Speaker
Description
We investigate the impact of repulsive self-interaction in ultralight dark matter (ULDM)on dynamical friction in circular orbits in ULDM halos and its implications for the Fornax dwarfspheroidal (dSph) galaxy's globular clusters. Using the Gross-Pitaevskii-Poisson equations, wederive the dynamical friction force considering soliton density profiles for both non-interactingand strongly self-interacting ULDM. Our results show that self-interactions reduce the dynamicalfriction effect further than both the non-interacting ULDM and standard cold dark matter models.Furthermore, we derive the low Mach number approximation to simplify the analysis in the subsonicmotion, where the tangential component of dynamical friction dominates. Applying these findingsto the Fornax dSph, we calculate the infall timescales of globular clusters, demonstrating thatstrong self-interaction can address the timing problem more effectively. We constrain theparameter space for ULDM particle mass and self-coupling constant, which are consistent with otherconstraints from astronomical and cosmological observations. This talk is based on my recent paper (arXiv:2504.19219) published in JCAP.
