Constraints on Single-Field Inflation from the BOSS Galaxy Survey

Abstract

Non-local primordial non-Gaussianity (NLPNG) is a smoking gun of interactions in single-field inflationary models, and can be written as a combination of the equilateral and orthogonal templates. We present the first constraints on these from the redshift-space galaxy power spectra and bispectra of the Baryon Oscillation Spectroscopic Survey (BOSS) data. These are the first such measurements independent of the cosmic microwave background fluctuations. We perform a consistent analysis that includes all necessary nonlinear corrections generated by NLPNG, and vary all relevant cosmological and nuisance parameters in a global fit to the data. Our conservative analysis yields joint limits on the amplitudes of the equilateral and orthogonal shapes, $f_{\mathrm{NL}}^{\mathrm{equil}}=940\pm 600$, $f_{\mathrm{NL}}^{\mathrm{ortho}}=-170\pm 170$ (both at 68\% CL). These can be used to derive constraints on coefficients of the effective single-field inflationary Lagrangian; in particular, we find that the sound speed of inflaton fluctuations has the bound $c_s\ge 0.013$ at 95\% CL. Fixing the quadratic galaxy bias and cosmological parameters, the constraints can be tightened to $f_{\mathrm{NL}}^{\mathrm{equil}}=260\pm 300$, $f_{\mathrm{NL}}^{\mathrm{ortho}}=-23\pm 120$ (68\% CL).

Comments: 6+7 pages, 2+3 figures, 0+1 table, code available at github.com/Michalychforever/CLASS-PT, with custom MontePython likelihoods available at github.com/oliverphilcox/full_shape_likelihoods