ALMA Discovers Distant Massive Starburst Galaxies, Peeking into the Early History of the Universe

Astronomers have discovered distant starburst galaxies that were formed early in the universe's history; in fact, they exist earlier than researchers had once thought possible. These findings could help researchers better understand when and how the earliest massive galaxies formed.

Starburst galaxies are the most intense bursts of star birth in our Universe. Thought to have occurred only in the early stages of the Universe, they convert vast reservoirs of gas and dust into new stars at a furious pace--thousands of times faster than spiral galaxies like our own Milky Way. Using the Atacama Large Millimeter/submillimeter Array (ALMA) telescope, astronomers were able to locate these brilliant galaxies.

Although dim in visible light, researchers were able to easily pick out the galaxies in millimeter wavelength light, a portion of the electromagnetic spectrum that the ALMA telescope was designed to explore. Using 16 of ALMA's eventual 66 antennas, the researchers were able to determine the distance of 18 of these galaxies.

What did they find? The galaxies were some of the most distant starburst galaxies ever detected, seen when the Universe was a mere three billion years old. Very few similar galaxies have been discovered at these distances. Researchers are still unsure how these starburst galaxies could have produced so many stars so early in the history of the Universe.

"The more distant the galaxy, the further back in time one is looking, so by measuring their distances we can piece together a timeline of how vigorously the Universe was making new stars at different stages of its 13.7 billion-year history," said Joaquin Vieira, one of the researchers, in a press release.

The findings were possible partially due to the use of gravitational lensing, an effect which occurs when light from a distant galaxy is distorted and magnified by the gravitational force of a nearer galaxy. After analyzing this gravitation distortion, researchers were able to determine that some of the distant star-forming galaxies were as bright as 40 trillion of our suns. The gravitational lensing had magnified this light by up to 22 times.

"This is just the beginning for ALMA and the study of these starburst galaxies," said Daniel Marrone, principle investigator, in a press release. "Our next step is to study these objects in greater detail and figure out exactly how and why they are forming stars at such prodigious rates."

The findings are published in a set of papers in the journal Nature and the Astrophysical Journal.