Astronomers are finding what could be the farthest galaxy to date

Lately, astronomers have taken a leap between them in the past. Last week, a group using the Hubble Space Telescope announced that they had discovered what could be the farthest and oldest star ever seen, named Earendel, which sparkled 12.9 billion years ago, only 900 million years after the Big Bang.

Now, another international group of astronomers, pushing the boundaries of the largest telescopes on Earth, say they have discovered what appears to be the oldest and most distant starlight collection ever seen: a reddish spot called usefully HD1, which was pouring prodigious amounts of energy only 330 million years after the Big Bang. This realm of time is hitherto unexplored. Another spot, HD2, appears almost as far away.

Astronomers can only guess what these spots are: galaxies or quasars, or perhaps something else entirely, while waiting for the opportunity to observe them with the new James Webb space telescope. But whoever they are, astronomers say, could shed light on a crucial phase of the cosmos as it evolved from the pristine primordial fire to the planets, life, and us.

“I was thrilled when I was a kid watching the first fireworks in a magnificent, long-awaited show,” said Fabio Pacucci of the Harvard-Smithsonian Center for Astrophysics. “This could be one of the first lights to illuminate the cosmos in a show that finally created all the stars, planets and even flowers we see around us today, more than 13 billion years later.”

Dr. Pacucci was part of a team led by Yuichi Harikane of the University of Tokyo who spent 1,200 hours using various ground-based telescopes to search for very early galaxies. His findings were published Thursday in The Astrophysical Journal and in the Monthly Notices of the Royal Astronomical Society. His work was also reported in Sky & Telescope magazine earlier this year.

In the expanding universe, the farther away an object is from us, the faster it moves away from us. Just as the sound of a receding ambulance siren changes to a lower pitch, this movement causes an object’s light to change to longer, red wavelengths. In search of the most distant galaxies, astronomers screened about 70,000 objects, and HD1 was the reddest they could find.

“The red color of the HD1 matched surprisingly well with the expected features of a galaxy 13.5 billion light-years away, which gave me some goosebumps when I found it,” he said. Dr. Harikane in a statement issued by the Center for Astrophysics.

The gold standard for cosmic distances, however, is the redshift, derived from obtaining a spectrum of the object and measuring how much the wavelengths emitted by the reds have increased or shifted to red. characteristic elements. Using the Atacama Large Millimeter / Submillimeter Array, or ALMA, a collection of radio telescopes in Chile, Dr. Harikane and his team obtained a provisional redshift for HD1 of 13, meaning that the wavelength of the light emitted by an oxygen atom had been stretched to 14 times its wavelength. ‘wave at rest. The redshift of the other spot has not been determined.

This dated the presumed galaxy only 330 million years after the start of time, right on the Webb telescope’s hunting ground, which will also be able to confirm the redshift.

“If ALMA’s redshift can be confirmed, it would be a spectacular object,” said Marcia Rieke of the University of Arizona, who is a senior researcher on the Webb telescope.

According to the story of astronomers, the path to the universe as we know it began about 100 million years after the Big Bang, when hydrogen and helium created in the primordial explosion began to condense. -se in the first stars, known as stars of population 3 (Populations). 1 and 2, which have large amounts of heavier elements are present in current galaxies). These stars, composed only of hydrogen and helium, have never been observed, and would have been much larger and brighter than those in the current universe. They would have burned hot and died quickly in supernova explosions that then propelled the chemical evolution by polluting a pristine universe with elements like oxygen and iron, the thing of us.

Dr. Pacucci said they first thought that HD1 and HD2 were what are called star burst galaxies, which are filled with new stars. But after further research, they found that HD1 appeared to be producing stars more than 10 times faster than these galaxies usually do.

Another possibility, Dr. Pacucci said, is that this galaxy was giving birth to the first ultra-bright stars in population 3. Another explanation is that all this glow comes from material splattered in a supermassive black hole 100 million times the mass. of the sun. But astronomers have trouble explaining how a black hole could have grown so early in cosmic time.

Was he born that way, in the chaos of the Big Bang, or was he just super hungry?

“HD1 would represent a giant baby in the delivery room of the early universe,” said Avi Loeb, co-author of Dr. Pacucci’s article.

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