Dwarf Galaxies Imply Dark Matter Is Heavier than 2.2×10^{-21}  eV.

Area of Science:

• Cosmology
• Astrophysics
• Particle Physics

Background:

• A common method to estimate a lower bound for dark matter particle mass (m) involves comparing its de Broglie wavelength to a galaxy's virial radius.
• This approach yields a lower limit of m≳10^{-22} eV for dwarf galaxies, but lacks rigorous derivation.

Purpose of the Study:

• To rigorously derive a lower bound for the dark matter particle mass.
• To test the self-consistency of dark matter models in the local Universe.

Main Methods:

• Utilized stellar kinematical data from the Milky Way satellite galaxy Leo II.
• Reconstructed a statistical ensemble of dark matter wave functions and density profiles.
• Employed a data-driven, model-independent reconstruction and a variant of the maximum mean discrepancy for statistical analysis.

Main Results:

• Determined a lower limit for the dark matter particle mass of m>2.2×10^{-21} eV at >95% confidence level (CL).
• This limit is derived self-consistently for dark matter in the local Universe.

Conclusions:

• The study provides a rigorous, statistically robust lower limit for dark matter particle mass.
• This limit assumes dark matter is primarily a single bosonic particle species, without imposing cosmological, microphysical, or dynamical assumptions.