Soliton Oscillations and Revised Constraints from Eridanus II of Fuzzy Dark Matter

Barry T. Chiang; Hsi-Yu Schive; Tzihong Chiueh

doi:10.1103/PhysRevD.103.103019

paper

Soliton Oscillations and Revised Constraints from Eridanus II of Fuzzy Dark Matter

arXiv:2104.13359 · doi:10.1103/PhysRevD.103.103019

Abstract

Fuzzy dark matter (FDM) has been a promising alternative to standard cold dark matter. The model consists of ultralight bosons with mass $m_{b} \sim 1 0^{- 22}$ 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 wavefunction $τ_{00}$ and the soliton density oscillations $τ_{soliton}$ , obeying $τ_{soliton} / τ_{00} ≃ 2.3$ . The central star cluster (SC) in Eridanus II has a characteristic timescale $τ_{soliton} / τ_{SC} \sim 2$ to $3$ 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 $m_{b}$ . We also show that the subhalo mass function to form Eridanus II does not place a strong constraint on $m_{b}$ . These results are contrary to the previous findings by Marsh & Niemeyer (2019).

arXiv comment19 pages, 19 figures; Accepted for publication in PRD

Soliton Oscillations and Revised Constraints from Eridanus II of Fuzzy Dark Matter

Abstract

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