Carsten Littek

Carsten Littek (Germany)

littek @ uni-heidelberg.de

Cosmological velocity spectra and the laminar-turbulent transition

Starting from the Hamiltonian trajectories of classical particles Bartelmann et al. (2014) have derived a generating functional for a canonical ensemble of initially correlated microscopic particles in the context of cosmological structure formation. This approach is based on the non-equilibrium statistical field theory for classical particles introduced by Mazenko (2010) and Das & Mazenko (2012). The free generating functional
is completely specified by the initial power spectrum and the equations of motion for classical particles. Interactions may be switched on just as in quantum field theory by applying an interaction operator to the free generating functional. Collective properties of the ensemble, such as density and velocity fields, can be derived by taking functional derivatives with respect to the respective source fields.
In this work we aim at understanding the origins of the probability distribution function of the cosmological density field, which simulations suggest to be in good agreement with a log-normal distribution. We also examine the properties of the velocity field of such ensembles in two different physical systems: 1) in cosmological structure formation knowledge of the velocity spectra can help to understand distortions in redshift-space and the kinematic Sunyaev-Zel'dovich effect, 2) in viscous hydrodynamics velocity spectra can help distinguish laminar from turbulent  ows,  thus enabling the investigation of the laminar-turbulent transition.

Supervisor: Matthias Bartelmann (ITA)

 
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