Testing the cosmological principle with quasars

The cosmological principle posits that the universe is homogeneous and isotropic on the large scales. In history, the cosmological principle was confirmed by various cosmological observations from CMB to large scale structure. However, several new challenges to the cosmological principle were reported in recent years, particularly in radio observations from overdispersed radio source counts to quasars. Here, we firstly present studies on the peculiar velocity of large-scale anisotropy by measuring the dipole signal from the DESI DR1 catalogue with a sample of 1 176 570 quasars (0.8 < z < 3.0). Our analysis reveals the peculiar velocity of |v| = 443.8 ± 204.1 km/s towards (l, b) = (107.4° ±86.8° ,28.4° ±45.2° ) in Galactic coordinates. The motion direction deviates from the CMB dipole (264.02°, 48.253°). The inferred velocity is consistent at the 1.56σ level with the value of 370 km/s from a purely kinematic interpretation of the CMB dipole. Based on the motion direction component analysis, we have not found any significant deviation from cosmological principle in current released quasars data.