Most Distant Astronomical Object Ever Spotted. It's 13.5 Billion Light-Years Away

The researchers proposed two ideas. One idea is that HD1 may be forming stars at an astounding rate and is possibly even home to Population III stars, which are the universe's very first stars.

New Delhi: A team of astronomers led by researchers at the Center for Astrophysics | Harvard and Smithsonian, has detected the most distant astronomical object ever. 

The object, named HD1, is a galaxy candidate 13.5 billion light-years away.

The galaxy candidate was described Thursday in the Astrophysical Journal (ApJ).

HD1 Harbours Universe’s First Stars Or A Supermassive Black Hole?

The researchers proposed two ideas. One idea is that HD1 may be forming stars at an astounding rate and is possibly even home to Population III stars, which are the universe's very first stars. Population III stars have never been observed until now. The other idea is that HD1 may contain a supermassive black hole about 100 million times the mass of the Sun. 

Researchers have begun to speculate exactly what the galaxy is, in an accompanying paper published in the Monthly Notices of the Royal Astronomical Society Letters (MNRAS).

Fabio Pacucci, the lead author of the MNRAS study, and co-author of the discovery paper published in ApJ, said that answering questions about the nature of a source so far away can be challenging, according to a statement issued by the Center for Astrophysics. He explained that it is like guessing the nationality of a ship from the flag it flies, while being faraway ashore, with the vessel in the middle of a gale and dense fog. 

HD1 Is Extremely Luminous

The newly discovered astronomical object is extremely bright in ultraviolet light. Pacucci said this is because "some energetic processes are occuring there, or better yet, did occur some billions of years ago."

The researchers, at first, assumed that HD1 was a standard starburst galaxy, which is a galaxy that is creating stars at a high rate. The scientists calculated how many stars HD1 was producing, and obtained "incredible rate". 

HD1 Forms More Than 100 Stars Every Year

They found that HD1 forms more than 100 stars every single year, which is at least 10 times higher than what is expected for starburst galaxies.

This is what made the researchers suspect that HD1 might not be forming normal, everyday stars.

Pacucci said the very first population of stars that formed in the universe were more massive, more luminous, and hotter than modern stars.

The scientist said that if the stars produced in HD1 are assumed to be Population III stars, then the properties of the galaxy candidate can be explained more easily. 

He said that Population III stars are capable of producing more UV light than normal stars, which could clarify the extreme ultraviolet luminosity of HD1. 

How A Supermassive Black Hole Could Be Responsible For HD1’s Extreme Luminosity

A supermassive black hole could also be responsible for the extreme luminosity of HD1, the study said. This is because a supermassive black hole would gobble down enormous amounts of gas, and high energy photos may be emitted by the region around the black hole.

According to the authors, the black hole in HD1 could be by far the earliest supermassive black hole known to humankind. 

Avi Loeb, an astronomer at the Center for Astrophysics and co-author on the MNRAS study, said that HD1 would represent a giant baby in the delivery room of the early universe. 

The discovery was made as a result of more than 1,200 hours of observing time with the Subaru Telescope, VISTA Telescope, UK Infrared Telescope, and Spitzer Space Telescope.

Yuichi Harikane, an astronomer at the University of Tokyo who discovered the galaxy candidate, said it was very hard to find HD1 out of more than 700,000 objects. He further said that HD1's red colour matched the expected characteristics of a galaxy 13.5 billion light-years away surprisingly well, giving him "a little bit of goosebumps" when he found it.

How Far Is HD1 From The Current Record Holder For Farthest Galaxy?

The current record-holder for the farthest galaxy is GN-z11. According to the study, HD1 is 100 million light years away than GN-z11. The researchers confirmed the distance using the Atacama Large Millimeter/submillimeter Array (ALMA).

The astronomers intend to observe HD1 again using the James Webb Space Telescope, to verify its distance from Earth.

HD1 will be the most distant and oldest galaxy ever recorded, if the current calculations prove correct, the authors noted in the study. 

Loeb said that a black hole in HD1 must have grown out of a massive seed at an unprecedented rate. "Once again, nature appears to be more imaginative than we are," he said.