Gravitationally Focused Dark Matter Around Compact Stars

Abstract

If dark matter self-annihilates then it may produce an observable signal when its density is high. The details depend on the intrinsic properties of dark matter and how it clusters in space. For example, the density profile of some dark matter candidates may rise steeply enough toward the Galactic Center that self-annihilation produces detectable gamma-ray emission. Here, we discuss the possibility that an annihilation signal may arise near a compact object (e.g., neutron star or black hole) even when the density of dark matter in the neighborhood of the object is uniform. Gravitational focusing produces a local enhancement of density, with a profile that falls off approximately as the inverse square-root of distance from the compact star. While geometric dilution may overwhelm the annihilation signal from this local enhancement, magnetic fields tied to the compact object can increase the signal's contrast relative to the background.

ApJS, accepted; 12 pages, 4 figures

References in corpus (5)

• Collisionally Regenerated Dark Matter Structures in Galactic Nuclei
• Challenges in Detecting Gamma-Rays From Dark Matter Annihilations in the Galactic Center
• Phase-space distribution of unbound dark matter near the Sun
• Probing dark matter models with neutrinos from the Galactic center
• Gamma-Ray Constraints on the First Stars from Annihilation of Light WIMPs

Cited by in corpus (4)

• Effects of fermionic dark matter on properties of neutron stars
• Neutrino Oscillations as a Probe of Light Scalar Dark Matter
• Exact expressions for the pericenter precession caused by some Dark Matter distributions and constraints on them from orbital motions in the Solar System, in the double pulsar and in the Galactic center
• Universal Density and Velocity Distributions of Dark Matter around Massive Black Holes