韦布望远镜拍到的小红点：是黑洞，还是黑洞星？

Astronomers have encountered something inexplicable: hundreds of small, red dots.

The James Webb Space Telescope began sending back images in 2022, and these dots were in them.

They are absurdly small, less than one percent of the Milky Way's width.

The light comes from 13.4 billion years ago, when the universe was only 500 million years old.

At first, everyone thought these were very crowded, mature galaxies.

Some called them 'universe breakers' because galaxies this early wouldn't have had time to grow.

In 2023, Dale Kocevski of Colby College discovered a strange pattern in the light.

The pattern points to a very dense, rapidly moving cloud of hydrogen gas.

To make hydrogen gas move that fast, an enormous mass must be squeezed into a tiny space.

Kocevski believes only a black hole could do it.

According to him, these dots are black holes at the centers of galaxies, greedily devouring matter.

Such black holes are usually surrounded by a ring of dust, but the red dots are wrapped in a layer of gas that tints the light red.

The trouble is, these dots emit almost no X-rays.

A black hole that is devouring matter should emit very strong X-rays.

Kocevski explains that matter falls in too fast, which instead traps the X-rays inside.

Rohan Naidu of the University of Hawaii proposed a completely different idea.

He says the glow might come from the thicker, denser layer of gas outside the black hole.

The black hole inside heats the gas, and the outermost layer lights up, like the red surface of a star.

They named this idea a 'black-hole star,' and Naidu says it is a completely new kind of celestial object.

People on both sides object, and their reasons are very specific.

Opponents of the 'black-hole star' point out that light from several dots clearly leaks out.

Such thick gas should not let light escape.

The criticism of the black hole model is that it relies on one assumption after another to hold up.

In May of this year, a team measured the mass of one of the red dots for the first time.

The study was led by Ignas Juodžbalis, then at the University of Cambridge.

The result is about tens of millions of times the mass of the Sun, which favors the black hole camp.

But Jenny Greene of Princeton University doubts this measurement method.

She believes this method only works for objects with clear boundaries, like two stars.

The motion inside the red dot occurs in a chaotic cloud of gas, which is very hard to read this way.

Greene put it bluntly: people often see what they want to see.

Juodžbalis also admits that this is just one data point.

So what the red dots actually are still has no answer.

This question involves the universe's earliest batch of supermassive black holes.

Why they could grow so fast—the answer lies in these red dots.