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arXiv · 2412.04660

Measuring the Hubble constant through the galaxy pairwise peculiar velocity

Wangzheng Zhang·Ming-chung Chu·Shihong Liao·Shek Yeung·Hui-Jie Hu
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Abstract

The Hubble constant $H_0$, the current expansion rate of the universe, is one of the most important parameters in cosmology. The cosmic expansion regulates the mutually approaching motion of a pair of celestial objects due to their gravity. Therefore, the mean pairwise peculiar velocity of celestial objects, which quantifies their relative motion, is sensitive to both $H_0$ and the dimensionless total matter density $\Omega_m$. Based on this, using the Cosmicflows-4 data, we measured $H_0$ for the first time via the galaxy pairwise velocity in the nonlinear and quasi-linear range. Our results yield $H_0=75.5\pm1.4$ km s$^{-1}$ Mpc$^{-1}$ and $\Omega_m=0.311^{+0.029}_{-0.028}$ . The uncertainties of $H_0$ and $\Omega_m$ can be improved to around 0.6% and 2%, respectively, if the statistical errors become negligible in the future.

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Wangzheng Zhang, Ming-chung Chu, Shihong Liao, Shek Yeung, Hui-Jie Hu. 2024-12-05. Measuring the Hubble constant through the galaxy pairwise peculiar velocity. https://doi.org/10.3847/2041-8213%2Fad9aa7

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