Burkert, A.
(2020):
Fuzzy Dark Matter and Dark Matter Halo Cores.
In: Astrophysical Journal, Vol. 904, No. 2, 161

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Abstract
Whereas cold dark matter (CDM) simulations predict central dark matter cusps with densities that diverge as rho(r) similar to 1/r, observations often indicate constantdensity cores with finite central densities rho(0) and a flat density distribution within a core radius r(0). This paper investigates whether this corecusp problem can be solved by fuzzy dark matter (FDM), a hypothetical particle with a mass of the order of m approximate to 10(22) eV and a corresponding de Broglie wavelength on astrophysical scales. We show that galaxies with CDM halo virial masses Mvir <= 10(11) Mcircle dot follow two corescaling relations. In addition to the wellknown universal core column density Sigma(0) equivalent to rho(0) x r(0) = 75 Mcircle dot pc(2), core radii increase with virial masses as r(0) similar to Mvir(gamma) with gamma of order unity. Using the simulations by Schive et al. we demonstrate that FDM can explain the r(0)Mvir scaling relation if the virial masses of the observed galaxy sample scale with the formation redshift z as Mvir similar to (1 + z)(0.4). The observed constant Sigma(0) is however in complete disagreement with FDM cores which are characterized by a steep dependence Sigma(0) similar to r(0)(3), independent of z. More highresolution simulations are now required to confirm the simulations of Schive et al. and explore the transition region between the soliton core and the surrounding halo. If these results hold, FDM can be ruled out as the origin of observed dark matter cores and other physical processes are required to account for their formation.