Webb Space Telescope detects oldest 'dead' galaxy

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Astronomers have discovered the oldest “dead” galaxy ever observed while studying the universe with the James Webb Space Telescope, one of the deepest views of the distant universe made with the observatory to date.

The galaxy existed when the universe was only about 700 million years old from its current age of about 13.8 billion years. But something caused the galaxy to suddenly stop forming stars as quickly as it began more than 13 billion years ago, and researchers have yet to uncover the reason.

A report describing the discovery appeared Wednesday in the magazine nature. Studying the galaxy could reveal new insights into the early universe and the factors that influence star formation within galaxies, according to the authors.

“The first few hundred million years of the universe was a very active phase, in which a lot of gas clouds collapsed to form new stars,” said lead study author Tobias Loeser, a doctoral student in extragalactic astrophysics at the Kavli Institute of Cosmology at the University of Cambridge. In the current situation. “Galaxies need a rich supply of gas to form new stars, and the early universe was an all-you-can-eat buffet.”

The research team was surprised to find a so-called dead galaxy that lived quickly and died young shortly after the Big Bang that created the universe.

“(Normally) only later in the universe do we start to see galaxies stop forming stars, whether it's because of a black hole or something else,” said study co-author Dr. Francesco DiEugenio, an astrophysicist and postdoctoral researcher at Kavli. “. Institute of Cosmology in a statement.

Star formation stops when environmental factors deprive a galaxy of the gas needed to birth new stars.

Supermassive black holes or violent interactions between stars could be the cause of gas being expelled from galaxies, leading to a rapid halt in star formation. Or the process of stellar birth could consume so much gas that there is not enough time to replenish it to ensure the process continues into the future.

“We are not sure whether any of these scenarios can explain what we have now seen with Webb,” said study co-author Roberto Maiolino, professor of experimental astrophysics at Cavendish Laboratory and the Kavli Institute of Cosmology at the University of Cambridge. a permit.

“Until now, to understand the early universe, we have used models based on the modern universe,” Maiolino added. “But now that we can see further back in time, and notice that star formation has died down very quickly in this galaxy, we may need to reconsider Models based on the modern universe.

Webb's observations revealed that the newly discovered galaxy, named JADES-GS-z7-01-QU, experienced a brief, active burst of star formation that lasted between 30 million and 90 million years before star birth suddenly stopped.

“Everything seems to happen faster and more dramatically in the early universe, and this may include galaxies transitioning from star formation to dormancy,” Loeser said.

The dead galaxy revealed by the study is not the first that astronomers have encountered, but it is the oldest that has been observed so far.

Furthermore, the galaxy also had a low-mass, similar to a dwarf galaxy near the Milky Way known as the Small Magellanic Cloud – which is still forming new stars. Previously observed dead galaxies were much larger, adding another advantage to Webb's discovery.

The newly discovered galaxy is located billions of light-years from Earth, and a light-year is the distance a ray of light travels in a year, or more than 5.88 trillion miles (9.46 trillion km). So Webb is essentially observing the galaxy as it was in the past, and astronomers have not ruled out the possibility that it may have resurrected and started forming stars again.

“We are looking for other galaxies like this one in the early universe, which will help us put some constraints on how and why galaxies stop forming new stars,” DiEugenio said. “It may be the case that galaxies in the early universe ‘die’ and come back to life, and we will need more observations to help us figure that out.”