• Welcome
• Member groups
• Events
• Projects
• Board

29. November 2022 14:15

Coherent and incoherent structures in fuzzy dark matter halos

I-Kang Liu
Newcastle University, Newcastle upon Tyne, England

Dark matter(DM) halos composed of ultralight bosons exhibit wavy behaviour with de Broglie wavelength in cosmological scales, known as fuzzy DM (FDM), wave DM or BECDM. To the leading order of the space-time metric, the effective equation of motion is the Schrodinger-Poison system of equation, a classical-field wavefunction coupled to Newtonian gravity, and is reminiscent of the universal phenomenon of Bose-Einstein condensation (BEC), described by a macroscopic condensate wavefunction. This model reproduces the density distribution in large length scales in the cold DM model, called Navarro–Frenk–White profile, and can be a candidate to resolve the missing-satellite, too-big-to-fail and cusp-core problems with a compact solitonic core in the centre of a halo. Here inspired by widely-studied laboratory atomic systems we systematically examine the BEC concept by examining the field fluctuations in fuzzy dark matter halos, generated by our merger simulations, via probing the spatial phase-phase and density-density correlation functions to unveil the FDM halo properties. We find out that the solitonic core is fully coherent and coincides with the Penrose-Onsager condensate mode, exhibiting off-diagonal-long-range order, of a virialized halo. Moving outward from the core, fluctuations enhance and the bimodal fit of the core-halo profile can nicely capture the crossover length scale. By looking at the energy distribution, we demonstrate that these fluctuations are mainly sourced by a large number of quantized vortices, indicating a turbulence-like state, which is persistent in our simulation. In addition, the intervortex distance scale matches the granule one by comparing the vortex energy and overdensity power spectra. This work provides a new picture to investigate the FDM halos.