Euclid: ESA's mission to map the geometry of the dark universe

Abstract

Euclid is a space-borne survey mission developed and operated by ESA. It is designed to understand the origin of the Universe's accelerating expansion. Euclid will use cosmological probes to investigate the nature of dark energy, dark matter and gravity by tracking their observational signatures on the geometry of the Universe and on the history of structure formation. The mission is optimised for the measurement of two independent cosmological probes: weak gravitational lensing and galaxy clustering. The payload consists of a 1.2 m Korsch telescope designed to provide a large field of view. The light is directed to two instruments provided by the Euclid Consortium: a visual imager (VIS) and a near-infrared spectrometer-photometer (NISP). Both instruments cover a large common field of view of 0.54 deg 2 , to be able to survey at least 15,000 deg 2 for a nominal mission of 6 years. An overview of the mission will be presented: the scientific objectives, payload, satellite, and science operations. We report on the status of the Euclid mission with a foreseen launch in 2019.

Observational probes of cosmic acceleration

“…While BigBOSS, Euclid, and WFIRST all plan to measure BAO in the range 1 < z < 2, it is not clear that they can achieve f sky = 0.25 with nP ≈ 2 even collectively. Euclid plans to survey ≈ 14, 000 deg 2 over the range 0.7 < z < 2 in its 6.25-year primary mission, but the forecasts in Green et al (2012), which are based on the Euclid instrument sensitivity of Laureijs et al (2011) and the Hα luminosity function and galaxy bias measurements of Sobral et al (2013) and Geach et al (2012), imply that Euclid will reach nP < 0.5 at z > 1.2. BigBOSS plans to survey 14, 000 deg 2 in the northern hemisphere, and a southern hemisphere equivalent could increase the area to 24, 000 deg 2 (limited in the end by Galactic extinction).…”

“…Current incarnations of these plans are described in the Euclid Red Book (Laureijs et al, 2011) and the WFIRST Science Definition Team's final report (Green et al, 2012), though technical specifications and survey strategies may evolve to some degree prior to launch. The present baseline strategy for Euclid has a a survey area of approximately 14,000 deg 2 and redshift range 0.7 < z < 2.0, while the baseline strategy for WFIRST adopts a smaller area (3,400 deg 2 ), fainter flux limit, and higher redshift range (1.3 < z < 2.7).…”

“…Euclid plans to carry out optical and near-IR imaging and near-IR slitless spectroscopy over roughly 14,000 deg 2 , for weak lensing and BAO measurements. In its current design (Laureijs et al, 2011), Euclid utilizes a 1.2-meter telescope, a 0.56 deg 2 optical focal plane (604 million 0.10 ′′ pixels), and a near-IR focal plane with similar area but larger pixels (67 million 0.30 ′′ pixels). Well ahead of either Euclid or WFIRST, the European X-ray telescope eROSITA (on the Russian Spectrum Roentgen Gamma satellite) is expected to produce an all-sky catalog of ∼ 10 5 X-ray selected clusters, with X-ray temperature measurements and resolved profiles for the brighter clusters (Merloni et al, 2012).…”

Large-scale structure observations

“…Looking beyond these ground-based surveys, the ESA Euclid mission, with a nominal launch date of 2019, will revolutionise observational cosmology by conducting imaging and spectroscopic surveys that are approximately two orders of magnitude better than those currently available (Laureijs et al 2011). …”

Characterizing strong lensing galaxy clusters using the Millennium-XXL and moka simulations

“…SLCs are now well established as a promising class of objects that cannot be ignored in cosmology, and their future is extremely promising, since future facilities are expected to detect thousands of SLCs (Laureijs et al 2011;Boldrin et al 2012Boldrin et al , 2016Serjeant 2014), and the exquisite resolution of the James Webb Space Telescope (JWST) will deliver unique multi-colour data sets for some of them. The growing importance of SLCs has been recently illustrated by the CLASH program (Postman et al 2012) which has been awarded of 500 HST orbits to observe 25 massive SLCs.…”