Early Star Forming Galaxies
April 17, 2013

ALMA Telescope Helps Detail Early Star-Forming Galaxies

Lee Rannals for redOrbit.com - Your Universe Online

Astronomers report in The Astrophysical Journal that they have determined the positions of over 100 of the most fertile star-forming galaxies in the early Universe.

The group used the new Atacama Large Millimeter/submillimeter Array (ALMA) telescope during their observations. This telescope can capture just as many observations of this group of galaxies in just a few hours as similar telescopes can in more than a decade.

[ Video: Zooming in on Early Star-Forming Galaxies ]

“Astronomers have waited for data like this for over a decade. ALMA is so powerful that it has revolutionized the way that we can observe these galaxies, even though the telescope was not fully completed at the time of the observations,” said Jacqueline Hodge (Max-Planck-Institut für Astronomie, Germany), lead author of the paper presenting the ALMA observations.

The Atacama Pathfinder Experiment (APEX) telescope surveyed a patch of sky about the size of the full Moon in the southern constellation of Fornax and detected 126 of these fertile galaxies. However, each burst of star formation viewed by APEX appeared as a fuzzy blob. The team used ALMA to observe the galaxies from the APEX map of these distant galaxies during the first phase of scientific observations while ALMA was still under construction.

[ Video: Comparing APEX and ALMA Views of Star-Forming Galaxies ]

It only took ALMA two minutes per galaxy to pinpoint each of the star forming regions within an area 200 times smaller than the broad APEX blobs, and with three times the sensitivity. Not only was the team able to identify which galaxies had regions of active star formation, but they also found that multiple star-forming galaxies had blended into a single blob in the APEX map.

“We previously thought the brightest of these galaxies were forming stars a thousand times more vigorously than our own galaxy, the Milky Way, putting them at risk of blowing themselves apart. The ALMA images revealed multiple, smaller galaxies forming stars at somewhat more reasonable rates,” said Alexander Karim, of Durham University and a member of the team and lead author of a companion paper on this work.

This study is the first reliable catalogue of dusty star-forming galaxies in the early Universe. It is providing a vital foundation for future research of these galaxies' properties at different wavelengths.