James Webb’s telescope was the first to notice a distant galaxy

The James Webb Space Telescope was the first known galaxy to be spotted suddenly forming stars.

The galaxy, named GS-9209, had its star formation extinguished more than 12.5 billion years ago, researchers report on January 26 at arXiv.org. This was only a little more than a thousand years after the Big Bang. Its existence reveals new details about how galaxies live and die throughout cosmic time.

“It’s a significant finding,” says University of Massachusetts Amherst astronomer Mauro Giavalisco, who was not involved in the new study. “We really want to know when the conditions are ripe for the extinction phenomenon to spread across the universe.” This study shows that there were at least some extinct galaxies in the young universe.

GS-9209 was first noticed in the early 2000s. In recent years, telescope-based observations have identified it as a possible extinct galaxy, based on the wavelengths of the light it emits. But the Earth’s atmosphere absorbs the infrared focus that could confirm the distance of the galaxy and that its star days were behind it, so it could not know for sure.

So astrophysicist Adam Carnall and colleagues turned to the James Webb Space Telescope, or JWST. The observatory is very sensitive to infrared light, and is above the shielding of the Earth’s atmosphere.SN: 1/24/22). “That’s why JWST exists,” said Carnallus, of the University of Edinburgh. JWST also has a much greater sensitivity than previous telescopes to see fainter, more distant galaxies. While the largest telescopes on Earth may be able to see GS-9209 in detail after a month of observing, “JWST will pick this up in a few hours.”

Using JWST observations, Carnall and colleagues found that GS-9209 formed most of its stars within a 200-million-year period, starting about 600 million years after the Big Bang. In that brief cosmic moment, it has built up about 40 billion solar masses worth of stars, around which the Milky Way has.

This rapid construction suggests GS-9209 formed from a giant cloud of vapor and dust that collapsed and ignited the star at the same time, Carnall says. “It’s pretty clear now that most of the stars formed in this big explosion.”

Astronomers used to think that this method of galaxy formation, called monolithic collapse, was the way most galaxies formed. But the idea fell out of favor, replaced by the idea that large galaxies form from the slow collapse of many smaller ones.SN: 5/17/21).

“It now looks, at least for this matter, a monolithic collapse,” said Carnallus. “This is the most reliable evidence yet that this type of galaxy evolution is happening.”

But what caused the galaxy’s star-forming fury to suddenly stop seems to be the culprit, feeding an active black hole. JWST observations detected extra-infrared light emission associated with a rapidly accreting mass of hydrogen, which is a sign of an accreting black hole. A black hole appears to be up to a million times the mass of the sun.

To reach this mass less than a billion years after the birth of the universe, the black hole must have fed faster in its lifetime, says Carnallus (SN: 3/16/18). In order to sink in, a glowing globe of burning gas and dust gathered around him.

“If you have all the radiation spewing out of a black hole, any gas that’s nearby has to be incredibly heated, which prevents it from falling into the stars,” says Carnall.

More observations with future telescopes, such as the largest telescope planned in Chile, could help to figure out more precisely how the galaxy was formed.