Gravitational Lensing Used To Seek Out Most Distant, Active Star Forming Galaxies
May 29, 2013

12 Billion Year Old Galaxies Discovered: ALMA

Lee Rannals for - Your Universe Online

Scientists working with the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered the most distant and active star forming galaxies in our universe.

The astronomers wrote in the journal Nature and Astrophysical Journal that they discovered these distant and enigmatic galaxies after surveying large areas of the sky with the 10-meter South Pole Telescope. They used ALMA to help them obtain higher resolution images.

The team used an observing technique known as gravitational lensing. This effect takes place when the light of a distant galaxy is deflected by the gravitational influence of a nearer foreground galaxy. In order for this to happen, the distant galaxy has to be nearly perfectly located behind the lens galaxy.

“Only a few gravitationally lensed galaxies had been previously studied at submillimeter wavelengths,” said Gil Holder, from McGill University and one of the co-authors. “The new high resolution observations with ALMA have provided new views of tens of such systems.”

The team carried out a second survey with ALMA to observe light from carbon monoxide molecules inside these galaxies to measure their distances from Earth. The team found that many of the galaxies were consistently farther away than they anticipated, including a few nearly 12 billion light years away.

Some of the distant star-forming galaxies are as bright as 40 trillion Suns, forming about 4,000 new stars per year just a billion years after the Big Bang.

“We want to understand how and why these galaxies are forming stars at such incredibly fast rates, so soon after the Big Bang.” said Scott Chapman, from Dalhousie University and one of the co-authors. “This could partially answer how our own galaxy, the Milky Way, was born billions of years ago.”

Mysterious dark matter could explain what helped the astronomers obtain the gravitational lensing effect images.

”Gravitational lensing allows us to measure the distribution of dark matter in the lensing galaxies in great detail. These types of studies were previously only possible at visible-light wavelengths with the Hubble Space Telescope, but now our results show that, thanks to ALMA, gravitational lensing studies in the submillimeter domain have entered a new phase.” said Yashar Hezaveh, from McGill University. “In the future, we will study the distribution of dark matter in the lensing galaxies with unprecedented detail."

Results of this research were also presented at the annual meeting of the Canadian Astronomical Society in Vancouver, British Columbia on Tuesday.