Cosmology in the era of Euclid and the Square Kilometre Array

Tim Sprenger; Maria Archidiacono; Thejs Brinckmann; Sébastien Clesse; Julien Lesgourgues

doi:10.1088/1475-7516/2019/02/047

paper

Cosmology in the era of Euclid and the Square Kilometre Array

arXiv:1801.08331 · doi:10.1088/1475-7516/2019/02/047

Abstract

Theoretical uncertainties on non-linear scales are among the main obstacles to exploit the sensitivity of forthcoming galaxy and hydrogen surveys like Euclid or the Square Kilometre Array (SKA). Here, we devise a new method to model the theoretical error that goes beyond the usual cut-off on small scales. The advantage of this more efficient implementation of the non-linear uncertainties is tested through a Markov-Chain-Monte-Carlo (MCMC) forecast of the sensitivity of Euclid and SKA to the parameters of the standard $Λ$ CDM model, including massive neutrinos with total mass $M_{ν}$ , and to 3 extended scenarios, including 1) additional relativistic degrees of freedom ( $Λ$ CDM + $M_{ν}$ + $N_{eff}$ ), 2) a deviation from the cosmological constant ( $Λ$ CDM + $M_{ν}$ + $w_{0}$ ), and 3) a time-varying dark energy equation of state parameter ( $Λ$ CDM + $M_{ν}$ + $(w_{0}, w_{a})$ ). We compare the sensitivity of 14 different combinations of cosmological probes and experimental configurations. For Euclid combined with Planck, assuming a plain cosmological constant, our method gives robust predictions for a high sensitivity to the primordial spectral index $n_{s}$ ( $σ (n_{s}) = 0.00085$ ), the Hubble constant $H_{0}$ ( $σ (H_{0}) = 0.141 km/s/Mpc$ ), the total neutrino mass $M_{ν}$ ( $σ (M_{ν}) = 0.020 eV$ ). Assuming dynamical dark energy we get $σ (M_{ν}) = 0.030 eV$ for the mass and $(σ (w_{0}), σ (w_{a})) = (0.0214, 0.071)$ for the equation of state parameters. The predicted sensitivity to $M_{ν}$ is mostly stable against the extensions of the cosmological model considered here. Interestingly, a significant improvement of the constraints on the extended model parameters is also obtained when combining Euclid with a low redshift HI intensity mapping survey by SKA1, demonstrating the importance of the synergy of Euclid and SKA.

50 pages, 11 figures, 8 tables. v2: improved treatment of neutrino. v3: updated Euclid sensitivity settings, matches accepted version

Cosmology in the era of Euclid and the Square Kilometre Array

Abstract

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