New constraints on primordial non-Gaussianity from large-scale cross-correlations of CMB lensing and the cosmic infrared background
We present new constraints on the local-type primordial non-Gaussianity parameter, $f_\mathrm{NL}^\mathrm{local}$, through analysis of the scale-dependent bias effect on the cosmic infrared background (CIB). To avoid biases from galactic dust contamination on large scales, we use cross-correlations between the CIB and Planck cosmic microwave background (CMB) lensing maps to constrain non-Gaussianity. Our measurement employs new dust-cleaned CIB maps that have been designed to be unbiased on large scales, which allows us to improve our constraining power on $f_\mathrm{NL}^\mathrm{local}$ by a factor of $\sim 2$ over previous CIB analyses. We derive a constraint of $f_\mathrm{NL}^\mathrm{local}=43 \pm 23$, matching the precision of the tightest existing constraints from cross-correlation methods. Consistency- and null-tests demonstrate that our results are robust to modeling assumptions and residual dust contamination.