Forecast of cross-correlation of CSST cosmic shear tomography with AliCPT-1 CMB lensing

We present a forecast study on the cross-correlation between cosmic shear tomography from the Chinese Survey Space Telescope (CSST) and CMB lensing from Ali CMB Polarization Telescope (AliCPT-1) in Tibet. The correlated galaxy and CMB lensing signals were generated from Gaussian realizations based on inputted auto- and cross-spectra. To account for the error budget, we considered the CMB lensing reconstruction noise based on the AliCPT-1 lensing reconstruction pipeline; shape noise of the galaxy lensing measurement; CSST photo-\(z\) error; photo-\(z\) bias; intrinsic alignment effect, and multiplicative bias. The AliCPT-1 CMB lensing mock data were generated according to two experimental stages, namely the ``4 modules*yr'' and ``48 modules*yr'' cases. We estimate the cross-spectra in 4 tomographic bins according to the CSST photo-\(z\) distribution in the range of \(z\in[0,4)\). After reconstructing the pseudo-cross-spectra from the realizations, we calculate the signal-to-noise ratio (SNR). By combining the 4 photo-\(z\) bins, the total cross-correlation SNR\(\approx15\) (AliCPT-1 ``4 modules*yr'') and SNR\(\approx22\) (AliCPT-1 ``48 modules*yr''). Finally, we study the cosmological application of this cross-correlation signal. Excluding intrinsic alignment (IA) in the template fitting would lead to roughly a \(0.6\sigma\) increment in \(\sigma_8\) due to the negative IA contribution to the galaxy lensing data. For AliCPT-1 first and second stages, the cross-correlation of CSST cosmic shear with CMB lensing gives errors on the clustering amplitude \(\sigma_{\sigma_8}=^{+0.043}_{-0.038}\) or \(\sigma_{S_8}=\pm 0.031\) and \(\sigma_{\sigma_8}=^{+0.030}_{-0.027}\) or \(\sigma_{S_8}=\pm 0.018\), respectively.