Primordial non-Gaussianities for nonsingular Horndeski cosmologies

We consider a novel bounce universe model constructed within the framework of Horndeski gravity. We have analyzed the bispectrum of primordial scalar perturbations and evaluated the corresponding non-Gaussianities for this specific model. The nonlinear parameter <a:math xmlns:a="http://www.w3.org/1998/Math/MathML" display="inline"><a:mrow><a:msub><a:mrow><a:mi>f</a:mi></a:mrow><a:mrow><a:mi>NL</a:mi></a:mrow></a:msub></a:mrow></a:math> was computed for various wave vector configurations, including: (i) the local configuration, (ii) the equilateral configuration, and (iii) the enfolded configuration, which is a linear combination of the equilateral and orthogonal shapes. We demonstrate that the observational constraints on the scalar spectrum index tilt and the scalar-to-tensor ratio, together with the unitarity bounds, ensure that the bounds from non-Gaussianities are trivially satisfied. Therefore, this particular bounce universe scenario is fully viable in light of modern observational data.