Analysis from the ESO’s Very Large Telescope (VLT) and ALMA data indicates that intense radiation from a quasar within these galaxies affects the gas properties of other galaxies, reducing their ability to form new stars.
Artistic impression of a galaxy merger where the right galaxy hosts a quasar at its core. This quasar, containing a supermassive black hole, emits a powerful radiation cone that affects neighboring galaxies. This interaction can destroy gas and dust clouds, leaving behind only denser regions that may struggle to form stars. Image credit: ESO/M. Kornmesser.
“In the far reaches of the universe, two galaxies are entangled in an exhilarating conflict,” remarked Dr. Paschier Notardem, an astronomer affiliated with the Paris Astronomical Institute.
“On a collision course at speeds of 500 km/s, they collide multiple times, only to push one another away before gearing up for another round.”
“Thus, we refer to this system as the ‘space joust.’ However, these galactic contenders don’t fight fairly, utilizing quasars to strike with beams of radiation.”
Quasars are the luminous cores of certain distant galaxies powered by supermassive black holes, emitting substantial amounts of radiation.
The combination of a quasar with a galaxy was significantly more common during the universe’s first billion years, allowing astronomers to glimpse the remote past using powerful telescopes.
The light from this “joust of the universe” traveled over 11 billion years to reach us, providing a snapshot of the universe when it was merely 18% of its current age.
ALMA image showcasing the molecular gas content of two galaxies involved in a collision. Image credits: ALMA/ESO/NAOJ/NRAO/Balashev et al.
“According to Dr. Sergei Balashev from the Ioffe Institute,
the observations from the new VLT/ALMA indicate that radiation from the quasar J012555.11-012925.00 obliterates the normal gas and dust clouds in the surrounding galaxy, leaving only the densest regions.
These regions are likely too limited for star formation, causing a significant decline in stellar nurseries within the affected galaxy.
However, the transformed galaxies are not the only ones undergoing changes.
“These mergers are believed to funnel substantial amounts of gas into the supermassive black holes at the galaxies’ centers,” Dr. Balashev mentioned.
“In this cosmic arena, fresh supplies of fuel come within reach of black holes that power the quasar.”
“As these black holes are nourished, the quasar can persist in its destructive assault.”
A paper detailing these findings was published today in the journal Nature.
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S. Balashev et al. Quasar radiation transforms gas in a merged companion galaxy. Nature Published online on May 21, 2025. doi:10.1038/s41586-025-08966-4
Source: www.sci.news
