A team of astronomers has identified the most distant pair of merging quasars ever observed, providing new insights into the early universe.
These quasars, seen as they were around 900 million years after the Big Bang, mark the first confirmed pair from the Cosmic Dawn era. The discovery, published in The Astrophysical Journal Letters, underscores the critical role that galactic mergers played in shaping the cosmos as we know it today.
The Cosmic Dawn and Its Significance
The Cosmic Dawn is a critical period in the universe's history, stretching from approximately 50 million to one billion years after the Big Bang. During this epoch, the first light sources, including stars and galaxies, began to form, illuminating the universe and driving the reionization of neutral hydrogen.
Finding merging quasars from this period is particularly significant because it offers direct evidence of the early interactions that shaped large-scale structures in the universe. "The existence of merging quasars in the Epoch of Reionization has been anticipated for a long time. It has now been confirmed for the first time,” said Yoshiki Matsuoka, an astronomer at Ehime University in Japan.
Observations and Methods
The quasars were identified using the Subaru telescope's Hyper Suprime-Cam and confirmed with follow-up spectroscopic imaging.
The light from these quasars, observed at a redshift of z = 6.05, indicates they are seen as they were over 12 billion years ago. Initial images showed the quasars as faint red blotches among numerous closer galaxies and stars.
Detailed analysis revealed that these blotches were indeed quasars, thanks to the spectroscopic capabilities of the Subaru and Gemini North telescopes. “A few hundreds of quasars are now known in the early universe, but none of them have been found in a pair,” Matsuoka explained. “This is contrary to a naive expectation from the standard theory of cosmology, which suggests that the universe has evolved via frequent mergers of galaxies, which would naturally result in many merging quasar pairs observed throughout the universe.”
Characteristics of the Quasars
At the heart of each quasar is a supermassive black hole, each approximately 100 million times the mass of the Sun. These black holes, by far some of the most massive objects in the early universe, are significant because their masses are about the same, leading researchers to refer to them as twins.
The interaction between the two quasars is further evidenced by a bridge of gas stretching between their host galaxies, indicating a major galactic merger in progress. This interaction is not just a localized phenomenon but a large-scale event affecting the structure and dynamics of the surrounding galaxies. “While it is only the first and single case, the present finding indicates that supermassive black holes and galaxies have indeed evolved through mergers with each other,” Matsuoka added.
Implications for Cosmology
The presence of merging quasars in the Cosmic Dawn aligns with theoretical predictions about the universe's evolution. It suggests that the early universe underwent significant galactic interactions, leading to the formation of large structures observed today. This discovery provides empirical evidence supporting the standard cosmological model of hierarchical structure formation.
The merging of these quasars offers a glimpse into the processes that led to the growth of supermassive black holes and the development of galaxies. "It supports our standard paradigm of how the universe has evolved, under the strong pull of the gravity that affects every single bit of material,” Matsuoka stated. The merging quasars serve as a key piece of the puzzle in understanding the early universe’s dynamics and the role of gravity in shaping cosmic structures.
Upcoming Observations with Advanced Telescopes
The team plans to conduct further observations with the James Webb Space Telescope to study the gas dynamics within these galaxies and their star formation processes. Additionally, upcoming telescopes like the Vera Rubin Observatory will enhance the ability to detect and classify distant astronomical objects, offering more opportunities to explore the early universe.
These future observations will provide deeper insights into how the interactions between supermassive black holes and their host galaxies influenced the broader cosmic environment. The researchers hope to clarify the nature of the gas flows and star formation activities in these merging galaxies, shedding light on the complex processes that drive galaxy evolution.
The identification of this quasar pair is a groundbreaking step in understanding the complexities of the universe's formative years, highlighting the importance of continued astronomical research and advanced observational technologies. As new instruments come online and techniques improve, astronomers will continue to peel back the layers of the cosmos, uncovering the secrets of its earliest epochs and the monumental events that have shaped its history.