Wednesday Colloquia

Challenging the cosmological standard model

by Prof. Subir Sarkar (University of Oxford)

Wednesday, February 8, 2023 from to (Asia/Kolkata)
at AG-66 and via ZOOM webinar ( Zoom link: )
Meeting ID: 979 6325 9354 Pass code: 04072020
In the ΛCDM cosmological model the universe is assumed to be isotropic & homogeneous when averaged on large scales. That the CMB has a dipole anisotropy is ascribed to our peculiar (non-Hubble) motion because of local inhomogeneity. There ought then to be a similar dipole in the sky distribution of high redshift sources. Using catalogues of radio sources & quasars we find that this standard expectation is rejected at >5σ, i.e. the distribution of distant matter is not isotropic in the ‘CMB frame’. This calls into question the standard practice of boosting to this frame to analyse cosmological data, in particular to infer an isotropic acceleration of the Hubble expansion rate from Type Ia supernovae, which is interpreted as due to Λ.