An international team of astronomers, as part of the Widefield Askap L-Band Legacy All-Sky Survey (Wallaby), observed DDO 137 (Wallaby J123424+062511). Their findings uncovered a vast bridge of neutral hydrogen, measuring 185,000 light-years, connecting the two galaxies, along with various arms and clouds that link to a longer gas tail (1.6 million light-years) previously identified by the Arecibo telescope.
Radio (left) and light (right) images of NGC 4532/DDO 137. Image credits: ICRAR/D. Lang, Perimeter Institute.
“This discovery marks a significant advance in our understanding of galaxy interactions,” stated Professor Lister Starley Smith from the University of Western Australia Node at the International Centre for Radio Astronomy Research (ICRAR).
“Our simulations indicate that the tidal forces between these galaxies play a crucial role in the observed gas dynamics in close vicinity to the massive Virgo clusters of galaxies.”
“As the galaxies approached the hot gas clouds surrounding the Virgo clusters—temperatures 200 times that of the sun—we experienced what is termed RAM pressure, resulting in gas being stripped away from the galaxy.”
“This phenomenon is analogous to atmospheric burn-up when a satellite reenters Earth’s upper atmosphere, albeit extended over a billion years.”
“The electron density and the velocity at which galaxies descend into these hot gas clouds sufficiently clarify why they were drawn from the galaxy toward the bridge and surrounding regions.”
This observation formed part of the Wallaby Survey, a comprehensive project aimed at mapping the sky and examining the hydrogen gas distribution across galaxies using CSIRO’s Askap Radio telescope.
“Neutral hydrogen is vital for star formation, making this discovery pivotal in understanding how galaxies interact and evolve, particularly in densely packed environments,” remarked Professor Kenji Bekki of ICRAR.
“This system exhibits striking similarities to our Milky Way and Magellanic Clouds, offering a unique opportunity for a detailed examination of such interactions,” noted Professor Stavely-Smith.
“Grasping the dynamics of these gas bridges is crucial for understanding galaxy evolution over time, the redistribution of galactic gases, and the various conditions impacting star formation within galaxies.”
“This enhances our overall understanding of the universe’s largest structures and their lifecycle.
result will be published in Monthly Notices from the Royal Astronomical Society.
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L. Stavely-Smith et al. 2025. WallabyPilot Survey: Extensive interaction between NGC 4532 and DDO 137 and Virgo clusters. mnras 543(1): 526-539; doi: 10.1093/mnras/staf1443
Source: www.sci.news
