Constraints on anisotropic primordial non-Gaussianity from intrinsic alignments of SDSS-III BOSS galaxies

We measure the three-dimensional cross-power spectrum of galaxy density and intrinsic alignment (IA) fields for the first time from the spectroscopic and imaging data of SDSS-III BOSS galaxies, for each of the four samples in the redshift range 0.2 <z <0.75 . In the measurement we use the power-spectrum estimator, developed in our previous work, to take into account the line-of-sight dependent projection of galaxy shapes onto the sky coordinate and the E /B -mode decomposition of the spin-2 shape field. Our method achieves a significant detection of the E -mode power spectrum with the total signal-to-noise ratio comparable with that of the quadrupole moment of the galaxy density power spectrum, while the measured B -mode power spectra are consistent with a null signal to within the statistical errors for all the galaxy samples. We also show that, compared to the previous results based on the two-dimensional projected correlation function, our method improves the precision of the linear shape bias parameter estimation by up to a factor of two thanks to the three-dimensional information. By performing a joint analysis of the galaxy density and IA power spectra in the linear regime, we constrain the isotropic and anisotropic local primordial non-Gaussianities (PNGs) parameters, f_NL^{s =0} and f_NL^{s =2}, simultaneously, where the two types of PNGs induce characteristic scale-dependent biases at very large scales in the density and IA power spectra, respectively. We do not find any significant detection for both PNGs; the constraints f_NL^{s =0}=5 7_-29⁺³⁰ and f_NL^{s =2}=-6 7_-269⁺²⁸⁵ (68% credible interval), respectively. Our method paves the way for using the IA power spectrum as a cosmological probe for current and future galaxy surveys.