A Test of the Cosmological Principle with Quasars

We study the large-scale anisotropy of Universe by measuring dipole in angular distribution a flux-limited, all-sky sample 1.36 million quasars observed Wide-field Infrared Survey Explorer (WISE). This is derived from new CatWISE2020 catalog, which contains deep photometric measurements at 3.4 and 4.6 $\mu$m cryogenic, post-cryogenic, reactivation phases WISE mission. While direction quasar sky similar to that cosmic microwave background (CMB), its amplitude over twice as large expected, rejecting canonical, exclusively kinematic interpretation CMB with p-value $5\times10^{-7}$ ($4.9\sigma$ for normal distribution, one-sided), highest significance achieved date such studies. Our results are conflict cosmological principle, foundational assumption concordance $\Lambda$CDM model.