We place new constraints on the primordial local non-Gaussianity parameter $f_{\mathrm{NL}}$ using recent cosmic microwave background anisotropy and galaxy clustering data. We model the galaxy power spectrum according to the halo model, accounting for a scale-dependent bias correction proportional to $f_{\mathrm{NL}}/k^2$. We first constrain $f_{\mathrm{NL}}$ in a full 13 parameters analysis that includes 5 parameters of the halo model and 7 cosmological parameters. Using the WMAP7 CMB data and the SDSS DR4 galaxy power spectrum, we find $f_{\mathrm{NL}}={171}_{-139}^{+140}$ at 68% C.L. and $-69<f_{\mathrm{NL}}<+492$ at 95% C.L. We discuss the degeneracies between $f_{\mathrm{NL}}$ and other cosmological parameters. Including SN-Ia data and priors on $H_0$ from Hubble Space Telescope observations we find a stronger bound: $-35<f_{\mathrm{NL}}<+479$ at 95%. We also fit the more recent SDSS DR7 halo power spectrum data finding, for a $\Lambda \mathrm{CDM}+f_{\mathrm{NL}}$ model, $f_{\mathrm{NL}}=-93\pm 128$ at 68% C.L. and $-327<f_{\mathrm{NL}}<+177$ at 95% C.L. We finally forecast the constraints on $f_{\mathrm{NL}}$ from future surveys as EUCLID and from CMB missions as Planck showing that their combined analysis could detect $f_{\mathrm{NL}}\sim 5$.

• Received 17 May 2010

DOI:https://doi.org/10.1103/PhysRevD.82.083511