Coffee talks
Friday 22/03/2024 @ 11:30, Sala riunioni quarto piano e on-line (meet.google.com/sue-bwvk-axf)
Sebastian von Hausegger (University of Oxford), "The cosmic matter dipole"
The ever-growing quantity and quality of astronomical data today has underpinned both the LCDM model of cosmology and general relativity as effective working theories. This same data also makes possible to perform tests of fundamental assumptions of this model. For instance, the measurement of the kinematic dipole in the distribution of matter and its comparison with that seen in the CMB constitutes a consistency check of the cosmological principle — the assumption of statistical homogeneity and isotropy. Having compiled an even catalog of almost 2 million distant AGN, we perform this check and uncover a matter dipole roughly aligned with the CMB dipole, however with an excess amplitude that is discrepant with the standard expectation at greater than 5 standard deviations. I will present background and results, and discuss developments since the initial publication. As these results reopened questions regarding the isotropy of the Universe, I will close with a brief overview of some anisotropic or inhomogeneous cosmological models.