Recently Discovered Protogalaxy Hints How Early Universe Was Formed
Astronomers led by Caltech discovered a giant swirling discoid of gas 10 billion light-years away from Earth. The phenomenon is called a protogalaxy by scientists. It is a developing galaxy fed by a string of gas tracing back to the beginning of the universe. The discovery provides evidence for a newer theoretical model of galaxy creation.
Caltech’s Cosmic Web Imager (CWI) at Palomar Observatory – northeast of San Diego – imaged the protogalaxy. The observers discovered a link to what they call “the intergalactic medium”, or “cosmic web”, comprised of gases that flow throughout the universe. It appeared this link was feeding the nascent galaxy. The discovery bolsters evidence for the cold-flow model of galaxy formation.
The cold-flow model states that, in the incipient universe, cool gas entered into galaxies from the cosmos, leading to rapid star formation. The science journal Nature will publish these findings in their August 13 issue.
“This is the first smoking-gun evidence for how galaxies form,” notes Christopher Martin, professor of physics at Caltech, lead author of the new paper.
Even as simulations and theoretical work have increasingly stressed the importance of cold flows, observational evidence of their role in galaxy formation has been lacking.
The swirling gas is approximately 400,000 light-years across, according to the researchers.
“The images plainly show that there is a rotating disk—you can see that one side is moving closer to us, and the other is moving away. And you can also see that there’s a filament that extends beyond the disk,” Martin says. The disk rotates at approximately 400 kilometers per second, the researchers stated.
“The filament has a more or less constant velocity. It is funneling gas into the disk at a fixed rate,” says paper co-author Matt Matuszewski. “Once the gas merges with the disk inside the dark-matter halo, it is pulled around by the rotating gas and dark matter in the halo.”
The cold flow model contrasts with an older theory of galaxy formation, which states that as so-called “dark-matter halos” buckles, extremely high temperatures are produced before the gas slowly cools and forms new galaxies. Scientists scrutinize that model due to its inability to explain certain aspects of the phenomenon. The cold-flow model could provide a solution.
“That’s a direct prediction of the cold-flow model, and this is exactly what we see—an extended disk with lots of angular momentum that we can measure,” says Martin. The team has discovered two separate discoids that behave in the same manner.
Featured image from Shutterstock.