Projected-field kinetic Sunyaev-Zel'dovich Cross-correlations: halo model and forecasts

The kinetic Sunyaev-Zel'dovich (kSZ) effect, i.e., the Doppler boost of cosmic microwave background (CMB) photons caused by their scattering off free electrons in galaxy clusters and groups with non-zero bulk velocity, is a powerful window on baryons in the universe. We present the first halo-model computation of the cross-power spectrum of the projected-field kSZ signal with large-scale structure (LSS) tracers. We compare and validate our calculations against previous studies, which relied on N-body-calibrated effective formulas rather than the halo model. We forecast results for CMB maps from the Atacama Cosmology Telescope (AdvACT), Simons Observatory (SO), and CMB-S4, and LSS survey data from the Dark Energy Survey, the Vera C. Rubin Observatory (VRO), and Euclid. In cross-correlation with galaxy number density, for AdvACT x unWISE we forecast an 18o-projected-field kSZ detection using data already in hand. Combining SO CMB maps and unWISE galaxy catalogs, we expect a 62o-detection, yielding precise measurements of the gas density profile radial slopes. Additionally, we forecast first detections of the kSZ - galaxy weak lensing cross-correlation with AdvACT x VRO/Euclid (at 6a) and of the kSZ - CMB weak lensing cross-correlation with SO (at 16a). Finally, approximate to 10-20% precision measurements of the shape of the gas density profile should be possible with CMB-S4 kSZ - CMB lensing cross-correlation without using any external datasets.

Automated summary

The kinetic Sunyaev-Zel'dovich (kSZ) effect, which is the Doppler boost of cosmic microwave background (CMB) photons caused by their scattering off free electrons in galaxy clusters and groups with non-zero bulk velocity, provides valuable insights into baryons in the universe. This study presents the first halo-model computation of the cross-power spectrum of the projected-field kSZ signal with large-scale structure (LSS) tracers and compares and validates the calculations against previous studies. The results include forecasted measurements from CMB maps and LSS survey data, demonstrating the potential for precise measurements of gas density profile and cross-correlation with other observables.