B. Sartoris, A. Biviano, C. Fedeli, J.G. Bartlett, S. Borgani, M. Costanzi, C. Giocoli, L. Moscardini, J. Weller, B. Ascaso, S. Bardelli, S. Maurogordato, P. T. P. Viana

Abstract
We study the characteristics of the galaxy cluster samples expected from the European Space Agency's Euclid satellite and forecast constraints on parameters describing a variety of cosmological models. In this paper we use the same method of analysis already adopted in the Euclid Red Book, which is based on the Fisher matrix approach. Based on our analytical estimate of the cluster selection function in the photometric Euclid survey, we forecast the constraints on cosmological parameters corresponding to different extensions of the standard Λ cold dark matter model. Using only Euclid clusters, we find that the amplitude of the matter power spectrum will be constrained to Δσ₈ = 0.0014 and the mass density parameter to ΔΩ_m = 0.0011. The dynamical evolution of dark energy will be constrained to Δw₀ = 0.03 and Δw_a = 0.2 with free curvature Ω_k, resulting in a (w₀, w_a) figure of merit (FoM) of 291. In combination with Planck cosmic microwave background (CMB) constraints, the amplitude of primordial non-Gaussianity will be constrained to Δf_NL ≃ 6.6 for the local shape scenario. The growth factor parameter γ, which signals deviations from general relativity, will be constrained to Δγ = 0.02, and the neutrino density parameter to ΔΩ_ν = 0.0013 (or Δ∑m_ν = 0.01). Including the Planck CMB covariance matrix improves dark energy constraints to Δw₀ = 0.02, Δw_a = 0.07, and a FoM = 802. Knowledge of the observable-cluster mass scaling relation is crucial to reach these accuracies. Imaging and spectroscopic capabilities of Euclid will enable internal mass calibration from weak lensing and the dynamics of cluster galaxies, supported by external cluster surveys.

Keywords
galaxies: clusters: general, cosmological parameters, cosmology: theory, dark energy, large-scale structure of Universe

Monthly Notices of the Royal Astronomical Society
Volume 459, Issue 2, Page 1764
2016 June

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