SYDNEY, Sept. 24 (Xinhua) — Astronomers in Australia have found a colossal hydrogen gas bridge linking two dwarf galaxies, offering new insight into how galaxies interact and evolve.
Researchers from the University of Western Australia (UWA) node at the International Center for Radio Astronomy Research (ICRAR) uncovered an immense structure, which spans an astonishing 185,000 light-years between galaxies NGC 4532 and DDO 137, located 53 million light-years from Earth, an ICRAR statement said Wednesday.
The study, published in the Monthly Notices of the Royal Astronomical Society, also revealed that a vast tail of gas accompanied the bridge, extending 1.6 million light-years, making it the longest-ever observed.
The discovery marked a significant step forward in understanding how galaxies interact, said study lead author, ICRAR UWA astronomer Professor Lister Staveley-Smith.
The tidal forces acting between these galaxies, alongside their proximity to the massive Virgo cluster of galaxies, played a crucial role in the gas dynamics observed, Staveley-Smith said.
“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 the process resembled a satellite burning up on re-entry but spanned a billion years.
“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,” Staveley-Smith said.
The observations were part of the Widefield ASKAP L-band Legacy All-sky Blind surveY (or WALLABY), which maps the sky and studies the distribution of hydrogen gas in galaxies.
“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,” said study co-author and ICRAR UWA astrophysicist Professor Kenji Bekki. ■