Scientists finally know what the mysterious ‘little red dots’ throughout the universe are

Scientists finally know what the mysterious “little red dots” spread throughout the universe are.

At the end of 2021, when Nasa’s James Webb Space Telescope switched on, scientists noticed that there were unexplained red dots seen in its images, among the normal stars and galaxie. In the years since, they have mystified researchers who were unable to explain the phenomenon.

It became even more mysterious as researchers realised that the red dots came from near the beginning of the universe, when it was only a few hundred million years old. A billion years later, they disappear.

Now, researchers believe they have an explanation: they are a cocoon of ionised gas, hiding the most violent forces in the universe behind them.

The red dots are young black holes, they say. They are some of the smallest ever found – though they still have the mass of 10 million of our Suns.

"The little red dots are young black holes, a hundred times less massive than previously believed, enshrouded in a cocoon of gas, which they are consuming in order to grow larger. This process generates enormous heat, which shines through the cocoon. This radiation through the cocoon is what gives little red dots their unique red colour," said Darach Watson, who helped to lead the research.

‘“They are far less massive than people previously believed, so we do not need to invoke completely new types of events to explain them.”

The light that we can see is produced as gas falls into the black hole, heating it up and shining the light that we can see through our telescopes.

"When gas falls towards a black hole, it spirals down into a kind of disk or funnel towards surface of the black hole,” said Professor Watson. “It ends up going so fast and is squeezed so densely that it generates temperatures of millions of degrees and lights up brightly.

“But only a very small amount of the gas is swallowed by the black hole. Most of it is blown back out from the poles as the black hole rotates. That's why we call black holes ‘messy eaters’.”

The work is reported in a new paper, ‘Little red dots as young supermassive black holes in dense ionized cocoons’, published in the journal Nature.