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Paper: The TRGB and the Hubble Constant in 2017: TIPSNU
Volume: 514, Stellar Populations and the Distance Scale
Page: 143
Authors: Lee, M. G.; Jang, I. S.
Abstract: One of the most highly debated issues in modern cosmology is the value of the Hubble constant. Recent studies of the Hubble constant raised a possible conflict between measurements with classical distance ladders and measurements with inverse distance ladders, which is called the Hubble tension. TIPSNU is a project to improve the accuracy of SNe Ia using the Tip of the Red Giant Branch (TRGB), and to better understand the Hubble tension. We present a new TRGB calibration based on distance anchors with geometric distances. Then we provide a new SN Ia calibration based on the TRGB distances to SN Ia-host galaxies. Using this SN Ia calibration to the sample of SNe Ia at z < 0.1, we derive a value of the Hubble constant, H0 = 71.17 ± 1.66 (random) ± 1.87 (syst.), with a total uncertainty of 2.50 km s-1 Mpc-1 (±3.5%). This result is consistent with the value based on the recent Cepheid calibration of SNe Ia, increasing the Hubble tension. The accuracy of the TRGB will be improved with a larger number of geometric distance anchors including TRGB stars in the Milky Way, and the uncertainties in the Hubble constant will be reduced with a larger sample of SN Ia host galaxies with TRGB distances in the near future.
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