Speaker
Description
Local primordial non-Gaussianity, parametrized by $f_{NL}^{\mathrm{loc}}$, induces a characteristic scale dependence in the large-scale bias of halos. This scale dependence is a promising path to constrain multi-field inflation theories, which predict non-zero $f_{NL}^{\mathrm{loc}}$. We use the cosmic infrared background (CIB), measured by $\textit{Planck}$, which is sourced by thermal emission from dust grains in star-forming galaxies, to constrain the scale dependent bias and thus $f_{NL}^{\mathrm{loc}}$. As the CIB is difficult to separate from the dust emission in our own galaxy, we use the cross-correlation with the CMB lensing map of $\textit{Planck}$ to isolate the cosmological signal and thus use only information from the cross power spectra $C_\ell^{\nu\kappa}$ on large scales. We find no evidence for primordial non-Gaussianity and find $−87<f_{NL}^{\mathrm{loc}}<19$ with a Gaussian $\sigma(f_{NL}^{\mathrm{loc}})≈41$, assuming universality of the halo mass function. We present forecasts for future CMB lensing data sets, finding that Simons Observatory and CMB-S4 could achieve $\sigma(f_{NL}^{\mathrm{loc}})$ of 23 and 20 respectively. We find that, while the CIB contains significant information on $f_{NL}^{\mathrm{loc}}$ , its constraining power is severely limited by large-scale effects caused by the galactic dust-cleaning techniques in the CIB maps.
