Discovered what could be the oldest and most distant astronomical object in the universe

If on March 30, NASA announced the discovery of the Hubble Space Telescope, named Earendel in honor of JRR Tolkien’s telescope, located 12.9 billion light-years from Earth, now another astronomical object is even further away. , 13.5 billion light years. With a less poetic name – they called it HD1 – a galaxy or supermassive black hole would form. Simply 300 million years after the Big Bang.

The discovery was made by an international team of astronomers, including researchers at the Harvard-Smithsonian Center for Astrophysics. The achievement is collected in the magazine this Thursday Astrophysical Journal. In another accompanying article, published in St. Monthly letters from the Royal Astronomical SocietyScientists speculate on the nature of this astronomical object.

The group, according to a press release from the Harvard-Smithsonian Center for Astrophysics, offers two ideas: HD1 might have generated stars at astonishing speeds, and it might even have been home to the so-called III stars of the population, the first stars. In a world that has never been observed before. Another possibility is that the HD1 contained a supermassive black hole with a mass 100 million times that of our Sun.

“Answering questions about the nature of such a distant source can be challenging,” said Fabio Pacucci, co-author of the discovery article and an astronomer at the Center for Astrophysics in a press release. “It’s like guessing a ship’s nationality from the flag it flies. You can see some of the colors and shapes of the flag, but not completely. In short, this is a long game of analysis and elimination of unbelievable scenarios.

The fact is that HD1 emits extremely bright ultraviolet light, which Pakuch explains by “certain energy processes that took place several billion years ago.” Initially, researchers believed that HD1 was the standard galaxy from which new stars were emerging at high speeds; But after calculating how many stars HD1 was producing, they realized they were emerging at an incredible rate: more than 100 stars a year.

HD1 is a giant baby in an early world maternity ward

Avi Loeb
– Astronomer at the Harvard-Smithsonian Center for Astrophysics

It is about 10 times faster, at least than from a standard galaxy. It was then that the team began to suspect that HD1 might be forming stars that were not Normal and normal.

“The first population of stars in the universe was more massive, brighter and hotter than modern stars,” Pakuchi said. “If we assume that the stars formed in HD1 are early or III population stars, then their properties are easier to explain. In fact, stars in the III population can emit more ultraviolet light than ordinary stars, which can illuminate the HD1’s extreme ultraviolet brightness. ”

Supermassive black hole

However, experts point out in the press release that the supermassive black hole could also explain the HD1’s extreme brightness. By swallowing huge amounts of gas, the region surrounding the black hole can emit high-energy photons.

If so, it would be the earliest supermassive black hole known to mankind to have been observed closer to the Big Bang than to the current record holder.

“HD1 was a giant baby in the maternity ward of the early universe,” said Avi Loeb, an astronomer at the Center for Astrophysics. HD1 was discovered after more than 1,200 hours of observation with the Subaru Telescope, the VISTA Telescope, the UK Infrared Telescope and the Spitzer Space Telescope.

It was very difficult to find HD1 among more than 700,000 objects

Yuichi Harikane
– Astronomer at the University of Tokyo

“It was very difficult to find HD1 among more than 700,000 objects,” said Yuichi Harricane, an astronomer at the University of Tokyo who discovered the galaxy. “The red color of HD1 matched the expected characteristics of a galaxy 13.5 billion light-years away, which confused me as soon as it was discovered.”

The team then made observations from Chile using the Alma (Atacama Millimeter Radio Telescope Array) radio telescope to confirm a distance that is 100 million light-years farther from GN-z11, the current record for the most distant galaxy.

Mission for James Webb

With the James Webb Space Telescope, a team of researchers will soon be watching HD1 again to check its distance from Earth. If the current calculations are correct, HD1 would be the most distant and oldest galaxy ever recorded. The same observations will allow the team to delve into the identity of HD1 and confirm whether one of their theories is correct.