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  09.02.2021 - Testing the Cosmological Principle - Seminario 10 febbraio ore 16:00

Nell'ambito del Corso di Dottorato in Fisica e Nanoscienze, il 10 febbraio 2021, alle ore 16:00, il Prof. Subir Sakar (Università di Oxford) terrà un seminario online su ZOOM dal titolo:

Testing the Cosmological Principle

In the standard LCDM model of cosmology it is assumed that the universe is statistically isotropic and homogeneous when averaged on scales exceeding ~100 Mpc. The large dipole anisotropy of the CMB is explained as due to our local peculiar motion because of inhomogeneities. This kinematic interpretation requires that there be a corresponding dipole in the angular distribution of high redshift objects. Using a new all-sky catalogue of 1.4 million quasars we find that this hypothesis is rejected at 4.9σ by the observed matter dipole. This calls into question the standard practice of boosting to the `CMB frame' to analyse cosmological data. In the heliocentric frame the acceleration of the Hubble expansion rate is also found to be anisotropic with 3.9σ confidence. It can no longer be argued that this acceleration can be made to look isotropic by boosting to the CMB frame and thus interpreted as due to a Cosmological Constant.
[Astrophys. J. Lett. in press, arXiv:2009.14826; Astron. & Astrophys. 631 (2019) L19, arXiv:1808.04597]

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Coordinatore Prof. C. Corianò