Résumé
The standard cosmological model assumes the Cosmological Principle. However, recent observations hint at possible violations of isotropy on large scales, possibly through late-time anisotropic expansion. Here we investigate the potential of cross-correlations between CMB lensing convergence κ and galaxy cosmic shear B-modes as a novel probe of such late-time anisotropies. Our signal-to-noise forecasts reveal that information from the κ-B cross-correlation is primarily contained on large angular scales (ℓ≲200). We find that this cross-correlation for a Euclid-like galaxy survey is sensitive to anisotropy at the percent level. Making use of tomography yields a modest improvement of ∼ 20% in detection power. Incorporating the galaxy E-B cross-correlations would further enhance these constraints.