Résumé / Abstract Seminaire_GReCO
SÉMINAIRE DU GRECO

"Generation of vorticity in our universe: a perturbative approach"

Giulia Cusin
Dept. Physique Théorique, Univ. Genève (Genève, Suisse)

We compute the generation of vorticity from velocity dispersion in the dark matter fluid. If dark matter is described as a perfect fluid at zero temperature, Helmholtz’s theorem dictates that no vorticity is generated. We go beyond this standard description and we allow the dark matter fluid to have a non-vanishing velocity dispersion. This implies a modification to the usual hydrodynamical system (continuity & Euler equations): the Boltzmann hierarchy has to be considered up to the second moment. As a consequence, the Euler equation is modified with a source term that describes the effect of non-zero velocity dispersion. We write an equation for the Eulerian vorticity in Lagrangian coordinates and show that it has a growing mode already at second order in perturbation theory. We compute the power spectrum of the vorticity and of the rotational component of velocity at second order in perturbation theory.

lundi 13 février 2017 - 11:00
Salle des séminaires Évry Schatzman,
Institut d'Astrophysique de Paris

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