Equation 10 · From Origins to Frontier: A History of Precision Cosmology
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the reported a local. Read the equation part by part below; each part has a contextual explanation and a link to its mathematical background.
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The local, late-universe route to does not go through the CMB at all. It is built from a distance ladder: geometric parallax anchors the distance to nearby Cepheid variable stars, Cepheids calibrate the peak luminosity of Type Ia supernovae in the same host galaxies, and those calibrated supernovae are then used to measure distances — and thus the expansion rate — out to galaxies far enough that their recession velocity is dominated by cosmic expansion rather than local motion. The SH0ES team’s 2022 analysis, using Hubble Space Telescope observations of Cepheids in the hosts of forty-two Type Ia supernovae, reported a local of 73.04 ± 1.04 kilometers per second per megaparsec [ 7 ] .
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