Astronomers used the ALMA radio telescope to observe a rare galaxy merger 12.8 billion years ago. This early cosmic event involved a pair of galaxies whose interaction was expected to create a monster galaxy characterized by intense quasar activity and bursts of star formation. These findings are crucial to understanding the stages of formation of galaxies and black holes in the universe.

Dancing galaxies create magical cosmic dawn An artist's impression of the interacting galaxies observed in this study. Gravitational interactions during mergers trigger stellar explosions and quasar activity. Source: ALMA (ESO/NAOJ/NRAO), T. Izumietal.

The characteristics of these galaxies suggest that the merger will create a monster galaxy that is one of the brightest types of objects in the universe. These results are important for understanding the early evolution of galaxies and black holes in the early universe.

Quasars are bright objects in the early universe driven by material falling into supermassive black holes at the centers of galaxies. The most widely accepted theory is that when two gas-rich galaxies merge into a larger galaxy, the gravitational interaction of the two galaxies causes gas to fall toward a supermassive black hole in one or both of the galaxies, causing quasar activity.

To test this theory, an international research team led by Takuma Izumi used the ALMA (Atacama Large Millimeter/submillimeter Array) radio telescope to study the earliest known pair of close quasars. The pair of quasars was discovered in images taken by the Subaru Telescope by Yoshiki Matsuoka of Ehime University in Japan.

This pair of quasars is located in the direction of the constellation Virgo and existed during the first 900 million years of the universe. This pair of quasars is very faint, indicating that they are still in the early stages of evolution. ALMA's observations mapped the quasar's host galaxy and showed that the two galaxies are connected by a "bridge" of gas and dust. This suggests that the two galaxies are actually merging.

Through the ALMA observations, the team also measured the amount of gas required for the formation of new stars. The team found that the two galaxies are very gas-rich, suggesting that in addition to more quasar activity in the future, the merger will trigger a rapid increase in star formation, a so-called "starburst." The combination of starburst activity and active quasar activity is expected to form an ultra-bright object in the early universe, known as a "monster galaxy."

Compiled from /scitechdaily