South Africa’s MeerKAT Detects a Distant Galaxy with Large Hydrogen Atoms

Source: SARAO

The South African Radio Astronomy Observatory (SARAO) has announced that the MeerKAT discovered a distant galaxy towards PKS 1830-211, with some of the largest hydrogen atoms in the universe. This announcement was covered in a press release detailing the distant galaxy located in the Sagittarius constellation PKS1830-211, a distant quasar 11.1 billion light years away. The hydrogen atoms were discovered when light from the quasar travels through a prominent galaxy with a 7.3 billion light-years distance. The light elucidates the molecular chemistry of the galaxy, allowing the large hydrogen atoms to be studied and investigated. 

MeerKat, a radio telescope designed to discover distant galaxies, detected the Rydberg atom augmented by radio light. However, locating the atoms under favourable conditions in distant galaxies has remained a mystery. However, the MeerKAT Absorption Line Survey (MALS), dedicated to observing and detecting the brightest radio points in the sky, is most sensitive in locating signatures from hydrogen atoms, large Rydberg atoms and molecules.

“We used hydrogen Rydberg atoms to study the physical and dynamic structures in a galaxy 7.3 billion light years away towards PKS 1830-211. The Rydberg atoms could be coming from large clouds of gas that are ionised by the radiation from young massive stars. These atoms tell us that interstellar gas in this galaxy is much denser than what is found in the Milky Way,” commented Kimberly Emig, a Jansky Fellow at the National Radio Astronomy Observatory (NRAO), USA and lead author of the paper.

Furthermore, Lead Author Kimberly Emig explained the discovery as a different perspective of understanding the universe and researching the progression of observed interstellar gas in our known galaxies through time. According to Emig, “They could also help us to understand how interstellar gas drives and inhibits the activity of supermassive black holes.”

The MALS survey majorly utilised a transition of atomic hydrogen at 21 cm wavelengths and shifts from the hydroxyl (OH) molecule at 18 cm wavelengths to locate instances of atomic and molecular gas near galaxies. 

A global team of researchers from India, Europe, North America, and Australia manage the MeerKAT Absorption Line Survey. Furthermore, observations from the survey are processed by the National Radio Astronomy Observatory, Inter-University Centre for Astronomy and Astrophysics (IUCAA), and ThoughtWorks Technologies India Pvt Ltd and their partners.

“Only a small number of these transitions have been detected in distant galaxies so far due to technical limitations. However, if we detect a large number (several 100) of these transitions, we can assess the physical conditions of cold gas, which serves as fuel for star formation in galaxies. Nevertheless, studying ionised gas through hydrogen Rydberg atoms complements interstellar gas in its atomic and molecular phases. In addition,  it would help us to explain the changes in the properties of galaxies at different ages of the Universe,” Neeraj Gupta, an astronomer at IUCAA  and lead investigator of the MALS project, commented.

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