ESA's Euclid space telescope has been providing valuable data from the depths of space for almost two years. With its help, the largest and most accurate 3D map of the universe to date is to be created, with billions of stars and galaxies. The data from Euclid is analysed by the international Euclid consortium, which also includes the research teams of Francine Marleau and Tim Schrabback at the University of Innsbruck.
On 25 Euclid images the team led by Francine Marleau has now discovered a total of 2,674 dwarf galaxies and created a catalogue of dwarf galaxy candidates. Using a semi-automatic method, the scientists have identified candidates and analysed and described them in detail. “Of the galaxies identified, 58% are elliptical dwarf galaxies, 42% are irregular galaxies and a few are rich in globular clusters (1%), galactic nuclei (4%) and a noticeable fraction (6.9%) of dwarfs with blue compact centres (6.9%),” say Marlon Fügenschuh and Selin Sprenger from Marleau's team.
Testing cosmological models
This study provides insights into insights into the morphology, distance, stellar mass, and environmental context of dwarf galaxies. As part of the Euclid project, Francine Marleau is investigating the formation and development of galaxies, especially dwarf galaxies, the most numerous galaxies in the Universe, whose abundance and distribution provide critical tests for cosmological models.
“We took advantage of the unprecedented depth, spatial resolution, and field of view of the Euclid Data. This work highlights Euclid’s remarkable ability to detect and characterise dwarf galaxies, enabling a comprehensive view of galaxy formation and evolution across diverse mass scales, distances, and environments”, emphasizes Francine Marleau from the Department for Astro- and Particle Physics.
Deep look into the universe
The European Space Agency's (ESA) Euclid space telescope was launched on 1 July 2023. Scientists hope to learn more about the previously unexplored dark matter and dark energy that make up the Universe. The data from Euclid is analysed by the international Euclid consortium. Over the next few years, the 1.2 metre diameter space telescope will create the largest and most accurate 3D map of the Universe and observe billions of galaxies. Euclid can use this map to reveal how the universe expanded after the Big Bang and how the structures in the Universe have developed. This gives scientists more clues to better understand the role of gravity and the nature of dark energy and dark matter.
Over 2,000 scientists from around 300 institutes and laboratories are jointly analysing the mission data, which are also supplemented by ground-based telescopes. The research teams of Tim Schrabback and Francine Marleau at the University of Innsbruck are significantly involved in the project.
Publication: Euclid: Quick Data Release (Q1) – A census of dwarf galaxies across a range of distances and environments. Francine Marleau et.al. 2025 [arXiv: 2503.15335]