## Tensor-to-scalar ratio from SO

Simons Observatory aims to measure the tensor-to-scalar ratio, r, with σ(r) = 0.003 for an r = 0 model. This will enable at least a 3σ measurement of primordial gravitational waves if r ≥ 0.01. If SO sees no signal, this would exclude models with r ≥ 0.01 at more than 99% confidence.

Figure (1) shows a summary of SO forecasts for the primordial power spectrum parameters ns and r for two example cases: vanishingly small primordial tensor modes and primordial perturbations with r = 0.01. The contours correspond to 68% and 95% confidence levels. For each model the SO baseline (goal) forecasts are shown as filled (dashed) contours. In gray we show the current most stringent constraint in this parameter space (Planck TT,EE,EE+lowE+lensing + BICEP2/Keck + BAO).

## Primordial power spectrum from SO

Simons Observatory aims to estimate the primordial scalar amplitude at the half-percent level at scales (k = 0.2/Mpc) smaller than those accessible to the Planck satellite. This will test the almost-scale-invariant prediction of inflation over a wider range of scales than yet probed to this precision.

Figure (2) constraints on the primordial power exp(−2τ) P(k) from SO baseline (blue) and goal (orange) configurations, compared to estimated constraints from Planck temperature and polarization (yellow boxes). The largest improvement in the spectra is seen on small scales, where the error on the primordial power spectrum at k = 0.2 Mpc−1 improves by an order of magnitude thanks to the SO polarization data.

## Primordial non-Gaussianity from SO

Simons Observatory targets a measurement of the non-Gaussianity of the primordial perturbations at the σ(fNL local)=2 level, halving current constraints.

Simons Observatory targets a measurement of the non-Gaussianity of the primordial perturbations at the σ(fNL local)=2 level, halving current constraints.

Figure (3) shows constraint on local primordial non-Gaussianity expected from SO CMB lensing cross-correlated with LSST galaxy clustering, exploiting the large-scale scale-dependent bias effect from fNL. The gray dashed vertical line marks our primary forecasts, the horizontal line marks the fNL=1 target.