ALMA, the large array of 66 radio telescopes that opened yesterday in Chilé’s Atacama desert, has already helped to discover new starburst galaxies where stars are being born, according to a report today in Nature by a large international team that used the National Science Foundation’s 10-meter South Pole Telescope to discover the ancient galaxies and then switched to ALMA (short for Atacama Large Millimeter/submillimeter Array) for a better look.
If you’re thinking, “hey, these astronomers work pretty fast,” you’re right. The lead author on the Nature paper, California Institute of Technology’s Joaquin Vieira, explained that, “The sensitivity of ALMA allowed us to do in a few minutes per galaxy what used to require hours or even multiple nights.”
However, don’t assume that the astronomers went from opening the doors one night to publishing the next. ALMA actually enjoyed something of a soft opening, and the work was done while the array was still under construction. Only 16 of the radio telescopes were used to help make the discovery of the so-called starburst galaxies, which earn their name because they can be as bright as 40 trillion stars like our sun.
The Nature paper explained that there were 1,000 times as many starburst galaxies in the ancient universe as there are today. Because the universe has continued to expand since it exploded in the original Big Bang, the light the astronomers is studying has traveled for billions of years to reach us. Therefore, despite their brightness, these ancient star-generating galaxies are incredibly distant and hard to see without the use of advanced techniques and telescopes.
The ALMA observatory press release said that the history of the early universe will now have to be rewritten as a result of the team’s discoveries: “Many of these distant dusty star-forming galaxies are even further away than expected. This means that, on average, their bursts of starbirth took place 12 billion years ago, when the Universe was just under 2 billion years old — a full billion years earlier than previously thought.”
Two of the starburst galaxies they discovered first formed when the universe was only one billion years old, and one of the galaxies contained water in its spectrum — which makes it the oldest and most distant water ever detected by humans.
It makes you wonder what the ALMA large space array might discover next.
[Credit: ALMA (ESO/NSAO/NAOJ) and J. Vieira]