Astronomers say they are close to solving an intergalactic mystery about the creation of the universe's biggest galaxies which has puzzled experts for decades.
Scientists have discovered the birth sites of gigantic elliptical galaxies which they claim offer new clues about how they were formed.
The creation of these ancient galaxies, which look like bulging footballs compared to our flat disk-like Milky Way, remains a mystery to astrophysicists.
But now academics from the University of Southampton, working with experts across the world, say their new study may finally unravel the enigma.
Dr Annagrazia Puglisi from Southampton, who co-authored the research, said it is likely that large flows of cold gas and collisions between galaxies in the early universe created these giant systems.
She added: "Two disk galaxies smashing together caused gas – the fuel from which stars are formed – to sink towards their centre, generating trillions of new stars.
"These cosmic collisions happened some eight to 12 billion years ago, when the universe was in a much more active phase of its evolution.
"Our findings take us closer to solving a long-standing mystery in astronomy that will redefine our understanding of how galaxies were created in the early universe."
The study, published in Nature, was a collaboration between Southampton, the Purple Mountain Observatory in China and the Chinese Academy of Science, among others.
Experts analysed more than 100 star-forming galaxies in the distant universe using the world's largest radio telescope, known as ALMA, located in Chile's Atacama desert.
The scientists made the discovery using a new technique which looked at the distribution of light emitted by distant and highly-luminous galaxies, said study lead Dr Qing-Hua Tan from the Purple Mountain Observatory.
She added: "This is the first real evidence that spheroids form directly through intense episodes of star formation located in the cores of distant galaxies.
"Astrophysicists have sought to understand this process for decades.
"These galaxies form quickly – gas is sucked inwards to feed black holes and triggers bursts of stars, which are created at rates ten to 100 times faster than our Milky Way."
Researchers used the open-source A3COSMOS and A3GOODSS archival projects which enabled them to gather high-quality observations of many distant galaxies.
The scientists say they will combine their findings with data taken from telescopes aboard the JWST and Euclid satellites, as well as the Chinese Space Station, to map the stellar components of galaxies.
Dr Puglisi from Southampton added: "This will give us a more complete picture of early galaxy formation and deepen our understanding of how the universe has evolved since the beginning of time."
