Astronomers are discovering which could be the most distant galaxy so far

Recently, astronomers have skipped each other in the past. Last week, a group using the Hubble Space Telescope announced it had discovered the most distant and earliest star ever seen, nicknamed Earendel, which shone 12.9 billion years ago, just 900 million years after the Big Bang. .

Now another international group of astronomers extending the boundaries of the world’s largest telescopes say they have discovered what appears to be the earliest and most distant collection of starlight ever seen: a reddish spot with the useful name HD1 which spills huge amounts of energy just 330 million years after the Big Bang. This realm of time has so far been unexplored. Another spot, HD2, looks almost as far away.

Astronomers can only guess what these spots are – galaxies or quasars or maybe something else – while waiting to be able 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 space as it evolves from virgin primordial fire into planets, life and us.

“I get excited as a child who notices the first fireworks in a great and long-awaited show,” said Fabio Pacucci of the Harvard-Smithsonian Center for Astrophysics. “This may be one of the first flashes of light to illuminate space in a show that eventually created every star, planet and even flower we see around us today – more than 13 billion years later.

Dr. Pakuchi 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. Their findings were published Thursday in The Astrophysical Journal and the Monthly Bulletin of the Royal Astronomical Society. Their work was also reported in Sky & Telescope magazine earlier this year.

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

“The red color of HD1 matched the expected characteristics of a galaxy 13.5 billion light-years away from us surprisingly well, which made me shudder when I discovered it,” Dr Hurricane said in a statement from the Center for Astrophysics.

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

This dates the estimated galaxy to just 330 million years after the start of time, falling into the hunting ground of the Webb telescope, which will also be able to confirm the redshift measurement.

“If the redshift from ALMA can be confirmed, then it would be a spectacular object,” said Marcia Rique of the University of Arizona, who is the 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 hydrogen and helium created during the primary explosion began to condense into the first stars known as Population 3 stars. 1 and 2, which have large amounts of heavier elements, are present in galaxies today). Such stars, composed only of hydrogen and helium, have never been observed and would be much larger and brighter than those in the universe today. They would burn hot and die quickly in supernova explosions, which then started chemical evolution, polluting the pristine universe with elements like oxygen and iron that are part of us.

Dr Pacucci said they first thought that HD1 and HD2 were what are called star burst galaxies, which are carried by new stars. But after further research, they found that HD1 appears to produce stars more than 10 times faster than such galaxies usually do.

Another possibility, Dr. Pacucci said, is that this galaxy gave birth to the first ultra-luminous stars of Population 3. Another explanation is that all this radiation comes from material spraying into a supermassive black hole 100 million times larger. from the mass of the sun. But astronomers have trouble explaining how a black hole could have grown so large so early in space.

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

“HD1 would be 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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