Sat Sep 27 07:10:00 UTC 2025: **FOR IMMEDIATE RELEASE**
**Euclid Consortium Unveils Flagship 2: Largest Universe Simulation Ever Created**
**ZURICH, SWITZERLAND** – The Euclid Consortium today announced the release of Flagship 2, an unprecedentedly large and detailed simulation of the Universe. Containing 3.4 billion galaxies, each meticulously modeled with 400 distinct properties, Flagship 2 is designed to be a crucial tool in interpreting the vast datasets being produced by the European Space Agency’s (ESA) Euclid space telescope.
Launched in June 2023, Euclid is mapping the cosmos with unparalleled resolution. The sheer volume of data it generates requires sophisticated methods for analysis, and Flagship 2 provides the necessary framework.
Developed using an algorithm created by University of Zurich (UZH) astrophysicist Joachim Stadel, the simulation was run on the Piz Daint supercomputer at the Swiss National Supercomputing Centre (CSCS) in 2019. At the time, Piz Daint was among the world’s most powerful supercomputers, with over 80% of its capacity dedicated to this single project. The computation tracked the gravitational interactions of four trillion particles, subsequently populated with galaxies mirroring what Euclid is expected to observe.
“These simulations are crucial for preparing the analysis of Euclid’s data,” said Julian Adamek of UZH’s Department of Astrophysics, a collaborator on the project. “Euclid produces data in such sheer volume and speed that they must first be processed automatically. The methodology for interpreting these data had to be developed in advance – using simulations.”
Based on the standard cosmological model, Flagship 2 incorporates current knowledge of the Universe’s composition and evolution. While researchers expect Euclid’s observations to largely confirm the simulation’s predicted matter distribution, they are also anticipating potential surprises.
“We already see indications of cracks in the standard model,” said Stadel. “Euclid may reveal further phenomena that cannot be explained within the current theoretical framework.” The mission is particularly focused on unraveling the mysteries of dark energy, the force driving the Universe’s accelerating expansion.
Euclid’s high-resolution observations allow for the detection of subtle distortions in galaxy images caused by gravitational lensing, revealing the distribution of dark matter. Spectroscopic measurements will also enable precise distance determinations, creating a three-dimensional map of galaxies spanning a cosmic sphere with a 10-billion-light-year radius.
The Euclid Consortium also anticipates uncovering rare cosmic events thanks to the telescope’s wide-ranging survey.
Euclid released its first observational data in March 2025, offering new insights into the cosmic web and galaxy clusters. Further datasets are planned for publication in spring 2026.
The Flagship 2 galaxy mock catalogue is described in a paper by Castander, F., Fosalba, P., Stadel, J. et al (2025) published in Astronomy & Astrophysics, 697, A5. DOI:10.1051/0004-6361/202450853
**About the Euclid Consortium:**
The Euclid Consortium is a collaboration of scientists and engineers from across Europe and around the world, dedicated to the success of the Euclid mission.
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