Scientists have spotted the longest galaxy ever

HD1, an object in red, appears in the center of the zoom image. Credit: Harikane et al.

An international team of astronomers, including scientists at the Center for Astrophysics | Harvard & Smithsonian, has spotted the most distant astronomical phenomenon ever: a galaxy.

The galaxy candidate, called HD1, is about 13.5 billion light-years away and is described on Thursday in Astrophysical Journal. In the attached issue Monthly announcements by Royal Astronomical SocietyScientists are beginning to wonder exactly what the galaxy is.

The group proposes two ideas: HD1 could be forming stars at astonishing speeds and is possibly the home of Star Group III, the very first stars in the universe – which have never been seen before. Alternatively, HD1 may contain a giant black hole that is about 100 million times more massive than our Sun.

“It can be challenging to answer questions about the nature of the source so far away,” says Fabio Pacucci, the book’s lead author. MNRAS research, co-author of the discovery ApJ, and an astronomer at the Center for Astrophysics. “It’s like guessing the nationality of a ship from the flag it’s flying, while it’s removed ashore, with the ship in the middle of a gust of wind and dense fog. You might be able to see some of the colors and shapes of the flag, but not the whole. “It’s a long game in the end to detect and rule out improbable situations.”

HD1 is extremely bright in ultraviolet light. To explain this, “some energetic processes are taking place there or, better yet, took place a few billion years ago,” says Pacucci.

At first, the researchers assumed that HD1 was a normal star-thinning galaxy, a galaxy that produces stars at high speeds. But after calculating how many stars HD1 produced, they gained “incredible speed – HD1 would produce more than 100 stars each year. This is at least 10 times higher than we expect for these galaxies.

That was when the team began to suspect that HD1 could not be forming ordinary everyday stars.

“The first constellations of stars formed in the universe were more massive, luminous, and hotter than modern stars,” says Pacucci. “If we assume that the stars produced in HD1 are the first, or population III, stars, then it would be easier to explain their properties. In fact, the stars of Population III are capable of producing more UV light than ordinary stars, which could explain ultraviolet brightness HD1. ”

Scientists have spotted the longest galaxy ever

The timeline shows the oldest galaxy candidates and the history of the universe. Credit: Harikane et al., NASA, EST and P. Oesch / Yale.

However, the supermass black hole could also explain the bright HD1. When it absorbs an enormous amount of gas, high-energy photons can be sent from the area around the black hole.

If that is the case, it would be the oldest giant black hole known to mankind, which can be seen much closer to the Big Bang in time compared to the current record holder.

“HD1 would represent a giant baby in the universe’s delivery room,” says Avi Loeb, an astronomer at the Center for Astronomical Physics and co-author of MNRAS nám. “It breaks the highest quasar red deviation that stories go by about almost two coefficients, an incredible achievement.”

HD1 was found after more than 1,200 hours of observation time with the Subaru telescope, the VISTA telescope, the UK infrared telescope and the Spitzer space telescope.

“It was very difficult to find HD1 from more than 700,000 objects,” said Yuichi Harikane, an astronomer at the University of Tokyo who discovered the galaxy. “The red color of the HD1 matched the expected characteristics of a galaxy 13.5 billion light-years away surprisingly well and gave me a little goosebumps when I found it.”

The team then conducted follow-up observations with the Atacama Large Millimeter / Submillimeter Array (ALMA) to confirm the distance, which is 100 million light-years longer than GN-z11, the current record holder for the longest galaxy.

Using the James Webb Space Telescope, the research team will soon be monitoring HD1 again to verify its distance from Earth. If the current calculations prove correct, HD1 will be the most distant and oldest galaxy ever measured.

The same observations will allow the team to delve deeper into the HD1 ID and confirm whether one of their theories is correct.

“The black hole in HD1, which formed hundreds of millions of years after the Big Bang, must have grown out of a huge seed at an unprecedented rate,” says Loeb. “Once again, nature seems to be more imaginative than we are.

Astronomers face a giant black hole in the heart of the Milky Way, Bogmann A *

More information:
Search for H-function Lyman Break galaxies at z ~ 12-16, arXiv: 2112.09141 [astro-ph.GA], Approved for publication in MNRAS letter.

Are the newly discovered z∼13 dropout sources galaxies or quasars ?, arXiv: 2201.00823 [astro-ph.GA], Approved for publication in ApJ.

Provided by the Harvard-Smithsonian Center for Astrophysics

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