Academics of the CAVITY project from Granada and Lyon 1 publish a study on the galaxies’ evolution in the Nature scientific journal

The CAVITY project team, led by researchers from the University of Granada (UGR) and with the participation of academics from the Université Claude Bernard Lyon 1 (Lyon 1), publishes the study “Galaxies in voids assemble their stars slowly” in Nature scientific journal.

Galaxies are mass concentrations in which the gas from the universe condenses under the action of gravity forming thousands of millions of stars. As the bricks of a house, the galaxies are the fundamental building blocks that conform to the large-scale structure of the Universe. These galaxies are distributed in a sponge-like web characterised by the different large-scale structure environments: dense clusters, elongated filaments, sheet-like walls and low-density regions called ‘cosmic voids’.

The CAVITY project is born with the objective of exploring the properties of galaxies in cosmic voids, aiming to determine whether there are significant differences in the properties of these galaxies as compared to those living in denser environments. The project, led by researchers at the University of Granada, comprises a collaboration of more than 40 researchers from international institutions and has as a key part of the Legacy observations of cosmic void galaxies using the PMAS-PPAK spectrograph located at the Calar Alto Observatory in the Filabres range in Almeria, Spain.

A UGR PhD student, Jesús Domínguez-Gómez, from the CAVITY collaboration, under the supervision of Isabel Pérez and Ute Lisenfeld, and in close collaboration with Tomás Ruiz-Lara from the University of Granada, and with the full support and help of the CAVITY team have managed to estimate, for the first time, the speed at which galaxies in cosmic voids create their stars, and to estimate the role of the environment in their evolution.

Hélène Courtois, from the Institut de Physique des 2 Infinis of the Université Claude Bernard Lyon 1, has also participated in this research collaboration.

The research team has carried out a statistically significant study on the evolution of galaxies living in the different large-scale structures of the Universe analysing the central spectra from the Sloan Digital Sky Survey (SDSS) of 10000 galaxies living in voids, filaments and walls, and clusters. It has been shown that galaxies in cosmic voids evolve slower than those in denser environments. Furthermore, they found that the first galaxies evolved very similarly independent of their large-scale environment until 11 thousand million years ago. From that time, the evolution of the galaxies is marked by their location within the large-scale structure.

The low-density regions of the Universe offer quieter environments in which galaxies can slowly evolve, making these regions excellent probes for the conditions of the early Universe. Ultimately, this study highlights the importance of studying galaxies in cosmic voids and ensures the future success of this ambitious international project led by the University of Granada and the Calar Alto Observatory.

In a short interview with the Communications team of the Arqus Alliance, Jesús Domínguez-Gómez, principal researcher of the article, details concrete aspects of the collaboration of the Arqus universities for the production of this study, as well as the future joint projects they are working on.

How did this collaboration come about, was it through Arqus or did it already exist? How has the Alliance contributed to this achievement?

The collaboration starts with the CAVITY (Calar Alto Integral-field Treasury surveY) project, which studies the galaxies located in the cosmic voids and compares them with galaxies in denser environments to determine how the large-scale structures of the Universe affect the properties of the galaxies. CAVITY is led by researchers from the University of Granada as a long-term observation proposal submitted to the Calar Alto observatory in Almeria, Spain. The collaboration with Hélèn Curtois from the University of Lyon 1, together with the rest of the collaborators from other institutions, is due to her expertise in cosmology and cosmography, which is complementary to the experience in extragalactic physics of the members of the University of Granada. The Arqus Alliance has contributed by paying the printing expenses for the publication of the paper version of the article that is presented here.

According to your opinion, how is the Arqus Alliance contributing to increasing the quality scientific production of the research groups of its university members?

The Arqus alliance benefits the collaboration between the CAVITY researchers, and supports visits and scientific meetings within the CAVITY project.

Are you working on any other joint project?

This paper is just a preliminary and preparatory study of the CAVITY project, which keeps researching the properties of void galaxies, such as kinematics, ionised gas, stellar populations, atomic and molecular gas, dark matter content, cosmological simulations, etc. Researchers from the University of Granada will keep collaborating with the University of Lyon 1 the following years, while the CAVITY project continues.