Astronomers have used the Atacama Large Millimeter/submillimter Array (ALMA) telescope to more accurately map dusty star-forming galaxies in the early Universe. The new telescope is significantly more powerful than other similar devices, and in just a few hours, using less than a quarter of its full capacity, was able to double the number of confirmed observations of this type.

The study of ancient star-forming galaxies is of paramount importance to our understanding of the birth and evolution of stars. However, the distant and dusty nature of the galaxies makes it difficult to accurately observe them with visible light telescopes. To solve the problem, astronomers have to use telescopes that detect light at longer wavelengths of around one millimeter.

The ESO's Atacama Pathfinder Experiment telescope (APEX) is one such device, and has, in the past, been used to observe the same star-forming galaxies seen in the ALMA observations. The device has a single 12-meter (39.4-foot) diameter dish-shaped antenna, and though it detected 126 of the early galaxies, the images it produced were fuzzy, making it difficult to accurately distinguish the galaxies from one another.

Unlike the APEX telescope, ALMA uses multiple dishes spread over wide distances, combining the signals to create images that are over 200 times more accurate than those from the older device. In just a few hours, the telescope was able to double the total number of such observations made. What's even more impressive is that at the time the observations were made, ALMA was using less than a quarter of its full complement of 66 antennas.

The red circle here shows the location of the galaxies in the southern constellation of Fornax (Image: ESO)

With the greater accuracy of ALMA, the team was able to pinpoint the locations of the galaxies. In many cases, the single fuzzy blobs found by APEX were actually identified as multiple star-forming galaxies.

It was previously thought that the blobs were giant star-forming galaxies at risk of blowing themselves apart, but ALMA's readings clarify our understanding, lowering the formation rate in those galaxies to a more reasonable pace.

“Astronomers have waited for data like this for over a decade," stated Jacqueline Hodge, lead author of the ALMA observations paper. "ALMA is so powerful that it has revolutionized the way that we can observe these galaxies.”

The new readings provide a reliable catalog of star-forming galaxies in the early Universe and act as a strong foundation for further research into the field, allowing future studies to be carried out with a significantly lower risk of misinterpretation.

Source: ESO