The first massive galaxies suddenly stopped producing stars

They burned the candles of their lives at both ends and then “died” young. These are six ancient and massive galaxies that astronomers describe today. They first formed many stars in a short time. Then they ran out of fuel. And was forced to run on empty.

Even today ours Universe manufactures stars daily. But when he was only three billion years old – equivalent to 20% of his current age – he experienced the most productive period in its entire history. But to turn The Hubble Space Telescope (Nasa) and Alma, Atacama Large Millimeter / Submillimeter Antenna Array, for objects dating back to the time researchers have just made an amazing discovery. Six galaxies massive that apparently lacked the hydrogen needed to make stars.

“We thought that at that time all the galaxies formed a lot of stars. And that the most massive ancient galaxies in the universe had been induced to slow down the speed at which they formed stars just a few billion years later. big bang. But our work shows that these galaxies have not really slowed down in reality. They literally ran on empty.says Kate Whitaker, an astronomer at the University of Massachusetts (USA), in a press release.

It was a combination of observational techniques that enabled the researchers to make the discovery. With the Hubble Space Telescope, they were able to locate the stars in galaxies and thus places star formation old. Together with Alma, they were able to detect traces of cold hydrogen, indicating where stars may still form in the future. Finally, thanks to a gravitational lens effect produced by a cluster of galaxies massive in the foreground and offers one light amplified in all wavelengths and one solution space, they were able to study the details of these six mysterious galaxies.

Galaxies starving for hydrogen

“Galaxies that do not make many stars are dying out pretty quickly, and they are becoming difficult for us to observe. The gravitational lensing effect allows us to study them anyway. “, says Justin Spilker, a researcher at the University of Texas (USA). And to understand that these six galaxies did not stop forming stars after a sudden inefficiency in the conversion of hydrogen. But rather due to an depletion of the reservoirs of gas cold.

How ? That astronomers still ignore it. Maybe because ofenergy injected by black holes supermassive and which heated all the gas in these galaxies. Maybe also because the supply of cold gas to these galaxies was suddenly interrupted. But whatever the case, these six galaxies seem quite unable to fill their fuel tanks and therefore unable to restart the star-making engine.

Still a lot to learn …

“We still have a lot to learn about why the most massive galaxies were formed so early in the universe and why they stopped star formation when they supposedly had so much cold gas.explains Kate Whitaker. The simple fact that these huge animals in the cosmos formed 100 billion stars in just one billion years and then suddenly stopped their star formation is a mystery we all want to solve, and here we have the first clue. “

Futura in the starsit is the inevitable event for astronomy and space enthusiasts. Every 1st of the month you can find us for a complete tour of the month’s ephemeris with advice to best observe what’s going on in the sky. A special episode released every 15th of the month will offer you to learn more about a particular object or event that will mark astronomical news and space news.

Interested in what you just read?

Leave a Comment