Seminar:- Resolving the Hubble tension- Measuring the expansion rate of the Universe to 1%
The Lambda Cold Dark Matter(ΛCDM) cosmological model has been remarkably successful in explaining numerous observations at scales spanning many orders of magnitude. However, several challenges have recently emerged. One of the most prominent challenges for the ΛCDM model is the “Hubble tension”, where the Hubble constant(H₀) measured using Cepheid-calibrated distance ladder of type Ia supernovae and that extrapolated using ΛCDM from the cosmic microwave background disagree by 5 standard deviations. To confirm new physics beyond the ΛCDM model as the source of this disagreement, ruling out any unknown systematic in these measurements using another independent probe is crucial. Strong-lensing time delay is such a probe that can independently constrain H₀ to 1% precision in the future. The main barrier to achieving this 1% precision is constraining the total mass profile shape in the lens galaxies using non-lensing observables such as stellar dynamics to avoid potential systematic in the H₀ from mass model assumptions. The speaker will describe how to constrain this mass profile to 1% precision from large statistical samples discovered from current and future surveys, based on joint lensing and dynamical analysis of lens galaxies using data from the James Webb Space Telescope(JWST) and Hubble Space Telescope(HST). Constraining the total mass profile of ellipticals will also provide key insights into the astrophysics of massive galaxy formation, e.g., baryonic feedback and merger processes. Furthermore, the 1% measurement in H₀ will enable tighter constraints on the dark energy parameters from stage IV experiments.
時間:2023.12.06(三) 10:00
頻道:Zoom ID: 925-9961-4426
講者:Dr. Anowar SHAJIB (The University of Chicago)
語言:英語
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此活動由香港大學物理系主辦。