What question did this study set out to answer?

The study aims to analyze the gap rates in stellar streams to assess dark matter subhalo populations.

February 5, 2026Open Access

The Stellar Stream Gap Deficit: Observational Constraints on Dark Matter Subhalo Populations

Key Points

The study aims to analyze the gap rates in stellar streams to assess dark matter subhalo populations.
Systematic analysis of 20 stellar streams across 1308° on the sky
Comparison of observed gap rates to ΛCDM predictions
Statistical analysis accounting for detection incompleteness
Observed gap rate: 0.69 ± 0.23 per 100°
CDM prediction range: 5–15 gaps per 100°
Significant tension of 6σ with a probability of P ≈ 10⁻¹⁰
Deficit favors smoother gravitational theories like warm dark matter

Abstract

A systematic analysis of stellar stream gaps across 20 streams (1308° on sky) revealing a significant deficit compared to ΛCDM predictions. Key findings: Observed gap rate: 0.69 ± 0.23 per 100° CDM prediction: 5–15 per 100° Tension: 6σ (P ≈ 10⁻¹⁰) even after accounting for 50% detection incompleteness The gap deficit favors gravitational theories with smoother potentials, including warm dark matter, self-interacting dark matter, or baryonic-only models. The GD-1 spur is shown to be statistically expected from rare baryonic encounters (P ≈ 70%).

The Stellar Stream Gap Deficit: Observational Constraints on Dark Matter Subhalo Populations

Key Points

Abstract

Cite This Study

Also Consider

Also Consider