space Paradigm Challenge

There are 'imposter' stars out there that cast shadows that look exactly like black holes.

March 19, 2026

Original Paper

The imitation game (r)evolutions: $Q$-star effective shadow from GRMHD analysis

Víctor Jaramillo, Laura Meneses, Héctor R. Olivares Sánchez, Carlos Herdeiro, Darío Núñez, Shuang-Yong Zhou

arXiv · 2603.16995

The Takeaway

Scientists have found that a hypothetical type of stable star made of exotic particles (a Q-star) can create a central 'shadow' nearly identical to a black hole's. This suggests that some of the objects we've identified as black holes in the past might actually be these perfect cosmic mimickers.

From the abstract

$Q$-stars are a class of boson stars arising in scalar-field theories with interacting potentials, minimally coupled to gravity. We show that, in certain regions of parameter space, the angular velocity of stable timelike circular geodesics around $Q$-stars can attain a maximum at a nonzero radius. Notably, this behaviour may occur for stable configurations. This feature has been argued to produce effective shadows, but so far it has only been investigated for unstable solutions. We test this po