Glowing light inside a black hole shadow suggests the object has no event horizon at all.
April 20, 2026
Original Paper
GRMHD accretion beyond the black hole paradigm: Light from within the shadow
arXiv · 2604.15430
The Takeaway
Black holes are defined by an event horizon, a point of no return where light cannot escape, creating a dark shadow in images. New simulations of horizonless singularities show that these mimicker objects can produce almost identical accretion patterns to real black holes. The key difference is a faint, detectable brightness inside the shadow that should be pitch black. If these objects exist, it would mean the famous images from the Event Horizon Telescope might not be showing black holes. This discovery forces astronomers to re-evaluate how they prove the existence of event horizons in the distant universe. It suggests that some of the most massive objects in space might be even weirder than we thought.
From the abstract
We present the first three-dimensional general relativistic magnetohydrodynamic simulation of sustained accretion onto a horizonless singularity in which matter reaches the central object rather than being accumulated outside of it or expelled in outflows. We consider a Joshi-Malafarina-Narayan (JMN-1) spacetime, a well-motivated black hole mimicker that arises from gravitational collapse with anisotropic pressure in general relativity, and adopt a compactness parameter for which the central sin