Constraints on modified gravity from the BOSS galaxy survey

Constraints on modified gravity from the BOSS galaxy survey by Lorenzo Piga et al. on Wednesday 23 November We develop a pipeline to set new constraints on scale-independent modified gravity, from the galaxy power spectrum in redshift space of BOSS DR12. The latter is modelled using the effective field theory of large-scale structure up to 1-loop order in perturbation theory. We test our pipeline on synthetic and simulated data, to assess systematic biases on the inferred cosmological parameters due to marginalization and theoretical errors, and we apply it to the normal branch of the DGP model with a $\Lambda$CDM background. We observe biased posteriors due to the strong degeneracy between the nDGP parameter $\Omega_{\rm rc}$ and the primordial amplitude of fluctuations $A_s$. Fixing the latter to the Planck central value, we obtain $\Omega_{\rm rc}\lesssim 0.2$ at 95$\%$ C.L. We also discuss a procedure to alleviate the prior dependence of this bound. arXiv: http://arxiv.org/abs/http://arxiv.org/abs/2211.12523v1