Using the most powerful telescope ever built, astronomers have identified a very large, densely packed galaxy 25 billion light-years away. The galaxy, known as GS-9209, formed just 600 to 800 million years after the Big Bang and is the oldest of its kind ever found, the researchers say. A team led by Edinburgh researchers used the James Webb Space Telescope to reveal GS-9209’s features in detail for the first time.

A galaxy full of stars

Although GS-9209 is about 10 times smaller than the Milky Way, it has the same number of stars as our galaxy. The team says their total mass is about 40 billion times that of our Sun and formed just before GS-9209 stopped forming stars.

GS-9209 is the earliest known example of a no longer star-forming galaxy, known as a dormant galaxy. When the team observed it 1.25 billion years after the Big Bang, no stars had formed in the galaxy for about half a billion years.

Disconnection theory

The analysis also shows that GS-9209 contains a supermassive black hole at its center, five times larger than astronomers would expect in a galaxy with so many stars. The team says this discovery could explain why GS-9209 stopped forming new stars.

The accumulation of supermassive black holes releases large amounts of high-energy radiation that can heat and expel gas from galaxies. This may have caused star formation to cease on GS-9209, as stars form when dust clouds and gas particles inside galaxies collapse under their own weight.

exploration of the galaxy

The GS-9209 was first awarded an Edinburgh Ph.D. in 2004. student Karina Caputi, who at the time was led by professors Jim Dunlop and Ross McClure in the university’s School of Physics and Astronomy. Caputi is currently a professor at the University of Groningen, Netherlands.

“The James Webb Space Telescope has already shown that galaxies are growing earlier than we anticipated during the first billion years of cosmic history. This study details the history of GS-9209, which managed to form as many stars as our Milky Way just 800 million years after the Big Bang. “It offers our first really detailed look at the properties of these early galaxies. It was a big surprise that we also saw a very massive black hole in this galaxy, and it puts a lot of weight on the idea that it was these black holes that prevented star formation in early galaxies,” says Physics and Astronomy at the University of Edinburgh.