Leandros Perivolaropoulos
Department of Physics, University of Ioannina, Greece
Ultralate transition of the strength of gravity as a resolution of the Hubble crisis: Observational hints and theoretical implications
Abstract: The 5σ mismatch of the measured value of the Hubble constant between observational probes calibrated at early times (sound horizon calibrated at z~1100) and late times (SnIa absolute magnitude calibrated at z<0.01) is currently the most significant challenge for the standard LCDM model. I discuss the potential of a sudden change of the strength of gravity occurring at some specific time during the last 150Myrs (z<0.01) to resolve this tension without affecting the other observational successes of the standard LCDM model. I also review the effects of such a transition on the growth rate of cosmological perturbations and show that the delay of this growth due to such a transition is consistent with indications for such a delayed growth coming from weak lensing and redshift space distortion cosmological observations. Finally, I discuss the consistency of such a transition with other astrophysical data including Tully-Fisher observations, galaxy survey data and solar system chronology. Theoretical models that are consistent with such a transition will also be discussed. Such models include an ultra-late decay of the false vacuum in the context of a scalar tensor modified gravity theory and a generalized symmetron screening mechanism based on an explicit symmetry breaking in addition to the standard spontaneous symmetry breaking mechanism.
یکشنبه 11 اردیبهشت 1401، ساعت 18:00
Sunday 1 May 2022 – 18:00 Tehran Time
اتاق سمینار مجازی –Virtual Seminar Room
https://vc.sharif.edu/ch/cosmology
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