New simulations suggest the Milky Way could contain a large, mostly unseen population of stellar-mass black holes that do not orbit a companion star. That idea would help explain a long-standing mismatch in astronomy: nearly all known stellar-mass black holes have been detected in binary systems, even though researchers have suspected that many more should exist alone.

The finding points to a likely detection bias rather than proof that binary black holes dominate the galaxy. Black holes paired with another object can be easier to identify because their surroundings may reveal their presence, while isolated black holes are far harder to spot. As a result, current catalogs may reflect what telescopes can detect most readily, not the true balance of black holes in the Milky Way.

By modeling how black holes form and evolve, the simulations indicate that companionless black holes may be common and simply hidden from view. If that picture is correct, the black holes astronomers have already found would represent only a small and unusually visible slice of a much larger galactic population.

The study adds weight to the idea that many stellar-mass black holes are effectively invisible unless researchers develop ways to detect them indirectly. It also highlights how simulations can fill gaps in observations, offering a clearer picture of what may be lurking in the Milky Way beyond the black holes already linked to binary systems.