Crossing the dark matter soliton core: a possible reversed orbital precession

TL;DR

This paper explores how a dark matter soliton core near the Galactic Centre could cause stars' orbital precession to reverse direction, offering a potential test for ultra-light dark matter models.

Contribution

It provides the first theoretical analysis of stellar orbital precession reversal caused by a dark matter soliton core near Sgr A*.

Findings

Some stellar orbits may exhibit retrograde precession due to the soliton core.

Future observations of stars S2, S12, and S4716 can test the ULDM model.

The effect is significant for ULDM particle masses around 10^{-19} to 10^{-17} eV.

Abstract

The ultra-light dark matter (ULDM) model has become a popular dark matter scenario nowadays. The mass of the ULDM particles is extremely small so that they can exhibit wave properties in the central dark matter halo region. Numerical simulations show that a soliton core with an almost constant mass density would be formed inside the ULDM halo. If our Galactic Centre has a dark matter soliton core, some of the stars orbiting about the supermassive black hole (Sgr A*) would be crossing the soliton core boundary. In this article, we report the first theoretical study on how the dark matter soliton core near the Sgr A* could affect the surrounding stellar orbital precession. We show that some particular stellar orbital precession may become retrograde in direction, which is opposite to the prograde direction predicted by General Relativity. We anticipate that future orbital data of the stars S2, S12 and S4716 can provide crucial tests for the ULDM model for $m \sim 10^{-19}-10^{-17}$ eV.