Capturing the complexity of the cosmic large-scale structure in one wavefunction

Cora Uhlemann, Newcastle University
Friday, November 11, 2022 - 14:00 to 15:00
Hall A, North Campus, Maynooth University

On large scales, the dark matter distribution can be treated as a perfect fluid. On small scales, gravitationally bound structures form through nonlinear clustering. Capturing the resulting cascade of multiple fluid streams in 6d phase space is challenging. Linking cosmology to ideas from different areas of theoretical physics, we suggest approximating the time evolution of the phase-space distribution using a wavefunction in the spirit of the quantum-classical correspondence. In this framework, one can solve a nonlinear Schroedinger equation in 3d position space, where the small parameter hbar acts as a resolution scale. Our method is a tool to describe phase-space dynamics of cold dark matter with wave mechanics in position-space, and the fundamental description for wavelike dark matter such as ultralight particles. With a simple dynamical model for the evolution of the dark matter wavefunction, we demonstrate how wave interference causes large density oscillations on small scales and manifests in vortices with a vanishing density and a localised circulation of velocity. Together with the wave imprint on substructures that leads to exciting and varied probing mechanisms for the nature of dark matter.

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