Astronomers caught a brutal act of cosmic violence for the first timeâ€"one galaxy piercing another with deadly radiation.
In the cold, ancient reaches of the cosmos, two galaxies are duking it out in a battle that’s been raging for billions of years. But it's not a fair fight, a team of astronomers recently found, as one of the galaxies is using a quasar to pierce the other, severely hampering its development.
The team observed the "cosmic joust," as they've dubbed the interaction, using Chile’s Atacama Large Millimeter/submillimeter Array (ALMA) and the European Southern Observatory’s Very Large Telescope. The researchers witnessed something bizarre: one galaxy shooting a beam of radiation directly into another, disrupting its ability to form new stars. The team's results, published today in Nature, offer a front-row seat to some of the most intense intergalactic violence the universe has to offer.
The interaction is so distant that the light in the images took 11 billion years to reach us. The cosmic conflagration appears just as it did when the universe was just 18% of its current age. Though they appear plain and inert in the above image, the galaxies are actually hurtling towards one another at over 311 miles per second (500 kilometers per second).
"We discovered a quasarâ€"likely triggered by the merging of two galaxiesâ€"that is actively transforming the gas structure in its companion galaxy," Pasquier Noterdaeme, a CNRS researcher at the Institut d'Astrophysique de Paris and lead author of the paper, told Gizmodo in an email. "The idea that galaxy mergers give rise to quasars has long been proposed, mainly supported by statistical studies of host galaxy morphologies," Noterdaeme added. "In our case, we caught the two galaxies in the act."
The team found that radiation from one galaxy's quasarâ€"an active galactic core powered by a supermassive black holeâ€"was disrupting regions in the other galaxy. That energy is shooting straight into the other galaxy like a lance, slicing through clouds of gas and dust. Because of the disturbance, the researchers say, the regions are probably too small to form new stars; the quasar-wielding galaxy effectively sabotaged its opponent's ability to birth new light.
“We see for the first time the effect of a quasar’s radiation directly on the internal structure of the gas in an otherwise regular galaxy,†said Sergei Balashev, co-lead author of the study and a researcher at the Ioffe Institute in Russia, in an ESO release.
But the galaxy with the quasar isn’t just chipping away at the otherâ€"it’s also transforming itself. As the galaxies brush past one another, the interaction funnels gas toward the quasar’s central black hole, fueling it for more violent outbursts.
The unique interaction was made visible thanks to ALMA's high resolution, which allowed astronomers to see that the light source in deep space was actually two galaxies (previous observations made the closely spaced objects appear as a single entity). ESO's X-shooter scrutinized the quasar's light, helping the researchers understand how the radiation affected the other galaxy.
There's more to discover beyond the horizonâ€"and I'm not talking about the event horizon. Instruments like the upcoming Extremely Large Telescope (ELT) could let scientists dissect even more of these ancient galactic brawls, giving us a clearer picture of how quasars shape the galaxies they live inâ€"and destroy the ones they don’t.