Astronomers have observed a high-speed galactic collision 11 billion light-years away, a system they've aptly named the "cosmic joust." This rare event provides a direct glimpse into the early universe and how supermassive black holes influence galaxy evolution.
Key details of the "cosmic joust":
- Location and Time: The collision is happening 11 billion light-years away, meaning the light we are seeing now left the galaxies when the universe was only about 18% of its current age.
- Participants: Two galaxies are involved. One hosts a quasar, a supermassive black hole that is actively consuming surrounding material and emitting intense radiation. The other galaxy is being directly impacted by this radiation.
- High-Speed Encounter: The companion galaxy is hurtling towards the quasar-hosting galaxy at approximately 1.2 million miles per hour (2 million kilometers per hour).
- Observatories: Scientists used the Atacama Large Millimeter/submillimeter Array (ALMA) to distinguish the two galaxies and observe their molecular gas content. The X-shooter instrument on the Very Large Telescope (VLT) was used to analyze the quasar's light as it passed through the companion galaxy. Both observatories are located in Chile.
- The "Joust" Effect: The quasar's intense radiation is blasting apart the gas within the companion galaxy, leaving behind compact cloudlets that are too small to form new stars. This directly observed phenomenon, where a quasar's radiation affects the internal structure of gas in another galaxy, had previously only been theorized.
- Fueling the Quasar: The gravitational forces of the collision are also pulling more gas towards the supermassive black hole, further fueling the quasar and intensifying its radiation.
- Significance: This discovery offers unique insights into the early universe, when galaxy mergers and quasar activity were far more common. It helps astronomers understand how quasars can "sculpt" their surroundings and influence the evolution of galaxies by suppressing star formation. Scientists believe such mergers play a crucial role in the growth and evolution of galaxies and their central supermassive black holes.
This "cosmic joust" is a dramatic example of the powerful interactions that shaped the universe's early history, providing a valuable opportunity to study phenomena that were once only in the realm of theoretical astrophysics.