Santiago Casas, Euclid Consortium Meeting, Oslo 2022

f(R) Hu-Sawicki model

Modification of the Einstein-Hilbert action

Induces changes in the gravitational potentials *

Scale-dependent growth of matter perturbations

Small changes in lensing potential

Free parameter: $f_{R0}$

$\lambda_C =32 \rm{Mpc}\sqrt{|f_{R0}|/10^{-4}}$

"Fifth-force" scale for cosmological densities

Hu, Sawicki (2007)

Santiago Casas, Euclid Consortium Meeting, Oslo 2022

f(R) Hu-Sawicki model

Codes used: for background and scale-dependent linear perturbations: MGCAMB and EFTCAMB

For non-linear power spectrum:

Winther et al (2019) fitting formula

Euclid: Spectroscopic and Photometric probes

• Spectroscopic Galaxy clustering: Take into account non-linear effects and scale-dependent growth
• 3x2pt photometric probe (WL+GCph+XCph), deeply non-linear regime
• Optimistic and Pessimistic Euclid IST:F settings. 3 Fiducial models.
• Forecast code validation:
  SOAPFish (Sapone), Fishermathica (Casas), STAFF (Cardone), CCCP (Camera), CosmicFish (Casas, Martinelli)

Santiago Casas, Euclid Consortium Meeting, Oslo 2022

Fisher Forecast results

Santiago Casas, Euclid Consortium Meeting, Oslo 2022

 $\sigma_{\log f_{R0}}=0.05$ (0.9%)

Full probe combination, optimistic Euclid constraints:

$f_{R0}=(5.0^{+ 0.58}_{-0.52} \times 10^{-6})$

Paper also contains impact of:

• Non-linear scales
• Cross-correlations
• Pessimistic settings
• LCDM-limit

Santiago Casas, Euclid Consortium Meeting, Oslo 2022

Thanks!

Gracias!

Tusen takk!