What caused a mysterious X-ray flash in a distant star cluster?

A globular cluster harbors a mystery: a brief, intense X-ray flare that doesn't match any known stellar explosion. New deep observations with the Chandra X-ray telescope reveal three faint sources at the flare's location, each a potential culprit. The team considers exotic explanations—light amplified by gravity (microlensing) or activity from a black hole—to account for the unusual brightness and duration.