Using the motion of S2 to constrain scalar clouds around SgrA*

TL;DR

This study uses precise measurements of star S2's orbit around SgrA* to search for and constrain the presence of ultralight scalar field dark matter clouds, finding no significant evidence but setting strict upper limits.

Contribution

It introduces a novel application of orbital data to constrain scalar field dark matter structures around a supermassive black hole.

Findings

No substantial evidence for scalar clouds around SgrA*

Constraints limit scalar cloud mass to less than 0.1% of SgrA*'s mass

Sets strong bounds on ultralight scalar field dark matter in galactic centers

Abstract

The motion of S2, one of the stars closest to the Galactic Centre, has been measured accurately and used to study the compact object at the centre of the Milky Way. It is commonly accepted that this object is a supermassive black hole but the nature of its environment is open to discussion. Here, we investigate the possibility that dark matter in the form of an ultralight scalar field ``cloud'' clusters around Sgr~A*. We use the available data for S2 to perform a Markov Chain Monte Carlo analysis and find the best-fit estimates for a scalar cloud structure. Our results show no substantial evidence for such structures. When the cloud size is of the order of the size of the orbit of S2, we are able to constrain its mass to be smaller than $0.1\%$ of the central mass, setting a strong bound on the presence of new fields in the galactic centre.