Seminars
A challenge to the cosmological standard model
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Europe/London
R22 Pickavance Lecture Theatre (RAL)
R22 Pickavance Lecture Theatre
RAL
Pickavance Lecture Theatre near main cafeteria
Description
Abstract: In the ΛCDM model, the Universe is assumed to be isotropic & homogeneous when averaged on large scales. That the Cosmic Microwave Background has a dipole anisotropy is interpreted as due to our peculiar (non- Hubble) motion because of local inhomogeneities. A concomitant dipole in the same direction is then predicted in the sky distribution of distant sources. Using catalogues of radio galaxies and quasars, we find that the expected amplitude of the matter dipole 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 acceleration of the Hubble expansion rate using Type Ia supernovae, which is then interpreted as due to a cosmological constant Λ.
About Speaker: Prof Subir Sarkar is an astroparticle physicist and cosmologist, known for his research on the dark sector and astroparticle physics. He has been at the Rudolf Peierls Centre for Theoretical Physics, Oxford University, since 1990, and was Head of the Oxford Particle Theory Group (2011-2019). He was also Niels Bohr Professor[1] at the Niels Bohr Institute, University of Copenhagen (2013-2018). Since 2021, he has been Emeritus Professor and Emeritus Fellow of Linacre College, Oxford. https://en.wikipedia.org/wiki/Subir_Sarkar
If you an not make it in person then Zoom room is - https://ukri.zoom.us/j/97807522273
