Ultra-Light Dark Matter as a Bose-Einstein Condensate: Galactic-Scale Quantum Effects

Abstract

Ultra-Light Dark Matter (ULDM) composed of extremely light bosonic particles presents a promising alternative to Cold Dark Matter for addressing small-scale structure formation challenges. This study investigates the theoretical framework for ULDM as a galactic-scale Bose-Einstein condensate, with emphasis on quantum effects manifesting at astronomical scales. The research employs theoretical analysis of the Schrödinger-Poisson system, examination of numerical simulation results, and comparison with observational constraints from dwarf galaxy dynamics, gravitational lensing, and large-scale structure observations. Key findings demonstrate that quantum pressure effects naturally produce flat-cored density profiles in galactic centers, resolving the core-cusp problem without requiring additional feedback mechanisms. The wave nature of ULDM creates characteristic suppression in small-scale structure formation, reducing predicted satellite galaxy numbers to match Local Group observations. However, observational constraints from the Lyman-α forest impose stringent lower bounds on particle masses ( m > 2.3×10−21eV ) that create tension with the optimal mass range ( m ~ 10−22eV ) for addressing galactic-scale problems. Numerical simulations reveal computational challenges in resolving quantum wavelengths while environmental effects significantly modify idealized theoretical predictions. The study concludes that while ULDM provides intrinsic quantum solutions to small-scale structure problems, reconciling galactic dynamics with large-scale constraints remains a fundamental challenge requiring refined theoretical models and advanced observational strategies.