The Anisotropic Spatial Distribution of Hypervelocity Stars

TL;DR

This paper investigates the spatial distribution of hypervelocity stars, revealing significant anisotropy in their angular positions, which may shed light on their origins and the structure of the galaxy.

Contribution

It provides the first analysis of the anisotropic distribution of unbound hypervelocity stars and discusses implications for their origin and future observational constraints.

Findings

HVSs are spatially anisotropic at 3-sigma level

Anisotropy is significant in Galactic longitude, not latitude

Including lower velocity HVSs reduces anisotropy significance

Abstract

We study the distribution of angular positions and angular separations of unbound hypervelocity stars (HVSs). HVSs are spatially anisotropic at the 3-sigma level. The spatial anisotropy is significant in Galactic longitude, not in latitude, and the inclusion of lower velocity, possibly bound HVSs reduces the significance of the anisotropy. We discuss how the observed distribution of HVSs may be linked to their origin. In the future, measuring the distribution of HVSs in the southern sky will provide additional constraints on the spatial anisotropy and the origin of HVSs.