Astronomers Discovered A Massive Dead Galaxy Using The James Webb Space Telescope (2025)

Astronomers have discovered the most distant massive “dead” galaxy yet, using the James Webb Space Telescope (JWST). The finding suggests that galaxies were dying much earlier in the universe than previously thought.

For a galaxy, death refers to intense star formation slowing down or even coming to a halt, which prevents a galaxy from growing.

Early dead galaxies observed by the JWST were called “red and dead” galaxies due to their abundance of old small red stars and lack of massive young blue stars.

The new record-breaking galaxy, RUBIES-UDS-QG-z7, emits light that has been traveling to us for 13 billion years, which means the JWST saw it as it was 700 million years after the Big Bang. As a result, it is the first massive quiescent galaxy (MQG) seen in the beginning of the universe.

“We discovered a galaxy which formed 15 billion times the mass of the sun in stars and then stopped forming stars before the universe was only 700 million years old,” said Andrea Weibel from the University of Geneva (UNIGE) Department of Astronomy.

“This makes RUBIES-UDS-QG-z7 the most distant massive quiescent galaxy known to date.”

It was discovered as part of the “Red Unknowns: Bright Infrared Extragalactic Survey” or RUBIES program. The galaxy may challenge current models of how galaxies evolve and gradually stop growing. Scientists may have to revisit the physical processes that regulate star formation.

Immediately around the Milky Way, quiescent galaxies are commonplace. As the JWST looks further away, it has detected earlier and earlier MQGs. Several of the red and dead galaxies were found as early as 1.2 billion years after the Big Bang.

“Massive galaxies observed early in the universe only had a very limited amount of time to form their stars. This means they must have formed rapidly and efficiently, which helps us to constrain and, in some cases, even challenge theories and models of galaxy formation and growth,” said Weibel.

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“RUBIES-UDS-QG-z7, however, is not only massive but has already stopped forming stars 50 to 100 million years before we observe it, while normal galaxies at these epochs are still building up their stellar mass through star formation.”

According to Weibel, the galaxy is compact and could be an example of an object where a lot of gas and dust collected and collapsed, allowing stars to form quickly and efficiently for a long period of time. RUBIES-UDS-QG-z7 stands out because it stopped forming stars so early on.

Its light also comes entirely from stars instead of from violent conditions around a feeding black hole. It is the only object of its kind out of all the JWST data that has been investigated. Calculations show that galaxies like RUBIES-UDS-QG-z7 should account for about one in one million galaxies.

The research was published in The Astrophysical Journal.