Galaxies in the great voids of the universe grow more slowly than the rest

Cosmic voids are calm environments of slow evolution that can shed light on the initial conditions of the universe. Now, a study in which the Instituto de Astrofísica de Andalucía participates shows, for the first time in an observational way, that galaxies that inhabit sparse regions of the universe evolve more slowly than those in highly populated areas.

Galaxies are the fundamental building blocks of the large-scale structure of the universe, and they draw a sponge-like network that shows dense clusters, filaments, sheet walls and very sparse regions, known as cosmic voids. These voids constitute the least dense regions of the universe, since they occupy around 80% of its volume and contain only 10% of its mass. An international team has published in Nature a work that shows that the galaxies that inhabit these voids evolve more slowly than the rest.

With this purpose, the CAVITY project was born, headed 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 has succeeded in estimating, for the first time, the rate at which galaxies in cosmic voids form stars throughout their history, as well as the role that the large-scale structure of the universe plays in the evolution of stars. 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 some ten thousand galaxies located in voids, filaments, walls, and clusters.

The scientific team has been able to estimate the ages and masses of the stars that make up these galaxies and describe their star formation history, which has revealed that galaxies in voids evolve more slowly than galaxies with denser structures.

Además, han hallado que las primeras galaxias que se formaron en el universo evolucionaron a la misma velocidad independientemente de la estructura en la que se encuentren ahora.

However, about eleven billion years ago, when the universe was 2.8 billion years old, the evolutionary histories of the galaxies began to diverge, indicating that in the early stages of the universe, large-scale structure might not have existed. state so defined as to generate differences in the evolution of the galaxies that formed then, but in later stages.

This large-scale structure is the result of the evolution of the universe from the Big Bang, and the study of the current distribution of galaxies and their properties allows us to rewind time and obtain information about the initial conditions of the universe.

The high density of filaments and clusters accelerates and alters the characteristics of galaxies, but voids are calm 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 the galaxies, an area of ​​great relevance although small in size. We are collecting data in Calar Alto with a spatial resolution that will allow us to explore both the global and local properties of the galaxies that reside in these cosmic voids”, says Rubén García-Benito, a researcher at the IAA-CSIC who is participating in the work and in the CAVITY project.