Probing dipolar power asymmetry with galaxy clustering and intrinsic alignments
Phys. Rev. D 114, 043534 – Published 18 August, 2026
DOI: https://doi.org/10.1103/n2s7-fl28
Abstract
We investigate the prospects for probing large-scale power asymmetry through galaxy clustering and intrinsic alignments (IA) in stage IV galaxy surveys. Specifically, we consider a dipolar modulation in the primordial power spectrum and evaluate the Fisher information matrix using the two-point statistics of both the galaxy clustering and IA. Our analysis reveals that while IA alone provides limited improvement in constraining the modulation amplitude, the cross-spectrum between galaxy density and IA can contribute up to half the constraining power of galaxy clustering, especially for surveys with low galaxy bias and high number density of galaxies, such as Euclid. This demonstrates the potential of IA-clustering cross-correlations as a robust consistency check against systematics, and highlights the complementary roles of galaxy clustering and IA in constraining the asymmetry. We also show that marginalizing over galaxy bias and IA bias parameters has a negligible impact on the final constraint on the modulation amplitude.
