Astronomers Find What Might Be the Most Distant Galaxy Yet

Astronomers have been skipping each other in the past lately. Last week, a group using the Hubble Space Telescope announced they had discovered what may be the earliest and most distant star ever seen, dubbed Earendel, which twinkled 12.9 billion years ago, just 900 million years after the Big Bang. .

Now another international group of astronomers, pushing the limits of Earth’s largest telescopes, say they’ve discovered what appears to be the oldest and most distant collection of starlight ever seen: a reddish blob helpfully named HD1, which was spilling out prodigious amounts of starlight. energy only 330 million years after the Big Bang. That realm of time is as yet unexplored. Another drop, HD2, appears almost as far away.

Astronomers can only guess what these spots are — galaxies or quasars or maybe something else entirely — as they wait for a chance to observe them with the new James Webb Space Telescope. But whatever they are, astronomers say, they could shed light on a crucial phase in the cosmos as it evolved from pristine primordial fire to planets, life and us.

“I am excited like a child seeing the first fireworks in a magnificent and long-awaited spectacle,” said Fabio Pacucci of the Harvard-Smithsonian Center for Astrophysics. “This could well be one of the first flashes of light to illuminate the cosmos in a spectacle that ultimately created every star, planet, and even flower 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 that 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 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 an object is from us, the faster it is moving away from us. Just as the sound of a receding ambulance siren shifts to a lower pitch, that movement causes light from an object to shift to longer, redder wavelengths. Searching for the most distant galaxies, astronomers examined some 70,000 objects, and HD1 was the reddest they could find.

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

However, the gold standard for cosmic distances is redshift, which is obtained by obtaining a spectrum of the object and measuring how much the wavelengths emitted by characteristic elements have increased or redshifted. Using the Atacama Large Millimeter/submillimeter Array, or ALMA, a collection of radio telescopes in Chile, Dr. Harikane and his team obtained a tentative redshift for HD1 of 13, which means that the wavelength of the light emitted by an oxygen atom had been stretched to 14 times its wavelength at rest. The redshift of the other spot has not been determined.

That dated the putative galaxy to just 330 million years after the beginning of time, right in the hunting ground of the Webb telescope, which will also be able to confirm the redshift measurement.

“If ALMA’s redshift can be confirmed, then this would be a really spectacular object,” said Marcia Rieke of the University of Arizona, who is Principal Investigator of the Webb telescope.

According to the story told by astronomers, the path to the universe as we know it began about 100 million years after the Big Bang, when the hydrogen and helium created in the primordial explosion began to condense into the first stars, known as stars. of Population 3 (Populations 3 stars). 1 and 2, which have large amounts of heavier elements, are present in today’s galaxies). These types of stars, composed only of hydrogen and helium, have never been observed, and would have been much larger and brighter than those that currently exist in the universe. They would have quickly burned up and died in supernova explosions that then started chemical evolution contaminating a pristine universe with elements like oxygen and iron, the stuff of us.

Dr. Pacucci said that they first thought that HD1 and HD2 were what are called starburst galaxies, filling up with new stars. But after further investigation, they found that HD1 seemed to be churning out stars more than 10 times faster than such galaxies typically do.

Another possibility, Dr. Pacucci said, is that this galaxy was giving birth to those first ultraluminous Population 3 stars. Yet another explanation is that all this glow is coming from material splashing into a supermassive black hole 100 million times the mass of the sun. But astronomers are having trouble explaining how a black hole could have grown so large so early in cosmic time.

Was he born like this, in the chaos of the Big Bang, or was he just terribly hungry?

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

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