### 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 ΛCDM model, including
massive neutrinos with total mass Mν, and to 3 extended
scenarios, including 1) additional relativistic degrees of freedom
(ΛCDM + Mν + Neff), 2) a deviation from
the cosmological constant (ΛCDM + Mν +
w0), and 3) a time-varying dark energy equation of state
parameter (ΛCDM + Mν + (w0,wa
)). 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 ns (σ(ns)=0.00085), the Hubble
constant H0 (σ(H0)=0.141 km/s/Mpc), the
total neutrino mass Mν (σ(Mν)=0.020
eV). Assuming dynamical dark energy we get
σ(Mν)=0.030 eV for the mass and
(σ(w0), σ(wa)) = (0.0214, 0.071) for
the equation of state parameters. The predicted sensitivity to
Mν 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.

Original language | English |
---|---|

Article number | 047 |

Pages (from-to) | 47 |

Journal | Journal of Cosmology and Astroparticle Physics |

Volume | 2019 |

Issue number | 2 |

DOIs | |

Publication status | Published - 22 Feb 2019 |

Externally published | Yes |

### Keywords

- Cosmological parameters from LSS
- Neutrino masses from cosmology

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## Cite this

Sprenger, T., Archidiacono, M., Brinckmann, T., Clesse, S., & Lesgourgues, J. (2019). Cosmology in the era of Euclid and the Square Kilometre Array.

*Journal of Cosmology and Astroparticle Physics*,*2019*(2), 47. [047]. https://doi.org/10.1088/1475-7516/2019/02/047