Astronomers have witnessed something extraordinary. Using some of the world’s most powerful telescopes, they looked 11 billion years into the past. There, they saw two galaxies locked in a violent interaction. One hosted a quasar, a powerful beacon of energy. The other was pierced by the quasar’s radiation. It looked like a galactic duel. Scientists called it a “cosmic joust.” This observation is more than just visually stunning. It tells a new story about how galaxies interacted in the early universe. It shows how quasars shape the evolution of galaxies. And it helps us understand how the cosmos evolved over time.
What is a quasar?
A quasar is an extremely luminous object. It forms when a supermassive black hole devours matter. As this material falls inward, it heats up. The result is a bright, energetic core that outshines entire galaxies. Quasars can shine a thousand times brighter than the Milky Way. They are visible across billions of light-years. Quasars are most common in the early universe. Back then, galaxies were younger and full of gas. That gas often fed the central black holes, triggering these violent outbursts of energy. Today, quasars are rare.
The discovery
The European Southern Observatory (ESO) led this new observation. The team used the Very Large Telescope (VLT) in Chile and data from the Atacama Large Millimeter/submillimeter Array (ALMA). Their target was a pair of interacting galaxies. These galaxies existed when the universe was just 1.2 billion years old. The system lies in the direction of the constellation Sextans. It is officially known as SDSS J165202.64+172852.3. One galaxy in the pair hosted a bright quasar. The other was its neighbor, separated by about 26,000 light-years. That’s about the same distance from Earth to the center of the Milky Way.
The discovery would not be possible without cutting-edge instruments. The team used MUSE, a spectrograph on ESO’s Very Large Telescope. MUSE collects spectra across a wide field of view. This allows astronomers to study gas movement, composition, and excitation. The Atacama Large Millimeter/submillimeter Array (ALMA) helped as well. ALMA is perfect for detecting cold gas and dust. It allowed the team to measure the gas content and temperature in both galaxies. This combination of tools gave them a complete picture.
The cosmic lance
The team found something remarkable. The quasar’s radiation was not spreading out in all directions. Instead, it formed a narrow, focused beam. That beam shot straight into the neighboring galaxy. It passed through its gas and heated it. It was as if the quasar had thrown a cosmic lance. That lance punctured the companion galaxy, exciting its gas and altering its structure. The effect was so striking that astronomers described it as a jousting match. Hence the name: “cosmic joust.”
This is the first time astronomers have seen a quasar beam directly hitting another galaxy. Before this, scientists knew quasars could affect their surroundings. But it was unclear how far that influence could reach. This observation proves that a quasar can impact a galaxy tens of thousands of light-years away. The quasar’s radiation excited the hydrogen gas in the companion galaxy. This caused it to emit light at specific wavelengths, which astronomers could detect. The beam even compressed some of the gas, potentially triggering new star formation.
Galaxy mergers and star formation
When galaxies interact, their gas clouds collide and compress. This often leads to bursts of star formation. The cosmic lance from the quasar may have enhanced this effect. By compressing the gas in the companion galaxy, the beam may have triggered new star formation. Alternatively, the radiation might heat the gas too much. This could stop it from forming stars. The exact effect depends on many factors, like the beam’s intensity, duration, and angle of impact. In this case, the team observed both effects. Some gas lit up, suggesting new stars may form. But other parts showed signs of heating and disruption.
This observation adds a new piece to the puzzle of galaxy evolution. It shows that a single quasar can impact not just its own galaxy, but a neighbor as well. This has major consequences for how galaxies grow and evolve. It also supports the idea that feedback from quasars can regulate star formation. If the radiation triggers stars in some places and halts it in others, it could control how galaxies change over time.
The cosmic joust is more than a stunning image. It’s a window into the universe’s wild past. It shows that quasars are not just luminous beacons, but also powerful agents of change. They shape galaxies, trigger star formation, and alter cosmic structures. This observation is a milestone. It combines high-resolution instruments, powerful telescopes, and deep analysis. It proves that we are just beginning to understand the full power of quasars.
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