New Delhi:
Extremely old galaxies which were formed less than a billion years after the Big Bang, have been discovered by scientists. Stars are created by the galaxies in a much faster way than our own Milky Way.
The cosmic conundrum of mysterious population of shockingly huge galaxies from the time when the universe was only about 10 per cent of its present age, could also be eased out with the discovery.
When the astronomers observed these galaxies a few years ago, they suggested that the galaxies must have been created from hyper-productive precursor galaxies, which is the only way so many stars could have formed so quickly.
However, astronomers had never seen anything that fit the bill for these precursors until now.
This newly discovered population could solve the mystery of how these extremely large galaxies came to have hundreds of billions of stars in them when they were formed only 1.5 billion years after the Big Bang, requiring very rapid star formation.
This discovery was made by the researchers led by Roberto Decarli of Max Planck Institute for Astronomy. The discovery happened by accident when the astronomers were investigating quasers. Quasers are supermassive black holes found at the centre of enormous galaxies, accreting matter.
They were trying to study star formation in the galaxies that host these quasars.
"But what we found, in four separate cases, were neighbouring galaxies that were forming stars at a furious pace, producing a hundred solar masses' worth of new stars per year," Decarli said.
"Very likely it is not a coincidence to find these productive galaxies close to bright quasars. Quasars are thought to form in regions of the universe where the large-scale density of matter is much higher than average," said Fabian Walter, from Max Planck Institute for Astronomy.
"Those same conditions should also be conducive to galaxies forming new stars at a greatly increased rate," Walter said.
"Whether or not the fast-growing galaxies we discovered are indeed precursors of the massive galaxies first seen a few years back will require more work to see how common they actually are," said Eduardo Banados from Carnegie Institution for Science in the US.
The team also found what appears to be the earliest known example of two galaxies undergoing a merger, which is another major mechanism of galaxy growth.
The new observations provide the first direct evidence that such mergers have been taking place even at the earliest stages of galaxy evolution, less than a billion years after the Big Bang.
(With PTI inputs)
