The entire universe knows when a supermassive black hole is eating: these monstrously massive objects at the heart of galaxies feast on falling matter, and this process generates radiation so bright it can dwarf the billions of stars in its host galaxy. These active galactic nuclei are called quasars.
Sometimes when galaxies merge, you can spot multiple quasars in what becomes one larger galaxy. Such galactic mergers are thought to be integral to the evolution of galaxies, and scientists have observed galaxies with more than one quasar in the entire universe – but very few examples in the very distant universe.
In a new study published Wednesday in the journal Nature, researchers describe the discovery of a galaxy with two active quasars about 29 billion light-years away. A galaxy formed by the merger of two galaxies when the universe was only three million years old, the first time such a pair of quasars was discovered at that time.
“We don’t see many double quasars at this early time. And that’s why this discovery is so exciting,” said the study’s lead author, Yu-Ching Chen, a graduate student in astronomy at the University of Illinois at Urbana-Champaign, in a statement. It’s a finding that he says will “eventually tell us about the emergence of supermassive black holes in the early Universe and the frequency of these mergers.”
And understanding galaxy mergers and supermassive black holes can help scientists understand star formation in galaxies, and ultimately the processes that lead to the evolution of Earth-like planets where life forms can gaze. distant black holes.
Lunch at Cosmic Noon
Using an array of instruments, researchers have discovered two supermassive black holes potentially orbiting each other as a binary pair about 10,000 light-years apart in a single galaxy, a telltale sign that this galaxy was the result of the merger of two small galaxies. This galaxy existed during what astronomers call “cosmic noon,” the period around 10 to 11 billion years ago when star formation across the cosmos was at its peak.
It was not an easy discovery. Even finding two quasars in a galaxy near Earth is difficult, because most of these pairs are so close that they cannot be distinguished unless they are actively feeding, i.e. they accredit a swelling material. According to a press release from the Gemini North Observatory in Hawaii, which participated in the study, typically only one in 100 supermassive black holes accumulates at any given time.
The discovery of this unlikely feeding pair of remarkably distant supermassive black holes began with the Hubble Space Telescope, which returned the first signs of distant quasars.
The researchers then turned to archived observations from the European Space Agency’s Gaia Space Telescope, which regularly scans large swaths of the sky to map more than two billion celestial objects and monitor their evolution. Gaia’s observations of the quasars found by Hubble showed a “jolt” that suggested changes in both quasars.
The research team then used instruments from the Gemini North Observatory, NASA’s Chandra X-ray Observatory and other instruments to confirm the results.
“The confirmation process was not easy and we needed a network of telescopes covering the radio X-ray spectrum to finally confirm that this system is indeed a pair of quasars,” said Yue Shen, astronomer from the University of Illinois and co-author of the study. said in a statement.
The researchers believe that the merging of distant and ancient galaxies shows a galaxy on the way to becoming an elliptical galaxy, believed to be the end point of galactic evolution. Elliptical galaxies tend to contain older stars and show few new star formations.
How such a galactic merger at the peak of star formation at cosmic noon leads to an aged galaxy devoid of long stars is the focus of ongoing research. Some research suggests that supermassive black holes could limit star formation in galaxies.