Early Universe’s supermassive black holes grew in cocoons like butterflies

When the James Webb Space Telescope sent its first high-definition infrared images back to Earth, astronomers noticed several tiny, glowing, crimson stains. These objects, quickly named “Little Red Dots,” were too bright to be normal galaxies, and too red to be simple star clusters. They appeared to house supermassive black holes that were far more massive than they had any right to be.

But now a new study published in Nature suggests a solution to the Little Red Dots mystery. Scientists think young supermassive black holes may go through a “cocoon phase,” where they grow surrounded by high-density gas they feed on. These gaseous cocoons are likely what the JWST saw as the Little Red Dots.

The overmassive black hole problem

The first explanation scientists had for the Little Red Dots was that they were compact, distant galaxies, but something felt off about them right from the start. “They were too massive, since we saw they’d have to be completely filled with stars,” says Vadim Rusakov, an astronomer at the University of Manchester and lead author of the study. “They would need to produce stars at 100 percent efficiency, and that’s not what we’re used to seeing. Galaxies cannot produce stars at more than 20 percent efficiency, at least that’s what our current knowledge is.”

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