Research teams have turned to the Atacama Large Millimeter/Submillimeter Array (ALMA) to explore the Hubble Ultra Deep Field (HUDF), achieving a deeper, sharper look at an already-well-studied area in the sky.
Presented at the Half a Decade of Alma conference, the results of these explorations will be published in a series of studies in the Monthly Notices of the Royal Astronomical Society and the Astrophysical Journal.
The HUDF images, first published in 2004, were captured using the Hubble Space Telescope. As the deepest probes at the time, the pictures unveiled a collection of galaxies that stretch as far back as less than a billion years after the Big Bang event occurred.
Now, using ALMA to aid them, astronomers dared to probe even further. The HUDF is already a heavily studied portion of the sky, but this is the first time that the early universe was observed at millimeter wavelengths.
Specifically, the Fornax (The Furnace) region of the HUDF was chosen by the astronomers for their research. Some 50 hours were logged for the HUDF observations, the longest period of time spent, so far, observing any part of the sky.
In one of the studies, researchers led by University of Edinburgh's Jim Dunlop used the ALMA telescope to come up with the first deep and homogeneous image of a space region of the same size as the HUDF, which allowed for matching galaxies that have already been detected using other facilities like Hubble.
This particular research also clearly showed for the first time that a galaxy's stellar mass best predicts the rate of how often and how quickly stars are formed in a universe registering an increase in wavelength but a decrease in frequency in electromagnetic waves.
According to Dunlop, their results were a breakthrough because they were properly able to connect for the first time the ultraviolet and visible light views from Hubble and millimeter/far-infrared views from ALMA of the early universe.
Another study, headed by Manuel Aravena, focused instead on a deeper search in just a sixth of the HUDF. According to research team member Chris Carilli, their work was the first fully blind, three-dimensional search for cool gas within the early universe. It's called a "blind" search because it is not focused on a particular object.
Some of the newer observations achieved through ALMA were particularly geared toward detecting galaxies filled with carbon monoxide. These galaxies are often difficult to spot with Hubble so the use of ALMA can reveal many new things that have not been observed before.
In the future, a 150-hour observation of the HUDF is planned to further get a better look at the universe's star-forming history.
