Anisotropy in Pantheon+ supernovae

Understand

We employ Maximum Likelihood Estimators to examine the Pantheon+ catalogue of Type Ia supernovae for large scale anisotropies in the expansion rate of the Universe.

• The analyses are carried out in the heliocentric frame, the CMB frame, as well as the Local Group frame.
• In all frames, the Hubble expansion rate in the redshift range 0.023 < z < 0.15 is found to have a statistically significant dipolar variation exceeding 1.5 km/s/Mpc, i.e.
• bigger than the claimed 1% uncertainty in the SH0ES measurement of the Hubble parameter H_0.