Astronomers have found the oldest and the farthest galaxy which is tipped to challenge the current theory of how galaxies are formed during the early universe. As of current, studies have shown that these massive systems which consist of stars, gases, and dust took their shape in a slow and steady manner over a period of billions of years.
It is a huge rotating disk galaxy in the distant universe. According to researchers at Atacama Large Millimeter/submillimeter Array (ALMA) Observatory in Chile, the massive rotating disk galaxy was formed at least 12.5 billion years ago when our universe was only a tenth of its current age. However, the new discovery is challenging how astronomers perceive the concept of galaxy formation. Astronomers say the galaxy is “unambiguous evidence” and that such massive galaxies existed only 1.5 billion years after the Big Bang, which is in dispute of current models of galaxy formation.
Nicknamed ‘Wolfe Disk’ after the late astronomer Arthur M. Wolfe, the Galaxy DLA0817g was discovered by the Atacama Large Millimeter/submillimeter Array (ALMA) in 2017. However, a newly found “DLA0817g” galaxy which is called Wolfe Disk has been shown to have taken the shape of a disk at an early stage. Although the universe is 13.8 billion years old, galaxies did not shape up soon after. The current shape is the result of a slow and steady change. According to published research, the ‘most distant rotating disk’ is spinning at 272kms per second and is similar to the Milky Way in its shape.
The research said, “The discovery of the Wolfe Disk provides a challenge for many galaxy formation simulations, which predict that massive galaxies at this point in the evolution of the cosmos grew through many mergers of smaller galaxies and hot clumps of gas.”
Scientists happened to find the galaxy while observing the light from a distant quasar that passed through the cloud of hydrogen gas surrounding the disk galaxy. This is an observation method where astronomers use bright lights from rarer galaxies to find fainter galaxies ‘normal’ galaxies in the early universe.
The researchers have also observed the mass of the Wolfe Disk is 70 billion times of our sun. Researchers have believed that stable galaxies like Milky Way with structured disk were formed six billion years after the Big Bang. However, the new observation is an “unambiguous” proof that galaxies were formed 1.5 billion years after the phenomenon, according to lead author Marcel Neeleman of the Max Planck Institute for Astronomy in Heidelberg, Germany.
“While previous studies hinted at the existence of these early rotating gas-rich disk galaxies, thanks to ALMA we now have unambiguous evidence that they occur as early as 1.5 billion years after the Big Bang,” said lead author Marcel Neeleman.
The discovery of the Wolfe Disk goes against various galaxy simulations that hypothesize the formation of galaxies that predict that in the early universe, massive galaxies formed by mergers of smaller galaxies and hot clumps of gas. The reason – well it’s because these mergers were pretty violent and resulted in galaxies.
Researchers think that Wolfe Disk grew mainly because of steady accretion of cold gas but as Co-author J. Xavier Prochaska from the University of California, Santa Cruz says, “Still, one of the questions that remains is how to assemble such a large gas mass while maintaining a relatively stable, rotating disk.