Oral Presentation
How do stars affect ψDM haloes?
Presenter: James Chan (EPFL)
Wave dark matter (ψDM) predicts a compact soliton core and a granular halo in every galaxy. This work presents the first simulation study of an elliptical galaxy by including both stars and ψDM, focusing on the systematic changes of the central soliton and halo granules. With the addition of stars in the inner halo, we find that the soliton core consistently becomes more prominent by absorbing mass from the host halo than that without stars, and the halo granules become `non-isothermal', `hotter' in the inner halo, and `cooler' in the outer halo, as opposed to the isothermal halo in pure ψDM cosmological simulations. Moreover, the composite (star+ψDM) mass density is found to follow an r^-2 isothermal profile near the half-light radius in most cases. Most striking is the velocity dispersion of halo stars that increases rapidly towards the galactic centre by a factor of at least 2 inside the half-light radius caused by the deepened soliton gravitational potential, a result that compares favourably with observations of elliptical galaxies and bulges in spiral galaxies. However, in some rare situations, we find a phase segregation turning a compact distribution of stars into two distinct populations with high- and very low-velocity dispersions, while the high-velocity component mostly resides in the halo, the very low-velocity component is bound to the interior of the soliton core, resembling stars in faint dwarf spheroidal galaxies.
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