Back in 2022, astronomers were puzzled by a so-called “tidal disruption event” (TDE), dubbed AT2018hyz, that had faded when it was first noticed three years earlier, only to unexpectedly reanimate and burp out extremely bright radio waves. University of Oregon astrophysicist Yvette Cendes, a co-author of that 2022 paper, dubbed the black hole “Jetty McJetface” (a nod to the 2016 online British competition to name a research vessel Boaty McBoatface).

Astronomers have continued to monitor it ever since. Far from fading again, the TDE has grown 50 times brighter, and that brightness continues to increase. The black hole's energy emission might not peak until 2027, according to a new paper published in the Astrophysical Journal.

As we've previously discussed, it’s a popular misconception that black holes behave like cosmic vacuum cleaners, ravenously sucking up any matter in their surroundings. In reality, only stuff that passes beyond the event horizon—including light—is swallowed up and can’t escape, although black holes are also messy eaters. That means that part of an object’s matter is actually ejected out in a powerful jet.

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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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