27-29 September 2021
Asia/Tokyo timezone

On the Random Motion of Nuclear Objects in a Fuzzy Dark Matter Halo

29 Sep 2021, 11:15




Dhruba Dutta Chowdhury


Fuzzy Dark Matter (FDM), consisting of ultralight bosons (m_b ~ 10^{-22} eV), is an intriguing alternative to Cold Dark Matter. Numerical simulations that solve the Schrodinger-Poisson (SP) equation show that FDM halos consist of a central solitonic core, which is the ground state of the SP equation, surrounded by an envelope of interfering excited states. These excited states also interfere with the soliton, causing it to oscillate and execute a confined random walk with respect to the halo center of mass. Using high-resolution numerical simulations of a 6.6 x 10^{9} M_sun FDM halo with m_b = 8 x 10^{-23} eV in isolation, we demonstrate that the wobbling, oscillating soliton gravitationally perturbs nuclear objects, such as supermassive black holes or dense star clusters, causing them to diffuse outwards. In particular, we show that, on average, objects with mass < 0.3 % of the soliton mass (M_sol) are expelled from the soliton in ~ 3 Gyr, after which they continue their outward diffusion due to gravitational interactions with the soliton and the halo granules. More massive objects (> 1 % M_sol), while executing a random walk, remain largely confined to the soliton due to dynamical friction. We briefly discuss how the observed displacements of star clusters and active galactic nuclei from the centers of their host galaxies can be used to constrain FDM.

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