Testing the Prediction of Fuzzy Dark Matter Theory in the Milky Way Center

Zhi 智 Li 李,Hsi-Yu 熙于 Schive 薛,Juntai 俊太 Shen 沈

doi:10.3847/1538-4357/ab6598

Abstract

Abstract The fuzzy dark matter model (FDM; also known as quantum wave dark matter model) argues that light bosons with a mass of are a possible candidate for dark matter in the universe. One of the most important predictions of FDM is the formation of a soliton core instead of a density cusp at the center of galaxies. If FDM is the correct theory of dark matter, then the predicted soliton core can help form the Central Molecular Zone (CMZ) in the Milky Way. We present high-resolution hydrodynamical simulations of gas flow patterns to constrain the properties of the soliton core based on a realistic Milky Way potential. We find that a dense center is required to form a reasonable CMZ. The size and kinematics of the CMZ offer a relatively strong constraint on the inner enclosed mass profile of the Galaxy. If a soliton core is not considered, a compact nuclear bulge alone with a radially varying mass-to-light ratio can match the observed size and kinematics of the CMZ. A soliton core model with a mass of and a core radius of , together with a less massive nuclear bulge with a constant mass-to-light ratio, also agrees nicely with the current data. Such an FDM soliton core corresponds to a boson mass of , which could be further constrained by the improved determination of the mass-to-light ratio in the Galactic center.

Highlights

The current cold dark matter (CDM) model successfully explains many problems on the large-scale structures of the universe (e.g. Frenk & White 2012; Bennett et al 2013), some of its predictions on the galactic scales are still in tension with modern observations
As we have shown in §2.1.2, An assumed a mass-tolight ratio Υ = 2 gives a nuclear bulge mass of 1.4 × 109 M, which is very close to the maximum mass of the soliton core Msmax = 1.44 × 109 M with m22 = 1
The observed size and kinematics of the Central Molecular Zone (CMZ) could be reproduced by including a compact central mass component, whose mass profile is relatively well-constrained by our models

Summary

Introduction

The current cold dark matter (CDM) model successfully explains many problems on the large-scale structures of the universe (e.g. Frenk & White 2012; Bennett et al 2013), some of its predictions on the galactic scales are still in tension with modern observations (see the review by Bullock & Boylan-Kolchin 2017). In recent years the Fuzzy Dark Matter model (FDM), known as “quantum wave dark matter” model, is gaining more attention In this scenario, the dark matter is composed of very light bosons with a particle mass of ∼ 10−22 eV The core radius is usually comparable to the characteristic wavelength, and the halo transitions to a NFW profile within a few core radii according to recent numerical simulations (e.g. Schive et al 2014b). This may provide a plausible solution to the “cusp-core” problem in CDM model.

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Results

Conclusion