, axions, new particles predicted by supersymmetry and string theory, and many different theories of particle physics predict the existence of such particles. I published many studies on the imprint of astroparticles on observations.

• My astroparticle publications...

Many theories attempting to unify the fundamental forces of our Universe and understand its complex geometry predict the existence of many new particles. In several works, I attempted to find signatures of such theories in primordial cosmology, on the production of dark matter, or even at the LHC.

• My works on Strings, SUSY, SUGRA, etc.

Violent astrophysical events, such as active galactic nuclei, are known to produce particles with an extremely high velocity. When the energy of such particles reach the billion of billion electronVolts, such cosmic ray can produce extensive showers in the Earth atmosphere that can be observed using large-volume detectors such as IceCube, the Pierre Auger Observatory, or, in the future, GRAND, POEMMA, Trinity, etc. Because such cosmic rays can have energies that are much larger than what is accessible in Earth-based experiments, they constitute fantastic cosmic particle accelerators. In a series of works, I proposed to use large-volume detectors to search for the existence of new physics at very high energy.

• My works on ultra-high-energy cosmic rays...

Cosmic microwave background (CMB) observations suggest that the Universe is astonishingly flat and homogeneous, leading the scientific community to believe that the Universe inflated extremely fast immediately after the Big Bang. Cosmic inflation is a theory that is challenging to confirm with observations. One of my primary research goals is to scrutinize the effect of cosmic inflation on cosmological data and attempt to constrain inflation theories with current and future datasets.

• My works on cosmic inflation...

Since the emission of the Cosmic Microwave Background (about 380,000 years after the Big Bang), the evolution of the Universe can be very well described using the ΛCDM model (containing only non-interacting components of dark energy, dark matter, and radiation). However, things were very different in the primordial Universe, especially about the end of cosmic inflation. I explore how different theories, such as string theory, supergravity, models with extra dimensions, or simply toy models going beyond the ΛCDM model, affect the evolution dynamics of the Universe's expansion. My mission is to design ways to discriminate between different theories of the early Universe using cosmological data, such as gravitational-wave detection, large-scale structure surveys, cosmic rays, dark-matter detectors, etc.

• My works on primordial cosmology...