For the first time, astronomers have observed a galaxy wielding a quasar like a cosmic weapon—piercing its rival with radiation that disrupts star formation. The galactic battlefield, seen as it was 11 billion years ago, offers stunning insights into the Universe’s most violent past.
Key Points at a Glance
- Two galaxies caught mid-collision 11 billion light-years away
- One galaxy’s quasar irradiates the other, halting star formation
- Observation made with ESO’s VLT and ALMA in Chile
- First direct evidence of a quasar transforming a companion galaxy’s gas
In the vast, dark arena of the early Universe, two galaxies have been caught in a titanic struggle. The scene is not a silent drift but a violent, radiant clash—a cosmic joust. In this high-speed galactic battle, one galaxy has turned its core into a spear: a blazing quasar that fires beams of radiation directly into its rival.
This celestial drama, captured in exquisite detail by the European Southern Observatory’s Very Large Telescope (VLT) and the Atacama Large Millimeter/submillimeter Array (ALMA), offers the first-ever direct evidence that a quasar can fundamentally transform a nearby galaxy. The results, published in Nature, could reshape how we understand galaxy evolution and the deadly influence of supermassive black holes.
The two galaxies, seen as they existed over 11 billion years ago, are colliding at speeds of 500 km/s. One harbors a quasar—a luminous beacon powered by a ravenous black hole. Its radiation slices through its opponent, stripping away vast clouds of gas and leaving only small, dense pockets. These remnants are too compact to birth new stars, effectively shutting down star formation and turning a once-thriving stellar nursery into a galactic ghost town.
“This is the first time we’ve witnessed the effect of a quasar’s radiation directly altering the gas structure inside another galaxy,” says Sergei Balashev, co-lead of the study and researcher at the Ioffe Institute in Russia. His team describes the event as a “cosmic joust,” a nod to its medieval brutality and tactical precision.
Pasquier Noterdaeme, co-lead from the Institut d’Astrophysique de Paris, explains that the recurring collisions between the galaxies also funnel fresh fuel into the quasar-hosting galaxy’s black hole. As the black hole feeds, the quasar grows stronger, continuing its assault in a feedback loop of cosmic violence.
ALMA’s precise imaging made it possible to separate the two galaxies, which previous instruments had blurred into a single object. The VLT’s X-shooter instrument then allowed scientists to analyze the quasar’s light as it passed through the gas in the neighboring galaxy—revealing the telltale signs of molecular devastation.
These findings are more than a spectacular cosmic episode—they offer a vital clue to a longstanding mystery. Why do some galaxies stop forming stars while others flourish? This study suggests quasars may play a pivotal role, not just by disrupting their own hosts, but by targeting other galaxies too.
As technology advances, instruments like ESO’s upcoming Extremely Large Telescope will be able to explore even more such galactic interactions. “It will certainly allow us to push forward a deeper study of this, and other systems,” says Noterdaeme, “to better understand the evolution of quasars and their effect on galaxies.”
The “cosmic joust” might be billions of years old, but it speaks directly to modern astronomy’s deepest questions: How do galaxies live, die, and transform each other in the grand dance of the Universe?
Source: European Southern Observatory
