An effective description of Laniakea: impact on cosmology and the local determination of the Hubble constant
The study models Laniakea, the supercluster hosting our galaxy, as an ellipsoidal inhomogeneity with triaxial expansion. This model predicts line-of-sight dependent corrections to luminosity distances based on peculiar velocities within Laniakea. These corrections shift inferred Hubble constant values for supernovae and galaxy surveys, suggesting that Laniakea's gravitational backreaction worsens the existing cosmological tension.