Ancient galaxy discovered 25 billion light years away

Astronomers have used the most powerful telescope ever built to identify a massive, densely packed galaxy 25 million light years away.

Known as GS-9209, the galaxy formed around 600 to 800 million years after the Big Bang, and is the earliest of its kind found to date, researchers say.

The scientists, led by University of Edinburgh experts, used the James Webb Space Telescope (JWST) to reveal the properties of the galaxy called GS-9209 for the first time.

“The James Webb Space Telescope has already demonstrated that galaxies were growing larger and earlier than we ever suspected during the first billion years of cosmic history,” lead researcher Dr Adam Carnall, of the University of Edinburgh’s School of Physics and Astronomy, said.

“This work gives us our first really detailed look at the properties of these early galaxies, charting in detail the history of GS-9209, which managed to form as many stars as our own Milky Way in just 800 million years after the Big Bang.

“The fact that we also see a very massive black hole in this galaxy was a big surprise, and lends a lot of weight to the idea that these black holes are what shut down star formation in early galaxies.”

The researchers found that despite being around 10 times smaller than the Milky Way, GS-9209 has a similar number of stars to our own galaxy.

According to the study, their combined mass is around 40 billion times that of our sun, and they were formed rapidly before star formation in GS-9209 stopped.

GS-9209 is the earliest known example of a galaxy no longer forming stars – known as a quiescent galaxy.

When the researchers observed it at 1.25 billion years after the Big Bang, no stars had formed in the galaxy for about half a billion years.

The study also suggests there is a supermassive black hole at the centre of GS-9209.

It is five times bigger than astronomers might anticipate in a galaxy with this number of stars.

The discovery could explain why GS-9209 stopped forming new stars, the astronomers say.

When supermassive black holes grow they release huge amounts of high-energy radiation, which can heat up and push gas out of galaxies.

According to the researchers, this could have caused star formation in GS-9209 to stop, as stars form when clouds of dust and gas particles inside galaxies collapse under their own weight.

GS-9209 was first discovered in 2004 by Edinburgh PhD student Karina Caputi, who was supervised at the time by professors Jim Dunlop and Ross McLure at the university’s School of Physics and Astronomy.

The research, published in the journal Nature, was supported by the Leverhulme Trust, the Science and Technology Facilities Council and UK Research and Innovation.