Astronomers have discovered the oldest and most distant black hole — a behemoth that likely formed at the dawn of the universe, more than 13 billion years ago.
The black hole lies at the center of a galaxy known as CAPERS-LRD-z9. Both cosmic objects are thought to have formed around 13.3 billion years ago, or just 500 million years after the big bang that created the universe. (The big bang theory suggests the universe started as an ultradense, extremely hot point that rapidly expanded out in all directions in a chaotic event some 13.8 billion years ago.)
The black hole discovery, described in a study published Wednesday in The Astrophysical Journal Letters, could shed light on the universe’s earliest days and provide insight into how black holes and galaxies evolved.
Light takes time to travel across space, which means observing distant objects in the cosmos is a bit like accessing a portal back in time, said Anthony Taylor, a postdoctoral researcher at the University of Texas at Austin who led the study’s international team of scientists.
“When we look at objects that are very, very far away, it has taken that light billions upon billions of years to reach us,” he said. “So in reality, we’re seeing these objects as they were in the early universe.”
As far as black holes go, this one is huge, according to the researchers. It’s estimated to be up to 300 million times the size of the sun, with a mass equivalent to that of half the stars in its galaxy.
It’s also roughly 10 times more massive than the supermassive black hole at the center of our Milky Way galaxy, Taylor said.
Taylor and his colleagues found the black hole in observations of the outermost reaches of the universe from NASA’s James Webb Space Telescope. The researchers used a technique known as spectroscopy, which splits light into different wavelengths and colors, similar to how a prism separates sunlight into the colors of the rainbow.
With spectroscopy, astronomers can look for telltale signs of stars, galaxies and other celestial objects. Black holes gobble up dust and matter around them, compressing and heating the material as it swirls around and falls into the black hole. All of that can be seen with spectroscopy, said study co-author Steven Finkelstein, a professor of astronomy at the University of Texas at Austin.
“We look for these signatures of very fast-moving gas,” Finkelstein said. “We’re talking about velocities of 1,000, 2,000, sometimes even 3,000 kilometers per second. Nothing else in the universe moves that fast, so we know it has to be gas around a black hole.”
Scientists have identified possible black hole candidates that are more distant, but this is the oldest one that has been confirmed with spectroscopy, he added.
The galaxy that harbors the newfound black hole was also a fascinating discovery, the researchers said. It’s part of a class of galaxies nicknamed “Little Red Dots” because they emit red wavelengths of light and are very compact and unexpectedly bright, according to Taylor.
Not much is known yet about Little Red Dots, but they were first spotted by the James Webb Space Telescope. Though some have been spotted relatively nearby, Finkelstein said they were likely more common in the early universe.
Studying the CAPERS-LRD-z9 galaxy may yield clues about how Little Red Dots came to be and what causes their distinct red color, the researchers said. It may also provide clues about how such an old black hole came to be so large early on in the universe’s evolution.
In follow-up studies, the researchers are hoping to find other black holes in the distant universe that are just as old — if not older.
“We only ever survey very tiny areas of the sky with the James Webb Space Telescope,” Finkelstein said. “So, if we find one thing, there’s got to be a lot more out there.”
