Speaker
Description
Considering the self-interaction of bosonic scalar Ultra-Light Dark Matter (ULDM) relaxes the constraints on its particle mass, typically estimated to be around ~1e−22 eV. We calculate the dynamical friction (DF) coefficient for a steady-state circular orbit induced by the gravitational wake of ULDM using multipole expansion. In the strong self-coupling regime, the leading-order term for the Mach number, only arising in the dipole term (l=1), closely matches the full-order calculation. Applying these findings to the Fornax dwarf spheroidal galaxy (dSph) and its globular clusters (GCs), and assuming a DM halo density profile in the Thomas-Fermi limit, we provide a plausible explanation for the extended lifetime of Fornax GCs. Furthermore, considering self-interaction can reduce the DF force, and further increases their lifetime.
