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Teilchentee SS 2020
Thursday, 16:15 (Happy chatting, discussing etc commences at 16:00)
Date: 27.8.2020
Speaker: Mohamed Rameez
Title: The Cosmological principle and the frame that never was
Abstract
The largest anisotropic feature of the Cosmic Microwave Background is the dipole, believed to originate from the relative motion of the heliocentric frame with a velocity of ~369 km s^-1 with respect to the ‘rest frame of the Universe’ in standard cosmology. This should cause a dipolar modulation in the number counts of distant sources, through special relativistic aberration and Doppler boosting effects. We test this with various all-sky catalogues: NVSS and SUMSS radio galaxies, WISE galaxies and AGNs as well as GAIA-unWISE AGNs and consistently find a significantly larger dipole than expected, implying velocities > 1000 km s^-1 at conservative statistical significances as high as 3.3 sigma. These and other observations hint at a bulk flow of matter in the local Universe, extending out to scales larger than is typical in \Lambda CDM N-body simulations. Convergence to the CMB rest frame has never been demonstrated and this frame does not exist in any meaningful sense. An observational effect of such a bulk flow would be a scale dependent dipolar modulation in the deceleration parameter. We look for this in the SDSS-II/SNLS-III Joint lightcurve analysis compilation of SN1a data and find such a modulation at ~3.9 sigma statistical significance, while the evidence for any isotropic acceleration of the Universe simultaneously drops to <1.4 sigma. These observations suggest that dark energy is an artefact of our idealized cosmological model.
