New cosmic simulation reveals how galactic central components form and evolve

A recent simulation of a galaxy analogous to the Milky Way demonstrated how two elements located in the central areas of various galaxies can develop and evolve in an interconnected manner. This study was conducted by the SMUGGLE-Ring project and focused on the correlation between stellar nuclear disks and nuclear star clusters.

Researchers from the Leibniz Institute for Astrophysics Potsdam conducted this work, which was published as a letter to the editor in the journal Astronomy & Astrophysics in 2026. For this, they employed a high-resolution hydrodynamic simulation, tracking the evolution of a barred spiral galaxy similar to the Milky Way over four billion years.

The scientists discovered that the stellar bar structure functions as a system that transports gas to the central region, providing essential material for the birth of new stars. Furthermore, the model suggested that dark matter dynamics have an impact on the evolution of these structures, potentially modifying the trajectory of galactic nuclei.

For many years, astronomers studied nuclear star clusters and stellar nuclear disks separately, assuming they might have been created by distinct processes. Previous observations did not establish a clear link between their sizes and masses, leaving the question of their common origin open.

The new simulation changed this view by successfully replicating, within a single physical model, the emergence of these two central components. The result indicates that both can grow from the same supply of gas transported to the core by the galaxy's stellar bar.

According to the research, the accumulation of gas in the center triggers new periods of star formation. These cycles are affected by the energy return generated by stars reaching the end of their lives, releasing energy and creating shock waves that stimulate new stellar creations.

Over billions of years, this process resulted in the accumulation of hundreds of millions of solar masses in stars within the simulated central structures. The researchers emphasize that the great advantage of this model is enabling the visualization of phases that cannot be directly monitored in real galaxies, which are usually examined only at a specific moment of their existence.

The simulation also helped clarify why previous studies could not find an obvious connection between nuclear star clusters and stellar nuclear disks. The lack of a direct correlation does not necessarily imply that these systems have different origins.

The study suggests that the perceived differences may stem from the fact that both structures modify their proportions over time. During long periods of growth, their masses and sizes can gradually diverge, causing galaxies at different stages to appear to have cores formed by distinct mechanisms.

The research also adopted a more realistic representation of dark matter. Instead of treating it as a static background, the model included particles capable of following its dynamics, allowing the galactic bar to evolve naturally.

This treatment also revealed the existence of a region with lower dark matter density around the bar, a phenomenon called a 'dark void'. The study associates this characteristic with the interaction between stars and dark matter, driven by the bar's rotation.

Another important finding of the simulation was the arrival of an extremely massive star cluster at the center of the modeled galaxy. This cluster, with approximately thirty million solar masses, migrated towards the nucleus and merged with the existing nuclear star cluster.

This scenario is relevant because recent observations identified large clusters within the bar of the galaxy NGC 1365, some of which are considered potential candidates to migrate to the central region. According to the study, events of this nature can rapidly alter the mass and size of nuclear clusters.

The investigation concludes that such mergers make the evolution of galactic centers even more complex. Since there is a supermassive black hole within the nuclear star cluster of many galaxies, the changes caused by these events can leave marks on the mass of this object, expanding the understanding of the link between various galactic components.