Are nonsingular black holes with super-Planckian hair ruled out by S2 star data?

TL;DR

This paper introduces a new nonsingular black-hole model with a large 'hair' parameter, which causes observable deviations in star orbits, and uses S2 star data to constrain this parameter, leaving open the possibility of super-Planckian hair.

Contribution

It proposes a novel black-hole spacetime with super-Planckian hair and tests its observational viability using S2 star data around SgrA*.

Findings

Black-hole solutions with large hair are thermodynamically favored in certain parameter ranges.

The model predicts measurable deviations in star orbit precession.

S2 star data constrains the hair parameter to be less than approximately 0.47 times GM.

Abstract

We propose a novel nonsingular black-hole spacetime representing a strong deformation of the Schwarzschild solution with mass $M$ by an additional hair $\ell$, which may be hierarchically larger than the Planck scale. Our black-hole model presents a de Sitter core and $\mathcal{O}(\ell^2/r^2)$ slow-decaying corrections to the Schwarzschild solution. Our black-hole solutions are thermodynamically preferred when $0.2 \lesssim \ell/GM \lesssim \, 0.3$ and are characterized by strong deviations in the orbits of test particles from the Schwarzschild case. In particular, we find corrections to the perihelion precession angle scaling linearly with $\ell$. We test our model using the available data for the orbits of the S2 star around $\text{SgrA}^*$. These data strongly constrain the value of the hair $\ell$, casting an upper bound on it of $\sim \, 0.47 \, GM$, but do not rule out the possible existence of regular black holes with super-Planckian hair.