ALMA Captures more than 100 Ancient Star-Forming Galaxies

With the help of the new Atacama Large Millimeter/submillimeter Array (ALMA) telescope, a team of astronomers have pinpointed locations of over 100 of the most fertile star-forming galaxies in the early universe.

The new ALMA is so powerful that within a few hours it captured many observations of the galaxies. Similar telescopes would take over a span of more than a decade to capture the same observations as made by ALMA.

The fertile bursts of star birth in the early universe occurred in distant galaxies that had enormous cosmic dust, which makes them look vague and difficult to study at the same time. These galaxies are crucial as they help in understanding galaxy formation and how it evolved. For such observations, astronomers use a telescope that can observe light even at a longer wavelength, such as ALMA.

According to Jacqueline Hodge of the Max-Planck-Institut für Astronomie, Germany, lead author of the paper presenting the ALMA observations, ALMA has changed the way galaxies can be observed even though the construction of the telescope was not complete at the time the observations were made.

Till date, the Atacama Pathfinder Experiment telescope (APEX) had provided the best map of the distant dust galaxy. Nearly 126 galaxies were discovered from a patch of sky that is the size of the moon. The images APEX provided were hazy. APEX uses a 12-meter diameter whereas ALMA uses several APEX-like dishes that are spread over a wide area.

With the help of ALMA, astronomers are observing the galaxies captured by APEX in the Apex map.  ALMA took a minimum of two minutes per galaxy to pinpoint each galaxy that was located in a small area which is 200 times smaller when compared to the APEX blobs. ALMA is three times more sensitive than other telescopes. Astronomers were able to differentiate between separate galaxies with ALMA.

"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," Alexander Karim of Durham University in the United Kingdon, who was also associated with the research, said in a press statement. "The ALMA images revealed multiple, smaller galaxies forming stars at somewhat more reasonable rates." 

This research will appear in the Astrophysical Journal.