An artist 's impression of ID2299, a vestige of two galaxies that collided in the ancient universe. ESO / M. Kornmesser
The world's largest radio telescope captured a violent moment in the early universe about 9 billion years ago, shortly after the collision of two gigantic galspiral axies. Astrophysicists believe this snapshot could provide key information about the growth and evolution of galaxies - and potentially what causes them to stop growing.
The research, published in the journal Nature Astronomy on Monday, describes observations of starburst galaxy ID2299, made by the Atacama large millimeter / submillimeter array, or ALMA . After examining more than 100 galaxies, the ALMA team found ID2299 and discovered that it was undergoing a "truly extreme event," according to Emanuele Daddi, co-author and astrophysicist at the police station. French alternative energies and atomic energy (CEA) Saclay.
Editors 'top picks Subscribe now for reviews, updatesthe most interesting things and videos of the day.
Like a star-shaped galaxy, ID2299 undergoes a period of rapid star formation, where hot gases and dust accumulate and produce new stars about five times faster than average. Over time, galaxies use their dust and stars to form gas, this process slows down dramatically and structures settle into a mature growth phase that is much less busy.
ID229 9 is a bit unusual. We see it at a time when the universe was only about 4.5 billion years old. That's a lot of stars, but the researchers note that it also appears to be spewing a ton of gas into a vacuum, into a huge stream.
However, they use a much friendlier term than "vomiting". They call it a “titanic ejection”.
The team theorizes that this huge ejection, which is equivalent to environ half of the galaxy's total gas mass, was probably caused by two spiral galaxies spinning into each other, causing gravity to become all weird. Interactions between the two molten galaxies helped expel the gas quickly. However, it's the implications of their discovery for the growth and evolution of galaxies that really excite them.
A computer simulation of gas galaxies colliding and merging, ejecting large amounts of gas into "tail tails ". Jeremy Fensch, et al
When star formation disappears, galaxies enterin the later stages of their life (which lasts a few billion years), but how the training stops is a mystery. Some astrophysicists believe that galactic winds caused by black holes or intense star formation could push gas out of a galaxy and extinguish star formation. But new research shows star formation could also be extinguished by these mammoth collisions.
"The gravitational interaction between two galaxies can thus provide sufficient angular momentum to expel part of the gas in the vicinity of the galaxy, " said Annagrazia Puglisi, astrophysicist at the University of Durham and first author of the article.
"This suggests that mergers are also capable of altering the future evolution of a galaxy by limiting its ability to form stars over millions of years and merit further investigation when we think of postmenthat limit the growth of galaxies. "
Puglisi 's team used computer simulations to show that the titanic ejection is likely caused by fusion, rather than black holes or increased star formation in ID2299.
The researchers also suggest that this event could be common in the early universe and that other galactic ejections could be the result of galaxy colliding, calling into question some of the research reports on how winds blow galactic gases in the darkness of space.
To help strengthen the new esis hypothesis, the team will investigate further mergers of distant galaxies and attempt to further limit the possible causes of titanic ejections.
"This could have huge implications for our understanding of what really shapes the evolution of galaxies " said Jeremy Fensch, astrophysicien at the Lyon Astronomical Research Center and co-author of the article.