TPPC weekly seminar: Subir Sarkar - CANCELLED AND POSTPONED TO NEXT TERM (tube and train strikes)

Wednesday 4 Oct 2023, 12:30 → 14:00 Europe/London

Strand Building, S7.06

Speaker: Subir Sarkar (Uni of Oxford)

Title: A Challenge to the Standard Cosmological Model

Abstract: In the ΛCDM cosmological model the Universe is assumed to be isotropic and homogeneous when averaged on large scales. That the CMB has a dipole anisotropy is interpreted as due to our peculiar (non-Hubble) motion because of local inhomogeneity. A similar kinematic dipole is then predicted in the sky distribution of sources at high redshift. Using catalogues of radio sources and 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 for analysis of cosmological data, in particular to infer an isotropic acceleration of the Hubble expansion rate from Type Ia supernovae, which is then interpreted as due to a Cosmological Constant Λ. [Astrophys.J.Lett. 937 (2022) L31, ibid 908 (2021) L51]