The Euclid Mission

Euclid is an ESA-led medium class space mission selected in October 2011, with launch planned for 2022. The Euclid mission aims at understanding why the expansion of the Universe is accelerating and what is the nature of the source - commonly called dark energy - responsible for this acceleration. Dark energy represents around 75% of the energy content of the Universe today, and together with dark matter it dominates the Universe's matter-energy content. Understanding dark energy is one of the key goals of physics over the next decade. The imprints of dark energy and gravity will be tracked by Euclid using two complementary cosmological probes to capture signatures of the expansion rate of the Universe and the growth of cosmic structures: weak gravitational lensing; and galaxy clustering (both through baryonic acoustic oscillations and redshift-space distortions).

Although low-redshift cosmology is the primary driver of the mission, a wide range of science will be possible with the Euclid data. The Euclid Mission aims to survey over 15,000 deg^2 of the extragalactic sky with imaging in a wide visible (riz) band at 0.1" resolution, near-infrared photometry (Y, J, and H) and near-infrared spectroscopy. As a result, the Euclid Mission will generate a vast data set for legacy science, including broadband visible images and near-infrared photometry of roughly 1.5 billion galaxies and near-infrared spectroscopy of roughly 25 million galaxies. Such a large data set will touch on many aspects of astrophysics, on many different scales, from the formation and evolution of galaxies down to the detection of brown dwarfs.

In 2016, Canada joined the Euclid Consortium when CFHT approved the Canada-France Imaging Survey (CFIS) as a Large Program. CFIS, along with other ground-based surveys, will be used by Euclid to measure photometric redshifts in the northern sky. 27 faculty-level astronomers in Canada are members of the Euclid Consortium. In this white paper, we present a status update for Euclid, and a request that the committee make a strong recommendation that funds be allocated to support the exploitation of the Euclid data by Canadian researchers.