Galactic discs in Fuzzy Dark Matter haloes

Document Type

Conference Proceeding

Publication Date

7-2022

Abstract

The Cold Dark Matter model encounters well-known problems at the small scales of dark matter haloes (such as the "core-cusp" discrepancy). One way of solving these problems is to investigate dark matter candidates differing from the WIMPs of CDM, with properties adequately affecting the dynamics of dark matter at small-scales. Fuzzy Dark Matter, hereafter FDM, (reviewed in Hui et al. 2017), would consist of ultra-light axions of mass of the order 10‑22 eV with a large de Broglie wavelength for velocities typical of galactic dynamics, which results in the suppression of small-scale structure through large spatial fluctuations in position and finite Bose-Einstein density cores. In El Zant et al 2020, we focused on the impact of force fluctuations due to FDM on stars of galactic discs by developing a theoretical formalism, giving some first constraints on the axion mass. We will present investigations of how this formalism, when applied in numerical simulations, can help quantify the dynamical impact of FDM haloes on stellar discs of Milky Way type galaxies (Halle et al 2022, in prep) and constrain the FDM axion mass. Density fluctuations resulting from the finite de Broglie wavelength of FDM imply force fluctuations applying on classical test particles. Discs are heated by these perturbative forces whose intensity increase when the assumed axion mass decreases. Stellar discs are simulated either in CDM haloes or in FDM haloes with different values of the mass of the axion. For small values of this mass, we observe a thickening of the discs and only very mild non-axisymmetries that are incompatible with observations.

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