ALMA Telescope Discovers Oldest Merging Galaxies Ever

Galaxies merging isn't something that is uncommon, according to scientists. Galaxy mergers are something that scientists want to study in an effort to piece together how galaxies evolve. Radio astronomers using the Atacama Large Millimeter/submillimeter Array (ALMA) have discovered the oldest known merging galaxies.

The merging galaxies are called B14-65666 and are 13 billion light-years away in the constellation Sextans. The light that we see now left the galaxies 13 billion years ago. Scientists say that is shortly after the beginning of the universe.

While this is the first time that ALMA has studied B14-65666, the Hubble Space Telescope spotted the object but had classified B14-65666 as two separate objects. Hubble believed they were likely star clusters. ALMA did confirm that B14-65666 is a pair of merging galaxies, not separate star clusters.

The scientists noted that Hubble was limited to viewing the object in the UV spectrum, which is what made it appear as two star clusters. The ALMA team noted telltale fingerprints of chemical elements in its observations. ALMA was able to see radio wave emissions of carbon, oxygen, and dust in the object, and those were keys to figuring out what the team was looking at.

Further analysis showed that the object has two parts, just as Hubble noted. ALMA has shown the two blobs are distinct but form a single system. The study has shown that the object is the earliest-known example of a galaxy merger. The total stellar mass of B14-65666 is estimated to be less than 10% of the Milky Way's mass indicating it was in the earliest stages of its evolution, which the team says makes sense considering how ancient it is. Readings did suggest that the object was very active in star formation.