Dwarf spheroidal J-factors without priors: A likelihood-based analysis for indirect dark matter searches

Understand

Line-of-sight integrals of the squared density, commonly called the J-factor, are essential for inferring dark matter annihilation signals.

• The J-factors of dark matter-dominated dwarf spheroidal satellite galaxies (dSphs) have typically been derived using Bayesian techniques, which for small data samples implies that a choice of priors constitutes a non-negligible systematic uncertainty.
• Here we report the development of a new fully frequentist approach to construct the profile likelihood of the J-factor.
• Using stellar kinematic data from several classical and ultra-faint dSphs, we derive the maximum likelihood value for the J-factor and its confidence intervals.