JWST images illuminate ‘black hole stars’ at cosmic dawn

First glimpsed as "little red dots" in deep-space images from the James Webb Space Telescope (JWST), these giant, gas-shrouded black holes have been a hot topic in astrophysics since their discovery in 2022. Each LRD is at least 100,000 times larger than our sun and can be found in almost every survey area of the universe's first 1.5 billion years.

Researchers are now increasingly convinced that LRDs should be renamed "black hole stars." These objects are theorized to be black holes surrounded by and feeding on cocoons of hot, ionized gas, radiating much like stars as they grow. The reddish color comes from the outgoing light being reddened by the surrounding gas. If this hypothesis holds true, LRDs would coincide with the emergence of supermassive black holes at the centers of large galaxies.

A prime example of an early LRD, MoM-BH*-1, was observed 660 million years after the big bang and featured a strong "Balmer break" in its spectrum. This indicates dense, turbulent clouds of hydrogen absorbing higher-energy radiation, a strong indication of a black hole cocooned in gas.

The discovery of black hole stars could help explain the nature of LRDs and provide insights into the formation of the universe's biggest black holes. This finding, published in Nature, may also shed light on the peculiar properties of globular clusters and the early universe's beginnings.