English (UK)
Almería, 26 May 2026
The galaxies in the Universe are not uniformly distributed, but rather organized into a grand structure known as the cosmic web, formed by clusters of galaxies connected by filaments and walls, between which lie vast, almost barren regions known as cosmic voids. Until now, most studies of the galaxies inhabiting these isolated environments have analyzed them by considering all their light as if it originated from a single point.
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This supercomputer simulation, which observes our cosmic neighborhood from the outside, is a realistic, data-driven reconstruction of the dark matter network that has guided galaxies to their current positions. Where enormous dark filaments intersect, bright galaxies cluster. Credit: Simulation and reconstruction – Steffen Hess and Francisco-Shu Kitaura (Leibniz Institute for Astrophysics Potsdam) / Visualization – Tom Abel and Ralf Kaehler (Stanford Kavli Institute for Particle Astrophysics and Cosmology) |
In the framework of the Calar Alto Void Integral-field Treasury surveY (CAVITY) project (PI: I. Pérez, University of Granada), a team led from the Institute of Astrophysics of Andalusia (IAA-CSIC) used integral field spectroscopy data entirely taken at Calar Alto to analyze, for the first time with this level of detail, how the cosmic environment influences the evolution of more than two hundred galaxies located inside cosmic voids. The cosmic voids are not fully empty, but they host fewer galaxies than the other regions of the Universe. Specifically, thanks to their very low density conditions, those environments constitute a unique laboratory to study how the environment influences the evolution of galaxies.
“Our results indicate that galaxies located in cosmic voids better preserve their gas and maintain more active star formation, especially in their outer regions and in galaxies in transition between spiral and elliptical galaxies,” says Ana Conrado, IAA-CSIC researcher who leads the work.
Until now, most research on galaxies in cosmic voids had focused on their integrated properties. “It would be like studying a city by only observing its brightness from space: we wouldn't be able to distinguish neighborhoods, streets, or areas with different characteristics,” explains IAA researcher and second author of the study, Rubén García Benito. However, galaxies are complex and heterogeneous systems. “To understand how they evolve, it is necessary to study how these properties change within each galaxy,” he adds.
To achieve this, the scientific team used integral field spectroscopy data from the PMAS instrument at the Calar Alto 3.5 m telescope. Thanks to these data, the team was able to analyze in detail the ionized gas of more than two hundred galaxies located in cosmic voids and compare it with that of galaxies located in other environments of the cosmic web. “The results show that galaxies in voids exhibit more intense star formation and less extinction, related to a lower amount of dust,” notes Rosa M. González, a researcher at the IAA-CSIC who is part of the team. The effect is especially evident in galaxies that are in transition between spiral and elliptical galaxies, suggesting that this evolutionary process occurs more slowly in cosmic voids. Furthermore, it has been observed that the most influenced parts are the outer regions, that is, the disks of spiral galaxies.
Furthermore, based on indirect measurements, the study suggests that galaxies located in voids contain a greater amount of gas, possibly because they conserve it better or because they receive a more continuous supply from their surroundings. “This could be because galaxies in voids evolve more slowly and with less disturbance, allowing them to conserve their gas and maintain star formation for longer,” notes Ana Conrado (IAA-CSIC).
The researcher also points out that "the results coincide with our previous work on the properties of stars in galaxies in vacuums," reinforcing the idea that the cosmic environment plays a key role in galactic evolution.
Jesús Aceituno, director of the observatory, concludes "CAVITY is a pioneer initiative aimed specifically at understanding how the large scale structure influences the formation and evolution of galaxies, as shown by this this new study based on data from CAVITY and CALIFA, another large legacy survey carried out at Calar Alto with a great success".
Galaxies discovered by the Sloan Digital Sky Survey (SDSS). The red dots are galaxies with redder starlight, indicating that they are older and often larger. The large-scale, web-like distribution of the galaxies is visible to the naked eye. A greater redshift corresponds to a greater distance from Earth, which is at the center of the image. The image shows galaxies located approximately 2 billion light-years away. Credit: M. Blanton and SDSS |
The Calar Alto Observatory is one of the infrastructures that belong to the national map of Unique Scientific and Technical Infrastructures (Spanish acronym: ICTS), approved on March 11th, 2022, by the Science, Technology and Innovation Policy Council (CPCTI).
CONTACTS:
Institute of Astrophysics of Andalusia (IAA-CSIC) - Ana Conrado
Calar Alto observatory (CAHA) - Gilles Bergond
COMMUNICATION- CALAR ALTO OBSERVATORY