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Cosmic Expansion Anomalies as Seen by Baryon Acoustic Oscillations

Thursday, 12.07.2018 14:00

Speakers: Jarah Evslin ( Institute of Modern Physics, Lanzhou, China)
Place: Seminar room n. 117, Institute of Physics, Pod vodárenskou věží 1, Prague 8
Presented in English
Organisers: Department of Particle Theory and Phenomenology
There are at least two 3 sigma anomalies in the cosmic expansion rate. One is the discrepancy between the local Universe measurement of the Hubble constant by Riess et al and also using strong lensing time delays vs the best fit Planck result assuming LCDM. The other is the Lyman alpha forest Baryon Acoustic Oscillation (BAO) measurement, which disagrees with LCDM when combined with other BAO measurements or Planck. We note that unanchored BAO provides a robust geometric probe, free of all but the most basic cosmological assumptions. Using it, we find that if these anomalies are confirmed, the first necessarily implies a change in pre-recombination cosmology while the second implies dynamical dark energy between the redshifts z=2 and z=0.6.