Stellar Mimicry: Boson Stars Pretend to Be Black Holes ✦

Original: "Bayesian Analysis of Massive Boson Star Models for Sagittarius A* Using Near-Infrared Astrometry Data"

· Xiangyu Wang, Tian-chi Ma, Minyong Guo, Hai-Qing Zhang

arXiv:2605.09521v1 · 2026-05-10 · CC BY · ⏱ 1 min · High Energy General Relativity

Bayesian analysis from GRAVITY sees no difference: at the Galactic center, perhaps it's not a hole hiding but its ghostly double.

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Sagittarius A* — not a black hole, but a bosonic mimic? Bayesian analysis by GRAVITY can't tell them apart. Like a harmless fly mimicking a wasp, the object masquerades, but without a horizon — only a cloud of axions. Dark matter steps out of the shadows: if many such stars exist, it's not background, it's the main actor.

🎯 The radius of a boson star can be just 2.81 times the gravitational radius — practically like a black hole, a difference of a fraction of a percent. But unlike one, passing photons do not disappear, but retain information about the internal structure, as if passing through a transparent dream.

ds^2 = -A(r) dt^2 + B(r)^{-1} dr^2 + r^2 (d\theta^2 + \sin^2\theta d\phi^2)

Unlike a black hole, there is no event horizon here — the metric functions A and B are finite everywhere.

Z = \int_{\Omega_\Theta} \mathcal{L}(\Theta) \pi(\Theta) d\Theta

Integral of likelihood over prior distribution, a quantitative measure of how well the model explains the data.

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Stellar Mimicry: Boson Stars Pretend to Be Black Holes ✦