A team of researchers has discovered the most distant rotating massive disk galaxy ever observed. Although galaxies similar to the Milky Way are common throughout the Universe, one as large and as old as this one has never been discovered.
Named for Wolfe Disk, in honor of the late astronomer Arthur M. Wolfe, the galaxy DLA0817g rotates at 272 kilometers per second and weighs 72 billion times the mass of the Sun.
This is the oldest disk galaxy ever found: it formed when the Universe was 10% of its current age. The observations, conducted by the Atacama Large Millimeter / submillimeter Array (SOUL), clash with traditional models who argue for a massive disk galaxy like this to form about six billion years after the Big Bang, which is not so soon.
"Although previous studies have suggested the existence of these gas-rich, rotating disk galaxies, thanks to ALMA, we now have unequivocal evidence that they occur 1.5 billion years after the Big Bang," he said. Marcel Neeleman, from the Max Planck Institute of Astronomy and lead author of the study, in communication.
According to New Scientist, this may mean that galaxies like the Milky Way may have started to form much earlier in the history of the universe than we thought.
Galaxies are believed to form through many smaller galaxy fusions, as well as capturing hot clusters of gas. The process is chaotic and leads to a confused galaxy that only becomes a more orderly object after billions of years.
However, another mechanism will be needed to explain the formation of this strange and rebellious galaxy. “We believe that Wolfe Disk has grown mainly through the constant accumulation of cold gas“, Explained the co-author J. Xavier Prochaska, from the University of California. "Still, one of the remaining questions is how to assemble such a large mass of gas, while maintaining a relatively stable rotating disk."
According to the study published this month in the scientific journal Nature, the galaxy is forming stars at a 10 times higher rate than our own galaxy. This is one of the highest rates during that time in the Universe, but far from the highest ever.
The galaxy was first discovered in 2017, while the team studied the light of a distant luminous quasar, a specific type of active galaxy. The quasar emission was altered by the large hydrogen cloud around the Wolfe Disk, allowing the discovery of a much weaker galaxy.
“The fact that we found the Wolfe Disk using this method it tells us that it belongs to the normal population of galaxies present in the early days, ”said Neeleman. “When our most recent observations from ALMA surprisingly showed that it is spinning, we realized that galaxies on a primitive rotating disk are not as rare as we thought and that there must be many more out there. ”