Constraints on self-interacting Bose-Einstein condensate dark matter using large-scale observables

TL;DR

This study uses large-scale cosmological observations to constrain self-interacting Bose-Einstein condensed dark matter models, finding that certain interaction strengths are excluded unless specific transition scenarios are assumed.

Contribution

It provides new constraints on SIBEC-DM models using multiple cosmological datasets, especially ruling out strong self-interactions in the simplest scenario.

Findings

Pure SIBEC-DM with strong self-interaction is excluded at 98.5% confidence.

Transitions from initial states can relax constraints on self-interaction.

Transitions are favored to occur after matter-radiation equality and start from cold initial states.

Abstract

Constraints on the cosmic history of self-interacting Bose-Einstein condensed (SIBEC) dark matter (DM) are obtained using the cosmic microwave background (CMB), baryonic acoustic oscillations (BAO), growth factor measurements, and type Ia supernovae (SNIa) distances. Four scenarios are considered, one with purely SIBEC-DM, and three in which SIBEC-DM is the final product of some transition from different initial states, which are either cold, warm, or has a constant equation of state. Using a fluid approximation for the self-interacting scalar field it is found that in the simplest scenario of purely SIBEC-DM the self-interaction necessary for solving the cusp-core problem, with core-radii of low-mass halos of order $R_c\gtrsim 1\text{kpc}$, is excluded at $2.4\sigma$, or $98.5\%$ confidence. Introducing a transition, however, relaxes this constraint, but the transitions are preferred to be after matter-radiation equality, and the initial phase to be cold.