Cosmological distance forecasts for the CSST Galaxy Survey using BAO peaks

Kavli Affiliate: Hu Zhan

| First 5 Authors: Feng Shi, Jieyi Tian, Zhejie Ding, Xiaohu Yang, Yizhou Gu

| Summary:

The measurement of cosmological distances using baryon acoustic oscillations
(BAO) is crucial for studying the universe’s expansion. The Chinese Space
Station Telescope (CSST) galaxy redshift survey, with its vast volume and sky
coverage, provides an opportunity to address key challenges in cosmology.
However, redshift uncertainties in galaxy surveys can degrade both angular and
radial distance estimates. In this study, we forecast the precision of BAO
distance measurements using mock CSST galaxy samples, applying a two-point
correlation function (2PCF) wedge approach to mitigate redshift errors. We
simulate redshift uncertainties of $sigma_0 = 0.003$ and $sigma_0 = 0.006$,
representative of expected CSST errors, and examine their effects on the BAO
peak and distance scaling factors, $alpha_perp$ and $alpha_parallel$,
across redshift bins within $0.0 < z leqslant 1.0$. The wedge 2PCF method
proves more effective in detecting the BAO peak compared to the monopole 2PCF,
particularly for $sigma_0 = 0.006$. Constraints on the BAO peaks show that
$alpha_perp$ is well constrained around 1.0, regardless of $sigma_0$, with
precision between 1% and 3% across redshift bins. In contrast,
$alpha_parallel$ measurements are more sensitive to increases in $sigma_0$.
For $sigma_0 = 0.003$, the results remain close to the fiducial value, with
uncertainties ranging between 4% and 9%; for $sigma_0 = 0.006$, significant
deviations from the fiducial value are observed. We also study the ability to
measure parameters $(Omega_m, H_0r_mathrm{d})$ using distance measurements,
proving robust constraints as a cosmological probe under CSST-like redshift
uncertainties.

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