Ultraluminous infrared galaxies are the rarest and most extreme star-forming systems and are found only in the distant universe.
Radiative distribution of stars, cold gas, and ionized gas in the unusual HyLIRG Einstein ring PJ0116-24. Image courtesy of Liu others., doi:10.1038/s41550-024-02296-7.
“Ultraluminous Infrared Galaxies (HyLIRGs) are incredibly luminous galaxies illuminated by extremely rapid star formation within their interiors,” said Dr Daizhong Liu from the Max Planck Institute for Extraterrestrial Physics and his colleagues.
“Previous studies had suggested that such extreme galaxies must have arisen through galactic mergers.”
“The collisions of these galaxies are thought to create regions of dense gas that trigger rapid star formation.”
“However, isolated galaxies could also become HyLIRGs through internal processes alone if star-forming gas flows rapidly toward the galaxy's center.”
In the new study, the astronomers focused on a gravitationally lensed HyLIRG galaxy known as PJ0116-24.
“PJ0116-24 is so distant that it took its light about 10 billion years to reach Earth,” the researchers said.
“By chance, the foreground galaxy acts as a gravitational lens, bending and magnifying the light from the background galaxy, PJ0116-24, and directing it towards the Einstein ring.”
“This precise configuration of space allows us to magnify very distant objects and see them with a level of detail that is very difficult to achieve any other way.
The researchers used ESO's Very Large Telescope (VLT) and the Atacama Large Millimeter/submillimeter Array (ALMA) to study the motion of gas within PJ0116-24.
“ALMA tracks the cold gas which appears blue here, while the VLT with its new High Resolution Imaging Spectrograph (ERIS) tracks the warm gas which appears red,” the researchers say.
“Thanks to these detailed observations, we now know that the gas in this extreme galaxy rotates in an organized manner, rather than the chaotic state expected after a galaxy collision. A stunning result!”
“This convincingly shows that a merger is not necessarily required for a galaxy to become a HyLIRG.”
Team paper Published in the journal Natural Astronomy.
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D. Liu othersA detailed study of a rare, ultra-luminous rotating disk in a 10 billion year old Einstein ring. Nat AstronPublished online July 15, 2024; doi: 10.1038/s41550-024-02296-7
Source: www.sci.news
