Erlangen 2026 – scientific programme

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GR: Fachverband Gravitation, Relativistische Astrophysik und Kosmologie

GR 17: Cosmology II

GR 17.2: Talk

Friday, March 20, 2026, 09:30–09:45, KH 01.016

Early growth of structure with warm wave dark matter — •Simon May — Universität Bielefeld, Universitätsstraße 25, 33615 Bielefeld, Germany

I will present unique features in the growth of structure in wave dark matter models with warm white noise, where the power spectrum is peaked at sub-horizon wavenumbers. The post-inflationary production of bosonic particles, such as axions or axion-like particles, leads to an enhanced isocurvature density power spectrum on small scales. Moreover, when dark matter is extremely light, these inhomogeneities result in a non-negligible velocity dispersion and hence free-streaming suppression of the adiabatic power spectrum. Starting with the Schrödinger--Poisson system of equations as the relevant equations of motion, I will present results from analytic calculations and numerical simulations of cosmic structure formation. The results show the enhancement and evolution of the small-scale power spectrum and the formation of non-linear collapsed objects, including wave dark matter halos and Bose stars (solitons), shortly after matter--radiation equality. Using hydrodynamical simulations of warm wave dark matter with baryons, I will further show how this affects the early clustering of baryonic matter. Probes of the small-scale power spectrum (e.g. dynamical heating of stars, Ly-α forest, gravitational lensing, 21cm-line intensity mapping) can be sensitive to these effects on quasi-linear scales, making this broad class of dark matter models accessible to observations.

Keywords: dark matter; structure formation; numerical simulations