Two Remote Galaxies Engaged in a Turbulent Cosmic Clash

Two galaxies situated at an astonishing 11 billion light-years from our planet seem to be colliding repeatedly at velocities surpassing 1 million miles per hour. This remarkable occurrence has given astronomers a rare opportunity to witness an intense galactic merger, in which one galaxy is essentially piercing through the other with intense radiation from a formidable quasar — a phenomenon researchers have termed the “cosmic joust.”

A quasar, abbreviated from “quasi-stellar object,” is an extremely bright area at the center of a galaxy, outshining all of the galaxy’s stars collectively. Driven by a supermassive black hole that consumes nearby material, quasars emit light beams so brilliant they may appear as individual stars through telescopes. Scientists have long postulated that galactic collisions can ignite quasars, but concrete evidence has been hard to come by — until now.

“This system exemplifies what we call the ‘cosmic joust,’” remarked Pasquier Noterdaeme, an astronomer at the Institut d’Astrophysique de Paris and a co-author of the study.

The recent findings, published in the journal Nature, not only validate the notion that galactic mergers can activate quasars, but also uncover the devastating impact of these cosmic forces. The radiation emitted by the quasar seems to have sterilized its galactic rival, impeding its capacity to form new stars by disturbing the gas clouds typically responsible for star formation.

A Peek Into the Ancient Past

Though the collision seems to be occurring in the present, it actually took place billions of years ago — when the universe was merely 18% of its present age. Since light from such distant objects requires billions of years to reach Earth, astronomers are essentially observing events from the past.

To investigate the occurrence, an international group of researchers utilized two powerful observatories in the Chilean desert: the Atacama Large Millimeter/submillimeter Array (ALMA) and the European Southern Observatory’s Very Large Telescope. Their results uphold a longstanding theory that galaxy mergers can nourish supermassive black holes and initiate quasar activity, which can significantly alter the galaxies involved.

“For the first time, we are witnessing the direct influence of a quasar’s radiation on the inner structure of gas within a galaxy,” stated Sergei Balashev, a co-author from the Ioffe Institute in Russia.

Star Formation Halted

In the galaxy affected, the gas that would typically come together to form stars has been transformed by the quasar’s energy. Rather than creating large, diffuse clouds, the gas has been compacted into small, dense masses — effectively stifling the formation of new stars. This indicates the quasar’s radiation has sterilized certain areas of the galaxy, freezing its development.

This finding enhances our comprehension of how supermassive black holes — which are believed to exist at the centers of nearly all galaxies — can affect their environment. While black holes are recognized for their gravitational influence, they can also expel matter in powerful jets, a phenomenon scientists are still endeavoring to fully understand.

Feeding the Flame

Interestingly, the galactic conflict not only affected the victim galaxy. It also directed fresh gas into the galaxy hosting the quasar, nourishing the supermassive black hole at its core and sustaining the quasar’s activity. This feedback loop — where galaxy mergers supply black holes with gas, which in turn releases energy that reshapes galaxies — is a crucial mechanism in cosmic evolution.

“These mergers are believed to funnel significant amounts of gas to supermassive black holes located in galaxy centers,” Balashev clarified.

Quasars as Ancient Timepieces

Quasars are remnants from the early universe. The closest ones to Earth still lie hundreds of millions of light-years away, meaning we observe them as they existed hundreds of millions of years in the past. Their rarity in the nearby universe implies they were more prevalent during the cosmos’s youth.

Since the first quasar was identified in 1963 by astronomer Maarten Schmidt, scientists have been captivated by their power and enigma. Investigating quasars not only aids in understanding black holes and galaxy formation, but also provides insights into the history and evolution of the universe.

As astronomers continue to delve deeper into space, events such as the “cosmic joust” furnish invaluable knowledge regarding the violent, dynamic events that shape galaxies — and the universe as a whole.