In Brief

What’s up ?

Slides from the talk given at “Pharos Conference 2022” on gravitation available here.

About me

I am an astrophysicist working for the CNRS at Laboratory Universe and Theories (LUTH) of Paris Observatory (Laboratoire Univers et Théorie, Observatoire de Paris). My research focuses on a type of stars called pulsars, which are highly magnetized rotating neutron stars or, more poetically, cosmic lighthouses. I am developing analytical and numerical models in order to enable us to use neutron stars as experimental setups to study extreme physics, from gravitation to ultra-dense matter through quantum electrodynamics.

If you don’t know what pulsars are:

Neutron stars are the collapsed cores of some massive stars after they explode in supernovae, and are the densest astrophysical objects we know of, weighting ~ 1.4 solar masses for a diameter of only ~25km. Had they collapsed further down, they would have formed a black hole, for which the notion of density is no longer defined. On the other hand, their magnetic field can be 100 billion times stronger than the magnetic field of the Earth. This creates an environment, the magnetosphere, in which utterly exotic phenomena can happen, whereby light is transformed into matter and matter into light. In particular, this results in a beam of light above the magnetic poles which, together with the rotation, makes the star appear to pulsate as the light passes on and off our line of sight. The environment of these stars contains physics that cannot be tested in the Solar system, let alone on Earth. Studying them is therefore a unique window on some of the most fundamental aspects of Nature.

I explained pulsars in an outreach video made by Cyril Plou.

My work

I have been working on quantum electrodynamics processes in the magnetosphere, understanding the theory behind light-matter interactions. Using the technique of pulsar timing, I also studied the motion of a pulsar in orbit with other stars, and I obtained with my collaborators one of the most compelling tests of the theory of gravity, general relativity. I have also been working on a type of pulsar nicknamed “Spiders”, where the pulsar is literally evaporating its companion star.

Observatoire de Paris, Université de Recherche PSL