Soliton oscillations and revised constraints from Eridanus II of fuzzy dark matter.

Fuzzy dark matter (FDM) has been a promising alternative to standard cold dark matter. The model consists of ultralight bosons with mass mb∼10-22 eV and features a quantum-pressure-supported solitonic core that oscillates. In this work, we show that the soliton density oscillations persist even after significant tidal stripping of the outer halo. We report two intrinsic yet distinct timescales associated, respectively, with the ground-state soliton wave function τ00 and the soliton density oscillations τsoliton, obeying τsoliton/τ00≃2.3. The central star cluster (SC) in Eridanus II has a characteristic timescale τsoliton/τSC∼2-3 that deviates substantially from unity. As a result, we demonstrate, both analytically and numerically with three-dimensional self-consistent FDM simulations, that the gravitational heating of the SC owing to soliton density oscillations is negligible irrespective of mb. We also show that the subhalo mass function to form Eridanus II does not place a strong constraint on mb. These results are contrary to the previous findings by Marsh and Niemeyer (2019). [ABSTRACT FROM AUTHOR]