Constraints on primordial non-Gaussianity from galaxy-CMB lensing cross correlation

Recent studies have shown that the primordial non-Gaussianity affects the clustering of dark matter halos through a scale-dependent bias, and various constraints on the non-Gaussianity through this scale-dependent bias have been placed. Here, we introduce the cross correlation between the CMB lensing potential and the galaxy angular distribution to effectively extract information about the bias from the galaxy distribution. Then, we estimate the error of the nonlinear parameter, f(NL), for the ongoing CMB experiments and galaxy surveys, such as Planck and Hyper Suprime-Cam. We found that for the constraint on f(NL) with Planck and Hyper Suprime-Cam, the wide field galaxy survey is preferable to the deep one, and the expected error on f(NL) can be as small as Delta f(NL) similar to 80 for b(0) = 2 and Delta f(NL) similar to 30 for b(0) = 4, where b(0) is the linear bias parameter. It is also found that a future wide field galaxy survey could achieve Delta f(NL) similar to 5 with cosmic microwave background prior to Planck, if one could observe highly biased objects at higher redshift (z similar to 2).