New JWST Results: Is the Current Tension in Ho Signaling New Physics
ORAL · Invited
Abstract
The question of whether there is new physics beyond our current standard model, Lambda Cold Dark Matter (LCDM), is a crucial unresolved issue in cosmology today. Recent measurements of the Hubble constant (Ho) using Cepheids and Type Ia supernovae (SNe) appear to differ significantly (5-sigma) from values inferred from the cosmic microwave background (CMB) fluctuations. This discrepancy, if real, could indicate new physics beyond the standard model. In this talk, I will present new results from a James Webb Space Telescope (JWST) program designed to measure Ho, and aimed at reducing current systematic uncertainties. It utilizes three independent methods for measuring the distances to (the same) nearby galaxies that provide a calibration for SNe: Cepheid variables, Tip of the Red Giant Branch (TRGB) stars and J-Region Asymptotic Giant Branch (JAGB) stars. The Near-Infrared Camera on JWST has four times the resolution and ten times the sensitivity of HST in the near infrared, and is critical for ascertaining whether new physics is required beyond the standard model of cosmology.
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Publication: Freedman, W. L. and Madore, B. F., "Progress in direct measurements of the Hubble constant", Journal of Cosmology and Astroparticle Physics, vol. 2023, no. 11, 2023. doi:10.1088/1475-7516/2023/11/050.<br>Lee, A. J., Freedman, W. L., Jang, I. S., Madore, B. F., and Owens, K. A., "First JWST Observations of JAGB Stars in the SN Ia Host Galaxies: NGC 7250, NGC 4536, NGC 3972", arXiv e-prints, 2024a. doi:10.48550/arXiv.2312.02282.; Lee et al. 2024b, "JWST Observations of JAGB Stars in 11 Galaxies", in preparation<br>Owens, K. A., et al. 2024a " JWST Observations of Cepheids in NGC 7250," ApJ, submitted, 2024b in preparation<br>Hoyt, T. J., et al. 2024a, "JWST Observations of TRGB Stars", ApJ, submitted; 2024b in preparation<br>Freedman, W.L. et al. (2024), "The Hubble Constant from 3 Independent Methods Based on JWST Observations", in preparation<br>
