The Largest Synthetic Galaxy Catalogue

A picture excerpted from Euclid’s Flagship’s simulated catalogue. Each dot represents a galaxy: the blue dots show the galaxies in the middle of the dark matter’s clusters, whereas the red dots indicate the satellite galaxies. Together they trace the mass distribution of the Universe on a large scale, revealing clusters, [galaxy] filaments and cosmic void (Photo by: Jorge Carretero and Paul Tallada of the Port d’Informació Cientifica / Euclid Consortium; elaborated by Software Splotch)

The Euclid Consortium has released the largest synthetic galaxy catalogue ever created.  Named “Flagship 2 Galaxy Mock”, it includes more than 3.4 billion synthetic galaxies. Its purpose is to duplicate the actual Universe and to reproduce what Euclid telescope is going to observe in the coming years.

Launched in July 2023, Euclid Mission of the European Space Agency (ESA) aims to map more than one third of the sky in six years. Meanwhile, by reproducing the Universe through numerical simulations before having the final 3D map, scientists can better interpret Euclid’s observations.

In this way, scientists will be able to study the origin of the “cosmic web” – the structure of the Universe on a large scale -, to test the standard cosmological mock and to understand the nature of the dark energy and of the dark matter. Furthermore, the new synthetic catalogue can be used to study the galaxies’ evolution and to understand how galaxies originate and evolve during their life.

In its entirety, “Flagship 2 Galaxy Mock” includes 3.4 billion galaxies, each described by more than 400 physical properties, including luminosity, position, velocity and shape. This makes it possible to accurately reproduce the emergence of the large-scale structure of the universe: galaxies and galaxy clusters within the cosmic web which includes both dark and visible matter.

Creating a catalogue with such characteristics is both a scientific and technological challenge: it requires the development of computational and statistical strategies, in addition to the integration of the most recent knowledge about the formation and evolution of the galaxies and their interaction with the “dark” components of the Universe.

The catalogue “Flagship 2 Galaxy Mock” was created by an international teamwork, led by the Institute of Space Science (ICE-CSIC) and by the Port d’Informació Cientifica (PIC, the Scientific Information Harbour) in Barcelona (Spain), with the participation of six more European universities and research institutions.

The University of Bologna, through its Department of Physics and Astronomy “Augusto Righi” (DIFA), was among the founders and key contributors of the mission which led to the development of Euclid. This journey started in 2007 with the SPACE Project (Spectroscopic All-sky Cosmic Explorer), presented by an international group led by Professor Cimatti within the scope of the ESA’s space programme Cosmic Vision 2015-2025.