Today is inauguration day for ALMA, the massive telescopic array that’s still under construction in Chile’s Atacama Desert. But just because it’s not finished doesn’t mean astronomers haven’t been using it. The $1.5 billion telescope has just peered into the deepest realms of the universe, revealing some of the most distant star-spawning galaxies ever discovered.
Once complete, the ALMA array will employ 66 antennas — but 16 antennas were all an international team of researchers needed to perform this initial scan. By using the gravitational lensing technique (in which the light from a distant galaxy is distorted and magnified by the gravitational force of a nearer foreground galaxy), the astronomers were able to catch a glimpse of the universe’s most primordial galaxies.
Image: Gravitational lensing explained. Some distant starburst galaxies are as bright as 40 trillion suns, and have been magnified by the gravitational lens by up to 22 times. Credit: ALMA (ESO/NRAO/NAOJ), L. Calçada (ESO), Y. Hezaveh et al.
The astronomers honed in on 26 potential starburst galaxies — massive, bright, and dusty galaxies that appeared during the early phases of the universe’s history. It was within these ancient and highly energetic galaxies that vast reservoirs of dust and gas were converted into new stars — and at a pace that’s many thousands of times faster than what’s typically seen today. At their peak, and as the new research shows, starburst galaxies could produce upwards of 10,000 stars each year.
These 26 lensed galaxies were initially discovered by astronomers using the National Science Foundation's 10-meter South Pole Telescope (SPT). But it was ALMA that allowed astronomers to obtain more detailed imaging and spectroscopic data. By using ALMA, they were able to increase the apparent luminosity of the galaxies by a factor of 10 — doubling the number of starburst galaxies known to exist in the high-redshift universe).
Above image: A lensed starburst galaxy. The distant galaxy is shown in red, and it's distorted by the gravitational lens effect produced by the galaxy in front of it (shown in blue). The background galaxy is warped and has taken on the form of an Einstein ring, a circle of light around the foreground galaxy. Credit: Dan Marrone.
The results of the survey, which now appear in Nature and in the Astrophysical Journal, show that these starburst galaxies are much further away than previously assumed — about 12 billion light years away to be exact. This means that rapid star formation began a mere two billion years after the Big Bang. That's a full one billion years earlier than the previous estimate.
The research also shows that early starburst galaxies were more abundant than previously thought.
One of the galaxies discovered was already in existence a mere one billion years after the birth of the universe, its light travelling the length of the cosmos since that time.
Interestingly, the astronomers also detected water molecules in the same galaxy, which now makes it the earliest observation of water ever made.
Here's a link to the study at Nature.
Top image: Stephane Guisard/ESO.