Hinting a dark matter nature of Sgr A* via the S-stars

TL;DR

This paper suggests that the orbits of S-stars around the Galactic center are better explained by a dark matter core of fermions called darkinos, challenging the traditional black hole model of Sgr A* and providing an alternative explanation consistent with observed data.

Contribution

It extends previous work by analyzing 17 S-star orbits, supporting the darkino core model as an alternative to the black hole hypothesis for Sgr A*.

Findings

S-star orbits fit better with a darkino core model than a black hole.

The darkino model explains both S-star dynamics and Galactic rotation curves.

Supports the dark matter core hypothesis as an alternative to the black hole model.

Abstract

The motion data of the S-stars around the Galactic center gathered in the last 28 yr imply that Sgr A* hosts a supermassive compact object of about $4\times 10^6$ $M\odot$, a result awarded with the Nobel Prize in Physics 2020. A non-rotating black hole (BH) nature of Sgr A* has been uncritically adopted since the S-star orbits agree with Schwarzschild geometry geodesics. The orbit of S2 has served as a test of General Relativity predictions such as the gravitational redshift and the relativistic precession. The central BH model is, however, challenged by the G2 post-peripassage motion and by the lack of observations on event-horizon-scale distances robustly pointing to its univocal presence. We have recently shown that the S2 and G2 astrometry data are better fitted by geodesics in the spacetime of a self-gravitating dark matter (DM) core - halo distribution of 56 keV-fermions, "darkinos", which also explains the outer halo Galactic rotation curves. This Letter confirms and extends this conclusion using the astrometry data of the $17$ best-resolved S-stars, thereby strengthening the alternative nature of Sgr A* as a dense core of darkinos.