Cosmic Joust: Galaxies Locked in Epic Battle with a Quasar’s Secret Weapon

In the vast expanse of space, a gripping drama is unfolding. Astronomers have observed two galaxies locked in a fierce cosmic battle, hurtling towards each other at a staggering 500 km/s. This galactic clash, dubbed the "cosmic joust," reveals a fascinating – and somewhat unfair – fight where one galaxy wields a secret weapon: a powerful quasar.

The discovery, made using the European Southern Observatory’s Very Large Telescope and the Atacama Large Millimeter/submillimeter Array (ALMA), sheds light on the violent interactions that shaped the early universe. Galaxy mergers and collisions are common, but this particular encounter is unique due to the quasar's influence.

As the galaxies collide, the quasar emits intense radiation, effectively hindering the damaged galaxy’s ability to form new stars. "We call this system the 'cosmic joust'," explains Pasquier Noterdaeme, a researcher at the Institut d'Astrophysique de Paris. Unlike a fair duel, this battle is skewed by the quasar, a supermassive black hole actively gathering material and firing radiation into its opponent's core.

This cosmic event, observed as it occurred 11 billion years ago when the universe was only 18% of its current age, offers a glimpse into a period when both quasars and galaxy mergers were more prevalent. The light from these galaxies took over 11 billion years to reach Earth, allowing astronomers to peek into the universe's past.

Sergei Balashev, a researcher at the Ioffe Institute in St Petersburg, Russia, notes, "Here 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." The radiation disrupts gas and dust clouds, leaving only small, dense regions incapable of forming new stars, thus severely weakening the targeted galaxy.

Adding another layer of complexity, the interaction between the galaxies fuels the quasar itself. The collision brings vast amounts of gas to the supermassive black hole, strengthening it and making it more powerful. Essentially, the galactic battle powers the weapon being used against the other galaxy.

The discovery highlights the profound influence of quasars on galaxy evolution and the dynamic nature of the universe. Future instruments, like the Extremely Large Telescope (ELT), promise even more detailed insights into these ancient galactic conflicts.

What does this unequal cosmic battle tell us about the forces that shape the universe? Share your thoughts and theories in the comments below!

• ALMA
• galaxies
• quasar