Mysterious “little red dots” could be black holes in disguise

The universe has a habit of playing tricks on astronomers. In the 1960s, the sky was found to be full of strange “little blue stars” that appear to belong to the Milky Way constellations, but are actually quasars: supermassive black holes outside the galaxy. In 2022, astronomers face a new mystery: “little red dots” (LRDs). These points of light – like their blue predecessors – are compact, bright and mystifying. LRDs have sparked intense debate over whether they are young, unexpectedly star-filled galaxies or unnaturally massive black holes accumulating glowing gas. Write in natureRusakov et al.¹ He reports an analysis of the light from LRDs that supports the latter scenario but suggests that the black holes are hidden behind a thick curtain of gas, which made them appear more massive in previous analyzes than they actually are.