A monster at the dawn of time

An international team of astronomers, led by The University of Texas at Austin’s Cosmic Frontier Center, has identified the most distant black hole ever confirmed. It and the galaxy it calls home, CAPERS-LRD-z9, are present 500 million years after the Big Bang. That places it 13.3 billion years into the past, when our universe was just 3% of its current age. As such, it provides a unique opportunity to study the structure and evolution of this enigmatic period.

“When looking for black holes, this is about as far back as you can practically go. We’re really pushing the boundaries of what current technology can detect,” said Anthony Taylor, a postdoctoral researcher at the Cosmic Frontier Center and lead on the team that made the discovery.

The research is published in The Astrophysical Journal.

“While astronomers have found a few, more distant candidates,” added Steven Finkelstein, a co-author on the paper and director of the Cosmic Frontier Center, “they have yet to find the distinct spectroscopic signature associated with a black hole.”

With spectroscopy, astronomers split light into its many wavelengths to study an object’s characteristics. To identify black holes, they search for evidence of fast-moving gas. As it circles and falls into a black hole, the light from gas moving away from us is stretched into much redder wavelengths, and light from gas moving toward us is compressed into much bluer wavelengths.

“There aren’t many other things that create this signature,” explained Taylor. “And this galaxy has it.”

The team used data from the James Webb Space Telescope’s CAPERS (CANDELS-Area Prism Epoch of Reionization Survey) program for its search. Launched in 2021, JWST provides the most far-reaching views into space available, and CAPERS provides observations of the outermost edge.

“The first goal of CAPERS is to confirm and study the most distant galaxies,” said Mark Dickinson, a co-author on the paper and the CAPERS team lead. “JWST spectroscopy is the key to confirming their distances and understanding their physical properties.”

Initially seen as an interesting speck in the program’s imagery, CAPERS-LRD-z9 turned out to be part of a new class of galaxies known as “Little Red Dots.” Present only in the first 1.5 billion years of the universe, these galaxies are very compact, red, and unexpectedly bright.

“The discovery of Little Red Dots was a major surprise from early JWST data, as they looked nothing like galaxies seen with the Hubble Space Telescope,” explained Finkelstein. “Now, we’re in the process of figuring out what they’re like and how they came to be.”

CAPERS-LRD-z9 may help astronomers do just that.

For one, this galaxy adds to mounting evidence that supermassive black holes are the source of the unexpected brightness in Little Red Dots. Usually, that brightness would indicate an abundance of stars in a galaxy. However, Little Red Dots exist at a time when such a large mass of stars is unlikely.

On the other hand, black holes also shine brightly. That’s because they compress and heat the materials they’re consuming, creating tremendous light and energy. By confirming the existence of one in CAPERS-LRD-z9, astronomers have found a striking example of this connection in Little Red Dots.

The newfound galaxy may also help answer what causes the distinct red color in Little Red Dots. That may be thanks to a thick cloud of gas surrounding the black hole, skewing its light into redder wavelengths as it passes through.

“We’ve seen these clouds in other galaxies,” explained Taylor. “When we compared this object to those other sources, it was a dead ringer.”

This galaxy is also notable for how colossal its black hole is. Estimated as up to 300 million times that of our sun, its mass measures up to half that of all the stars in its galaxy. Even among supermassive black holes, this is particularly big.

Finding such a massive black hole so early on provides astronomers a valuable opportunity to study how these objects developed. A black hole present in the later universe will have had diverse opportunities to bulk up during its lifetime. But one present in the first few hundred million years wouldn’t.

“This adds to growing evidence that early black holes grew much faster than we thought possible,” said Finkelstein. “Or they started out far more massive than our models predict.”

To continue their research on CAPERS-LRD-z9, the team hopes to gather more, higher-resolution observations using JWST. This could provide greater insight into it and the role black holes played in the development of Little Red Dots.

“This is a good test object for us,” said Taylor. “We haven’t been able to study early black hole evolution until recently, and we are excited to see what we can learn from this unique object.”