Galaxy 13.5 billion light-years from Earth most distant object ever spotted

By Stephen Beech via SWNS

A galaxy has become the most distant astronomical object ever spotted.

Named HD1, it is some 13.5 billion light-years from Earth.

The international team who made the discovery have begun to speculate exactly what the galaxy is.

They have proposed two ideas: HD1 may be forming stars at an astounding rate and is possibly even home to Population III stars, the universe’s very first stars - which, until now, have never been observed.

Alternatively, HD1 may contain a supermassive black hole about 100 million times the mass of our Sun.

Doctor Fabio Pacucci, an astronomer at the Centre for Astrophysics in the United States, said: “Answering questions about the nature of a source so far away can be challenging.

“It’s 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.

"One can maybe see some colours and shapes of the flag, but not in their entirety. It’s ultimately a long game of analysis and exclusion of implausible scenarios.”

He said HD1 is extremely bright in ultraviolet light, adding: "Some energetic processes are occurring there or, better yet, did occur some billions of years ago."

At first, the researchers assumed HD1 was a standard starburst galaxy, one that is creating stars at a high rate.

But after calculating how many stars HD1 was producing, they found “an incredible rate."

Dr. Pacucci said: "HD1 would be forming more than 100 stars every single year. This is at least 10 times higher than what we expect for these galaxies.”

That’s when the team began suspecting that HD1 might not be forming normal, everyday stars.

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

“If we assume the stars produced in HD1 are these first, or Population III, stars, then its properties could be explained more easily.

"In fact, Population III stars are capable of producing more UV light than normal stars, which could clarify the extreme ultraviolet luminosity of HD1.”

However, a supermassive black hole could also explain the "extreme luminosity" of HD1. As it gobbles down enormous amounts of gas, high energy photons may be emitted by the region around the black hole, according to the research team.

If that’s the case, they explained that it would be by far the earliest supermassive black hole known to humankind, observed much closer in time to the Big Bang compared to the current record-holder.

HD1 would represent a giant baby in the delivery room of the early universe.

Professor Avi Loeb, also an astronomer at the Centre for Astrophysics, said: “It breaks the highest quasar redshift on record by almost a factor of two, a remarkable feat.”

HD1 was discovered after more than 1,200 hours of observing time with the Subaru Telescope, VISTA Telescope, UK Infrared Telescope and Spitzer Space Telescope.

Doctor Yuichi Harikane, an astronomer at the University of Tokyo in Japan who discovered the galaxy, said: “It was very hard work to find HD1 out of more than 700,000 objects.

“HD1's red color matched the expected characteristics of a galaxy 13.5 billion light-years away surprisingly well, giving me a little bit of goosebumps when I found it.”

The team then conducted follow-up observations to confirm the distance, which is 100 million light-years further than GN-z11, the current record-holder for the furthest galaxy.

The research team are due to again observe HD1 to verify its distance from Earth. If current calculations prove correct, HD1 will be the most distant - and oldest - galaxy ever recorded.

The same observations will allow the team to dig deeper into HD1’s identity and confirm if one of their theories is correct.

Prof Loeb added: “Forming a few hundred million years after the Big Bang, 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.”

The findings were published in Monthly Notices of the Royal Astronomical Society Letters.