In the cold, ancient vastness of space, two galaxies are squaring off in a battle that has been going on for billions of years. But it’s not a fair fight, as a team of astronomers recently discovered, as one of the galaxies is using a quasar to pierce the other, severely hindering its evolution.
The team observed the “cosmic duel,” as they 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 strange: one galaxy fired a beam of radiation directly at another, disrupting its ability to form new stars. The results of the study, published today in the journal Nature, provide 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 fire looks the same as it did when the universe was only 18% of its current age. Although the galaxies look flat and inert in the image above, they are actually hurtling toward each other at speeds of over 311 miles per second (500 kilometers per second).
“We have discovered a quasar – probably caused by the merger of two galaxies – that is actively transforming the structure of the gas in the companion galaxy,” Pasquier Noterdaeme, a CNRS researcher at the Paris Astrophysical Institute and one of the paper’s lead authors, told Gizmodo in an email. “The idea that galaxy mergers lead to the emergence of quasars has been proposed for a long time, mainly based on statistical studies of the morphology of the host galaxies,” Noterdaeme added. “In our case, we caught two galaxies in the act.”
The team found that radiation from one galaxy’s quasar – an active galactic nucleus powered by a supermassive black hole – was destroying regions in the other galaxy. This energy shoots straight into the other galaxy like a spear, slicing through clouds of gas and dust. The researchers say that because of the perturbation, these regions are likely too small to form new stars; the quasar-hosting galaxy has effectively sabotaged its opponent’s ability to give birth to new light.
“For the first time, we see the effect of quasar radiation directly on the internal structure of gas in an ordinary galaxy,” said Sergey Balashev, co-author of the study and a researcher at the Ioffe Institute in Russia, in an ESO release.
“But a galaxy with a quasar doesn’t just destroy another – it also transforms itself. As the galaxies rush past each other, the interaction sends gas toward the quasar’s central black hole, fueling it for more powerful outbursts.
The unique interaction was made visible by ALMA’s high resolution, which allowed astronomers to see that the light source in deep space was actually two galaxies (previous observations had made the closely spaced objects appear as one). ESO’s X-ray spacecraft carefully studied the quasar’s light, helping researchers understand how the radiation affected the other galaxy.
There is even more to discover beyond the horizon – and I’m not talking about the event horizon. Instruments like the upcoming Extremely Large Telescope (ELT) could allow scientists to dissect even more of these ancient galactic clashes, giving us a clearer picture of how quasars shape the galaxies they live in and destroy the ones they don’t.
