ALMA arrives with discovery of monster starburst galaxies at the edge of time

NEW DELHI: ALMA has arrived with a bang! Scientists at the Atacama Large Millimeter/submillimeter Array (ALMA), an observatory located in one of the coldest, driest places on earth, have found a monster starburst galaxy with the brightness of 40 trillion Suns. It is located at an unimaginable distance - light seen by ALMA started from the galaxy some 12.7 billion years ago when the Universe was just a billion years old.Scientists found that it was giving birth to new stars at a mind boggling rate of 1000 every year. Our galaxy, the Milky Way gives birth to one star every year.
Actually ALMA found a whole zoo of galaxies, some 18 of them, all of them from the early turbulent period of the Universe when it was one to three billion years old. Usually, star formation from gigantic swirling clouds of dust does not take place at such a furious pace as in these ancient galaxies.
The research is the most recent example of the discoveries coming from the new international ALMA observatory, which celebrates its inauguration today. The international team of researchers first discovered these distant starburst galaxies with the National Science Foundation's 10-meter South Pole Telescope. Though dim in visible light, they were glowing brightly in millimeter wavelength light, a portion of the electromagnetic spectrum that the new ALMA telescope was designed to explore.
Using only 16 of ALMA's eventual full complement of 66 antennas, the researchers were able to precisely determine the distance to 18 of these galaxies, revealing that they were among the most distant starburst galaxies ever detected. These results were surprising because very few similar galaxies had previously been discovered at similar distances, and it wasn't clear how galaxies that early in the history of the Universe could produce stars at such a prodigious rate.
The results, published in a set of papers to appear in the journal Nature and in the Astrophysical Journal, will help astronomers better understand when and how the earliest massive galaxies formed. The most intense bursts of star birth are thought to have occurred in the early Universe in massive, bright galaxies. These starburst galaxies converted vast reservoirs of gas and dust into new stars at a furious pace - many thousands of times faster than stately spiral galaxies like our own Milky Way.
"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 of Caltech who led the team and is lead author of the Nature paper, as reported in a statement by the National Radio Astronomy Observatory in the US.
Intriguingly, emission from water molecules was detected in one of these record-breakers, making it the most distant detection of water in the Universe published to date.
"ALMA's sensitivity and wide wavelength range mean we could make our measurements in just a few minutes per galaxy - about one hundred times faster than before," said Axel Weiss of the Max-Planck-Institute for Radioastronomy in Bonn, Germany, who led the work to measure the distances to the galaxies, the NRAO statement said. "Previously, a measurement like this would be a laborious process of combining data from both visible-light and radio telescopes."
ALMA was able to measure all this because of gravitational lensing, in which the light from a distant galaxy is distorted and magnified by the gravitational force of a nearer foreground galaxy. Analysis of this gravitational distortion reveals that some of the distant star-forming galaxies are as bright as 40 trillion Suns, and that gravitational lensing has magnified this light by up to 22 times.
ALMA, an international astronomy facility, located in the Atacama desert where there is minimal interference from light and dust. ALMA construction and operations are led on behalf of Europe by ESO, on behalf of North America by the National Radio Astronomy Observatory (NRAO), and on behalf of East Asia by the National Astronomical Observatory of Japan (NAOJ).