ALMA Takes Scientists Back in Time to the ‘Golden Age’ of Galaxy Formation

An international team of astronomers has glimpsed a distant corner of the universe, revealing new insights about the "Golden Age" of star formation 10 billion years ago.

The researchers used the Atacama Large Millimeter/submillimeter Array (ALMA) -- a giant radio telescope in Chile -- in exploring a portion of the universe first captured by the Hubble Ultra Deep Field (HUDF). The new ALMA observations are deeper and sharper than previous ones at radio wavelengths, showing how the universe's star formation activity has changed over billions of years.

"This is a breakthrough result," Jim Dunlop from the University of Edinburgh in UK and author of one of the studies, said in a statement. "For the first time, we are properly connecting the visible and ultraviolet light view of the distant universe from Hubble and far-infrared/millimeter views of the universe from ALMA."

In 2004, the Hubble Ultra Deep Field captured images of a tiny, seemingly unremarkable portion of the sky by the constellation Fornax, which revealed a huge collection of glittering galaxies dating back to less than a billion years after the Big Bang. Since then, scientists have been observing this area several times using the Hubble Space Telescope and other observatories to learn more about them.

According to the scientists, the farthest galaxies captured in the Hubble Ultra Deep Field date back to near the beginning of the universe, over 13 billion years ago. With the new observation using ALMA, the researchers conducted a "blind search," focusing on the visible region of space, and discovered a population of galaxies that were not clearly evident in any other deep observations.

ALMA, which is capable of sensing longer wavelengths of light than Hubble, detected galaxies that were primed for star formation. The observations revealed rapidly rising gas carbon monoxide in these galaxies, which are likely behind the remarkable increase in star formation rates during the "Golden Age" of galaxy formation, the researchers said. While Hubble could see stars that already exist, ALMA shows the "missing half" of the galaxy formation and evolution process.

The studies will be published in a series of papers in the Astrophysical Journal and Monthly Notices of the Royal Astronomical Society.