The researchers, led by Durham University, said the galaxy created stars similar to our sun, but at as much as 100 times faster than the modern Milky Way -- a rate the equivalent of 250 suns per year.
The study's lead author, Mark Swinbank of Durham University's Institute for Computational Cosmology, said, "This galaxy is like a teenager going through a growth spurt."
Due to the amount of time it takes light to reach Earth, the scientists said they are observing the galaxy as it would have appeared 10 billion years ago -- just 3 billion years after the Big Bang.
"We don't fully understand why the stars are forming so rapidly but our results suggest that stars formed much more efficiently in the early universe than they do today," Swinbank said.
The research is reported in the online early edition of the journal Nature.