Testing the anisotropy of cosmic acceleration from Pantheon supernovae sample

Abstract

In this paper, we study the anisotropy of cosmic acceleration using the Pantheon sample, which includes 1048 spectroscopically confirmed Type Ia supernovae (SNe Ia) covering the redshift range 0.01 < z < 2.3. In hemisphere comparison method, we find the dipole direction is (l = 37 ± 40°, b = 33 ± 16°) with the maximum anisotropy level of δ = 0.136+0.009-0.005. From the dipole fitting method, we find that the magnitude of anisotropy is A = (3.7-3.7+2.5) × 10-4, and the direction of the dipole (l = 329°-28°+101°, b = 37°-21°+52°) in the galactic coordinate system. The result is weakly dependent on redshift from the redshift tomography analysis. The anisotropy is small and the isotropic cosmological model is an excellent approximation.