On the Way to the Most Precise Map of Our Universe

star-forming region Messier 78
star-forming region Messier 78
 

Observations made by the Euclid telescope show the world the discovery of free-floating new-born planets, of a new dwarf galaxy and many more. RWTH-Physicists are involved in the project.

The Euclid Consortium releases early scientific papers based on observations made by the Euclid telescope. A number of scientifically exciting targets have been observed and analyzed by scientists of the Euclid Collaboration during an Early Release Observations phase, giving a glimpse of the unprecedented power of this telescope meant to provide the most precise map of our Universe over time.

Involved in the massive project are Professor Julien Lesgourgues and Santiago Casas from the Chair of Theoretical Astroparticle and Cosmology Institute of Theoretical Particle Physics and Cosmology (TTK) of RWTH Aachen University.

"This first beautiful release of Euclid images confirms that the mission will be able to achieve one of its main targets over the next few years: to assemble a huge catalogue of images of about one billion galaxies - the largest galaxy image catalogue every obtained. With such a catalog, we will be able to understand the detailed formation process of large structures in our Universe - like cluster of galaxies, big filaments of matter and big voids - over the past billion years," says Professor Lesgourgues.

The distribution of dark matter and many more

Exciting scientific results about the discovery of free-floating new-born planets, the population of globular clusters around nearby galaxies, the discovery of new dwarf and low-surface brightness galaxies, the distribution of dark matter and intracluster light in clusters of galaxies, or high-redshift magnified lensed galaxies are described in a series of 10 scientific publications. In addition to these first and promising scientific results, the Consortium also publishes on this day the mission’s reference papers that confirm the outstanding performance of Euclid.


"What is particularly exciting for a theoretical cosmologist like me is that this should allow us to measure the mass of the lightest known particles, the neutrinos, and to better understand the properties of the two most mysterious constituents of the universe, dark matter and dark energy. Indeed, neutrinos, dark matter and dark energy are all very abundant in the Universe, and their properties - including the neutrino mass - determine the way in which these large structures form", Lesgourgues explains. "In order to measure the neutrino mass or determine the properties of dark matter and dark energy, we need to compare real data with many computer simulations of the Universe performed under various assumptions." In RWTH’s cosmology group, simulations play an important role.

The scientists from Aachen develop and provide to the international community of cosmologists some simulation codes that show how the large-scale Universe depends, among others, on the properties of neutrinos, dark matter and dark energy. "These tools will play an essential role in the comparison between real observations from Euclid and cosmological models. We have been preparing ourselves to analyze the Euclid data for many years, and we are thrilled to get a confirmation that the satellite instruments work as well as expected", Dr. Santiago Casas adds.

"Our work focuses on Bayesian parameter estimation, employing sophisticated statistical methods to fit the parameters of our model to observational data. These methods are computationally demanding, so we rely on the RWTH High Performance Computing Center to perform parts of these calculations. By simulating various scenarios and exploring different assumptions, we forecast the performance of the Euclid mission in measuring the cosmological parameters of our universe, such as the abundance of dark matter and dark energy. At RWTH, we have developed two widely recognized codes within the cosmological community - CLASS and MontePython - which play a key role in facilitating these analyses."

The Euclid Consortium

In collaboration with the European Space Agency (ESA), the Euclid Consortium has been planning, building, and is currently operating the Euclid space telescope mission. This mission aims at mapping the extragalactic sky over a period of six years, providing unique data that can offer new insights into dark energy and dark matter. Launched on July 1st, 2023, the telescope successfully began its cosmological survey on February 14th, 2024. The Euclid Consortium comprises more than 2600 members, including over 1000 researchers from more than 300 laboratories in 15 European countries, plus Canada, Japan and United States, covering various fields in astrophysics, cosmology, theoretical physics, and particle physics. Today, the efforts of the Collaboration can be shown through a first suite of Euclid publications.

An Early Release Observations program was conducted during Euclid’s first months in space as a first look at the depth and diversity of science Euclid will provide. A total of 24 hours was allocated towards specific targets chosen to produce stunning images, also relevant for scientific research. Five of these images were released in November, 2023. The remaining five are being published today, May 23rd, 2024, by ESA. The papers, which have all been subject to the internal peer review process, are available at Euclid Consortium Publications, and will appear as pre-publications on the ArXiv. The images and science-ready catalog are available for download from ESA.