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Astroboffins spot a new type of galaxy bursting with stars

Star formation rate is a hundred times faster than our Milky Way

Artist's impression of a bright quasar and a two galaxies merging nearby (Image credit: Max Planck Institute for Astronomy and NASA/ESA Hubble Space Telescope)

A team of astronomers has stumbled across a new kind of galaxy that may be the missing piece of the puzzle regarding how ancient galaxies grew to such massive sizes.

There is a strange population of galaxies that formed when the universe was less than 2 billion years old compared to the current estimated age of around 14 billion. These galaxies are surprisingly hefty and full of swirling cocktails of gases and stars.

Some scientists think that they must have spawned from a group of hyperactive precursor galaxies that led to unusually fast rates of star formation. But these types of galaxies had not been found until now.

The team has described their discovery as “serendipitous.” They were analyzing the rate of star development around quasars when they made the discovery.

Quasars are highly energetic and bright. It is widely believed that their energy comes from supermassive black holes located in the middle of nearby galaxies, pulling in surrounding material.

“But what we found, in four separate cases, were neighboring galaxies that were forming stars at a furious pace, producing a hundred solar masses’ worth of new stars per year,” said Roberto Decarli, lead author of the paper published in Nature and researcher at the Max Planck Institute for Astronomy.

These galaxies pump out stars a hundred times faster than the Milky Way. It’s probably not a coincidence that they were spotted near quasars, according to Fabian Walter, co-author of the paper and a researcher also at the Max Planck Institute for Astronomy.

“Quasars are thought to form in regions of the universe where the large-scale density of matter is much higher than average. Those same conditions should also be conducive to galaxies forming new stars at a greatly increased rate,” he explained.

They are promising candidates to explain how old galaxies with large redshifts grew to such large sizes, but further study is needed to piece these two together.

“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 Bañados, co-author of the paper and researcher at the Carnegie Institution for Science.

“This is just a little step towards the understanding of how the first galaxies formed. This is critical, as what happened in the early universe is what finally shaped the universe we currently live in,” Bañados told The Register ®.

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