PhD in kinetic theory ANR BEYOND-BL M/F

Job Description

Thesis Subject

Self-gravitating systems are ubiquitous in the Universe. Their long-term relaxation, driven by self-generated perturbations, is described by the inhomogeneous Balescu-Lenard (BL) equation. This kinetic equation is generic, versatile, and extremely rich physically. In particular, BL accounts for inhomogeneity (i.e. intricate stellar orbits), linear amplification (i.e. collective gravitational effects), non-local resonances (i.e. long-range encounters), and orbital diffusion (i.e. dynamical heating). Recent years have shown the prowess of BL in describing the long-term evolution of galactic discs, galactic nuclei or globular clusters.

Yet, BL relies on specific assumptions: (i) a quasilinear assumption (i.e. perturbations must be small); (ii) an ensemble average (i.e. BL only describes the “average” galaxy); (iii) a weak collective amplification (i.e. self-gravitating amplification must be limited); (iv) a smooth interaction potential (i.e. stellar orbits must be quasiperiodic). Of particular interest for this PhD, BL also assumes for the profile of orbital frequencies to be non-singular, i.e. no discontinuities and no lack nor over-abundance of resonances.

This last assumption is where the heart of the present PhD project lies. Its goal is to quantify precisely the role played by resonances during the relaxation of stellar systems. Along these lines, the PhD student will investigate in particular effects associated with (i) resonance broadening; (ii) harmonic relaxation; (iii) branch cuts; (iv) and kinetic blockings. Once completed, this PhD project will have highlighted the key role resonances play during the long-term dynamics of self-gravitating systems.

Your Work Environment

The PhD project will take place at the Paris Institute of Astrophysics, supervised by Jean-Baptiste FOUVRY, and funded by the ANR BEYOND-BL program. The doctoral position will last three years. The contract will begin on October 1st 2026.

Compensation and benefits

Compensation

2300 € gross monthly

Annual leave and RTT

44 jours

Remote Working practice and compensation

Pratique et indemnisation du TT

Transport

Prise en charge à 75% du coût et forfait mobilité durable jusqu’à 300€

About the offer

About the CNRS

The CNRS is a major player in fundamental research on a global scale. The CNRS is the only French organization active in all scientific fields. Its unique position as a multi-specialist allows it to bring together different disciplines to address the most important challenges of the contemporary world, in connection with the actors of change.

CNRS

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