Photo: ESO/M. Kornmesser

Science and technology

In a groundbreaking study from the University of Turku, new insights have emerged about the formation of quasars, challenging longstanding theories. Previously, it was believed that quasars, which are incredibly bright galaxies powered by supermassive black holes consuming cosmic gas and dust, formed primarily through galaxy collisions. However, this latest research shows that quasars can also form independently of such violent interactions.

For decades, the dominant theory posited that the supermassive black holes at the centers of quasars were the result of massive galaxy mergers. Recent observations of quasars and their neighboring galaxies, located a few billion light-years from Earth, have painted a different picture. These findings contradict previous numerical simulations that predicted quasar activation through galaxy mergers.

Maria Stone, the doctoral researcher behind this study, explains, “While cosmic simulations have shown that quasar activation through galaxy mergers is theoretically possible, it is crucial to validate these models with real observations.”

The new research demonstrates that active supermassive black holes can ignite within their host galaxies without external triggers like mergers. These processes occur due to internal dynamics within the galaxies themselves. Stone's observations reveal that galaxies near quasars exhibit star formation and characteristics similar to those near inactive galaxies. This suggests that a galaxy's environment plays a less significant role in quasar activation than previously thought.

Stone conducted her observations using advanced telescopes, such as the Nordic Optical Telescope (NOT) in the Canary Islands and the New Technology Telescope (NTT) in Chile. By employing spectroscopy, she analyzed the light from stars in galaxies neighboring quasars. This technique involves dispersing light into a spectrum, much like a prism creates a rainbow, allowing researchers to gather detailed information about the galaxies' properties, including their distance, shape, age, star formation rate, and chemical composition.

These findings are prompting a reevaluation of how supermassive black holes and quasars influence their surrounding galaxies. Stone notes that some newer simulations suggest internal processes, such as the instability of spiral arms, could drive gas toward the galaxy center, igniting a quasar without any external interaction.

“While the idea of quasars forming through galaxy mergers was exciting, we now see that it’s not the full story. We need to adjust our understanding, similar to how we once thought planets revolved around the Earth,” Stone reflects. “The true picture of how the universe operates might be different from what we’ve imagined, but it’s even more thrilling.”

Stone’s research opens new avenues for understanding the role of quasars in cosmic evolution and the mechanisms behind supermassive black hole activation. By continuing to refine our models and validate them with observational data, scientists hope to uncover a more comprehensive understanding of these fascinating cosmic phenomena.

The study challenges established beliefs about quasar formation and highlights the importance of continuous observation and theoretical adjustment in astrophysics. With these new insights, researchers are one step closer to unraveling the complex dynamics that govern our universe.