The Euclid project

Cristobal Padilla

Euclid is a mission for the European Space Agency (ESA) Cosmic Vision (CV) 2015-25 programme to explore how the Universe evolved over the past 10 billion years to address questions related to fundamental physics and cosmology on the nature and properties of dark energy, dark matter and gravity, as well as on the physics of the early universe and the initial conditions which seed the formation of cosmic structure.

EUCLID GOALS

To accomplish its goals, Euclid will carry out a wide survey of 15,000 deg2 of the sky free of contamination by light from the Milky Way and the Solar System and a 40 deg2 deep survey to measure the high-redshift universe. The complete survey represents hundreds of thousands of images and several tens of Petabytes of data. Euclid will observe about 10 billion sources out of which more than one billion will be used for weak lensing. Several tens of million galaxy redshifts will be also measured and used for galaxy clustering. With these images Euclid will probe the expansion history of the Universe and the evolution of cosmic structures by measuring the modification of shapes of galaxies induced by gravitational lensing effects of dark matter and the 3-dimension distribution of structures from spectroscopic redshifts of galaxies and clusters of galaxies. Euclid data will provide improvement factors of ~30 in the measurement of the neutrino mass and up to ~400 in the uncertainty of the parameters of the cosmology state equation and will leave legacy catalogs in may areas of galaxy science with exquisite imaging quality and superb Near Infrared Spectroscopy.

Figure 1: The ESA Euclid mission designed and produced at IFAE.

EUCLID LAUNCH

The Satellite was launched on July 1st, 2023 from Cape Canaveral, Florida (US) with a Falcon 9 rocket from Space X. It has travelled 1.5 million kilometers up to the Lagrangian 2 point and has performed the commissioning and produced its first images, which show the spectacular capabilities of the instruments with an unprecedented resolution and wide angle field. This also demonstrates that the both instruments: a high quality panoramic visible imager (VIS), and a near infrared 3-filter photometer (NISP-P) and a slitless spectrograph (NISP-S) work as expected after the launch, including the NISP Filter Wheel Assembly (NISP-FWA) which has been the IFAE’s responsibility. The survey started in February 2024.

Figure 2: The ESA Euclid mission ready for launch.

Figure 3: The ESA Euclid mission launched into space on Saturday, July 1st on a SpaceX Falcon 9 rocket from Cape Canaveral Station in Florida, USA.

IFAE CONTRIBUTION IN 2023

During 2023, the group has continued activities inside the Euclid consortium to exploit the data and contribute to the scientific output of the mission. We have two PhD students concentrating in crucial aspects of the scientific analysis exploitation. One is measuring the photo-z distribution with a method that cross-correlates the redshift measurements with spectroscopic redshifts. The method will serve to verify the n(z) distribution and check for possible biases in this crucial ingredient for the extraction of the cosmological parameters with the first Euclid data release. The other student is applying unsupervised machine learning techniques to denoise the images and measure the galaxy shear, a crucial parameter in the weak-lensing signal of the Euclid project. Additionally, Cristobal Padilla is the chair of the Euclid Speaker’s Bureau and activities to build the software infrastructure to serve the consortium in this area have started within IFAE.

Figure 4: Euclid’s Early Release Observations include a number of scientifically exciting targets.

INFRA-RED DETECTOR CHARACTERIZATION

The ASTEROID H2020 was finished and a PhD thesis focusing on the characterization of the 2k^2 high performance Infrared Focal Plane Arrays produced by the project was also finalized. The project served to position IFAE’s Cosmology and Astronomical Hardware group as one of the few European groups able to work with characterization of detectors at the forefront of the technology.

Continuing these activities is the participation of the group in the EU project ATHENA, where it will be responsible for the characterization of Vey Long Wave Infra-Red detectors with p/n technology to be developed by CEA-Leti and Lynred. Additionally, the group will be responsible for the qualification and characterization of the IR detectors (H2RG from Teledyne) of the ARRAKIHS mission, the first ESA mission lead by Spain.