Galaxies in the big voids of the universe grow slower than the rest

Galaxies are the fundamental building blocks of the large-scale structure of the universe and draw a sponge-like network that shows dense clumps, filaments, sheet walls and very sparse regions known as cosmic voids.

These voids constitute the least dense regions of the universe, as they occupy about 80% of its volume and contain only 10% of its mass. An international team published in Nature The work which shows that the galaxies that inhabit these voids evolve more slowly than the others.

Previous studies have shown that empty galaxies exhibit, on average, properties that correspond to younger, less evolved systems than galaxy filaments, walls and clusters. However, it has never been observed observationally that there evolutionary differences each other.

With this purpose, the CAVITY project was born, led by the University of Granada, developed from the Calar Alto Observatory and in which the Institute of Astrophysics of Andalusia (IAA-CSIC) participates.

The CAVITY team was able to estimate, for the first time, the speed in which galaxies in cosmic voids form stars over their history, as well as the role that the large-scale structure of the universe plays in the evolution of galaxies.

This is the first statistically significant study on the evolution of galaxies in the different large-scale structures of the universe, with data from about ten thousand galaxies located in voids, filaments, walls and clusters.

Simulation of the large-scale structure of the universe, showing dense clusters of galaxies, filaments, shell walls and voids. / Project Uchuu.

The scientific team was able to estimate the ages and masses of the stars that make up these galaxies and describe their star formation historywhich revealed that galaxies in the void evolve more slowly than galaxies with denser structures.

Furthermore, they found that the first galaxies that formed in the universe evolved at the same speed, regardless of the structure where are they now.

Initial conditions of the universe

However, around eleven billion years ago, when the universe was 2.8 billion years old, the evolutionary histories of galaxies began to unravel. divergewhich indicates that in the early stages of the universe the large-scale structure may not have been defined in such a way as to generate differences in the evolution of the galaxies that formed then, but it was in later stages.

This large-scale structure is the result of the evolution of the universe since the big Bangand the study of the current distribution of galaxies and their properties allows us to go back in time and obtain information about the initial conditions of the universe.

The high density of filaments and clusters accelerate and change the characteristics of galaxies, but voids are silent environments of slow evolution that can shed light on the initial conditions of the universe.

“These results are based on the analysis of the integrated spectra of the central zone of galaxies, an area of ​​great relevance although small in size. We are collecting data at Calar Alto at a spatial resolution that will allow us to explore the global and local properties of galaxies that reside in these cosmic voids.” Ruben Garcia-BenitoIAA-CSIC researcher who participates in the work and in the CAVITY project.