Scientists peeled back 12 billion years of cosmic history to reveal a startling detail about a young galaxy’s early formation.
(CN) — To help us understand how galaxies formed after the Big Bang, scientists probed the edges of the universe using an extraordinary research method: they went back in time, according to a study released Thursday.
Images of the distant galaxies spread across the cosmos communicate important information about their size, age and other details that help us classify whether they’re spiral, elliptical or other types of galaxies. Our own galaxy, the spiral Milky Way, is one of at least 2 trillion known galaxies in the observable universe.
But portraits of the clusters of stars, gas and dark matter also help us understand how massive fields of gases, radiation and stardust collided after the Big Bang and ignited the heavens we know today.
How exactly galaxies formed is a topic of debate, but we know that around 400 million years after the Big Bang — the powerful event 13.8 billion years that marked the beginning of the known universe — galaxies began populating the sky.
To better understand early galaxy formation, a research team led by scientists at Cardiff University in Wales set their sights on a galaxy called ALESS 073.1.
Researchers sought to analyze why galaxies vary in size and color and why some feature large bulges and spiral arms while others may be thin or contain rotating disks.
The team used a powerful telescope to complete the feat.
The Atacama Large Millimeter/submillimeter Array (ALMA) project — a collection of dozens of radio telescopes peering at the heavens from a northern Chilean desert — was pointed at the stars.
Using ALMA as a sort of time machine, scientists were able to see how ALESS 073.1 would have appeared 1.2 billion years after the Big Bang.
The image revealed a relatively young galaxy — formed in the early stages of the universe — that, for its age, had the features of a much more mature galaxy, according to the study published Thursday in the journal Science.
The youthful portrait was only possible because light emitted by the galaxy took billions of years to reach ALMA’s telescopes.
Crisp images of the primordial galaxy allowed researchers to analyze its structure and its so-called “bulge” or tight cluster of stars. The presence of a bulge typically signifies that the cluster of stars built up internally over time or that a slow merger of other smaller galaxies occurred over billions of years.
But the properties of the ALESS 073.1 bulge showed that it formed much more quickly than others, the study said.
Lead author Federico Lelli of Cardiff University in the U.K. said in a statement released with the study that researchers were perplexed when they found the young galaxy had features consistent with much older galaxies.
“We discovered that a massive bulge, a regular rotating disk, and possibly spiral arms were already in place in this galaxy when the universe was just 10% of its current age,” Lelli said. “In other words, this galaxy looks like a grown adult, but it should be just a little child. A galaxy like ALESS 073.1 just defies our understanding of galaxy formation.”
The study also revealed that at least half the stars in ALESS 073.1 were part of a bulge.
Study co-author Timothy Davis of Cardiff University said in the statement the team was surprised to see mature attributes in ALESS 073.1 since young galaxies were thought to contain less organized structures.
“This spectacular discovery challenges our current understanding of how galaxies form because we believed these features only arose in ‘mature’ galaxies, not in young ones,” Davis said.
Researchers did not immediately respond to a request for further comment on the study.