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arXiv · 2207.14566

Forecasting the Cross-Correlation of the CSST galaxy survey with the FAST HI Intensity Map

Furen Deng·Yan Gong·Yougang Wang·Shuting Dong·Ye Cao·Xuelei Chen
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Abstract

The cross-correlation of optical galaxies with the neutral hydrogen (HI) radiation intensity can enhance the signal-to-noise ratio (SNR) of the HI intensity measurement. In this paper, we investigate the cross-correlation of the galaxy samples obtained by the spectroscopic survey of the China Space Station Telescope (CSST) with the HI Intensity mapping (IM) survey of the Five-hundred-meter Aperture Spherical Telescope (FAST). Using the IllusitrisTNG simulation result at redshift $0.2 \sim 0.3$, we generate mock data of the CSST survey and a FAST L-band drift scan survey. The CSST spectroscopic survey can yield a sample of galaxies with a high comoving number density of $10^{-2} (\unit{Mpc}/h)^{-3}$ at $z \sim 0.3$. We cross-correlate the foreground-removed radio intensity with the CSST galaxies, including both the whole sample, and red and blue galaxy sub-samples separately. We find that in all cases the HI and optical galaxies are well correlated. The total HI abundance can be measured with a high precision from this correlation. A relative error of $\sim 0.6\%$ for $\Omega_{\rm HI}$ could be achieved at $z\sim 0.3$ for an overlapping survey area of $10000 \unit{deg}^2$.

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Furen Deng, Yan Gong, Yougang Wang, Shuting Dong, Ye Cao, Xuelei Chen. 2022-07-29. Forecasting the Cross-Correlation of the CSST galaxy survey with the FAST HI Intensity Map. https://doi.org/10.1093/mnras%2Fstac2185

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