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B. Saxton (NRAO/AUI/NSF); ALMA (ESO/NAOJ/NRAO); NASA/ESA Hubble

Take a deeper look. New observations of a distant corner of the universe add a layer to our understanding of the early universe.

Teams of international astronomers used a powerful telescope called the Atacama Large Millimetre/submillimetre Array (ALMA) to exploreHubble Ultra Deep Field (HUDF) images from the Hubble telescope showing more than 10,000 galaxies in one tiny portion of the sky.

They show how the rate of star formation in young galaxies is closely related to their total mass in stars. They also trace the previously unknown abundance of star-forming gas at different points in time, providing new insights into the “Golden Age” of galaxy formation approximately 10 billion years ago.

The studies, which appear in the Astrophysical Journal and Monthly Notices of the Royal Astronomical Society, are being hailed as the deepest ever millimetre observations of the early universe.

Astronomers used ALMA – which, with 66 high precision antennae, is currently the world’s largest array – to survey this area for the first time in the millimetre range of wavelengths, allowing them to see the faint glow from gas clouds and the emission from warm dust in galaxies in the early universe. The array observed the HUDF for a total of around 50 hours.

“For the first time, we are properly connecting the visible and ultraviolet light view of the distant universe from Hubble and far-infrared/millimetre views of the universe from ALMA,” says Jim Dunlop at Edinburgh University, who describes it as a “breakthrough result”.

“Through this, we discovered a population of galaxies that is not clearly evident in any other deep surveys of the sky,” says Chris Carilli at the National Radio Astronomy Observatory (NRAO) in New Mexico.

“The new ALMA results imply a rapidly rising gas content in galaxies as we look back further in time,” says Manuel Aravena at the Universidad Diego Portales in Chile. “This increasing gas content is likely the root cause for the remarkable increase in star formation rates during the peak epoch of galaxy formation, some 10 billion years ago.”

And this may be just the start of enlightening insights from ALMA. The array will make a 150-hour observation of the HUDF in the future.

Quelle: New Scientist