Australian astronomers have discovered a massive hydrogen gas bridge that connects two dwarf galaxies, providing new information about the interactions and evolution of galaxies.
The International Center for Radio Astronomy Research (ICRAR) said in a statement on Wednesday that researchers from the University of Western Australia (UWA) node had discovered a massive structure that extends an incredible 185,000 light-years between galaxies NGC 4532 and DDO 137, which are 53 million light-years from Earth.
Additionally, the study, which was published in the Royal Astronomical Society’s Monthly Notices, showed that the bridge was accompanied by the longest known tail of gas, which stretched 1.6 million light-years.
Professor Lister Staveley-Smith, an astronomer at ICRAR UWA and the study’s lead author, said the discovery represented a major advancement in our knowledge of how galaxies interact.
The observed gas dynamics were largely influenced by the tidal forces between these galaxies as well as their closeness to the massive Virgo cluster of galaxies, according to Staveley-Smith.
“As the galaxies rotated around each other and moved toward the hot gas cloud surrounding the Virgo cluster, which was 200 times hotter than the Sun’s surface, they experienced what is known as ram pressure, which stripped and heated the gas from the galaxies,” he said, adding that the process lasted a billion years and looked like a satellite burning up on re-entry.
Staveley-Smith said, “The density of electrons and the speed at which galaxies are falling into the hot gas cloud are enough to explain why so much gas has been pulled away from the galaxies and into the bridge and surrounding areas.”
The observations were made as part of the Widefield ASKAP L-band Legacy All-sky Blind surveY, also known as WALLABY, which maps the sky and investigates how hydrogen gas is distributed throughout galaxies.
Study co-author and ICRAR UWA astrophysicist Professor Kenji Bekki said, “Neutral hydrogen plays a crucial role in the formation of stars, making this finding fundamental to understanding how galaxies interact and evolve, particularly in dense environments.”
