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

Abstract

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 × unWISE we forecast an 18σ projected-field kSZ detection using data already in hand. Combining SO CMB maps and unWISE galaxy catalogs, we expect a 62σ 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 × VRO/Euclid (at 6σ) and of the kSZ — CMB weak lensing cross-correlation with SO (at 16σ). Finally, ≈ 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.

The Atacama Cosmology Telescope: DR6 Gravitational Lensing Map and Cosmological Parameters

“…The publicly released mass maps can be used for a variety of cross-correlations; those with galaxy surveys, for example, can produce improved constraints on local primordial non-Gaussianity f NL (Schmittfull & Seljak 2018;McCarthy et al 2023), as well as constraints on the amplitude of structure as a function of redshift σ 8 (z) (e.g., White et al 2022). The mass maps can be combined with measurements of the tSZ and kSZ effects along with X-ray measurements to study the thermodynamics of galaxy formation and evolution by supplementing electron pressure, density, and temperature measurements with gravitational mass on arcminute scales (Battaglia et al 2017;Bolliet et al 2023). They can also be used to study the nonlinear universe, providing an unbiased view of the distribution of voids and filaments (e.g., He et al 2018;Raghunathan et al 2020).…”

class_sz I: Overview

“…From these profiles, one can then compute the contributions to the angular power spectra of the kSZ effect based on a formula valid at small scales (see Ref. [29] for details).…”

“…As a last example, a unique feature of class_sz is the prediction for projected-field kSZ 2 -LSS power spectra (we refer to Ref. [29] for details).…”

Kinematic Sunyaev-Zel’dovich effect with ACT, DES, and BOSS: A novel hybrid estimator

“…This estimator can also be applied in Fourier space as demonstrated in [14]. The kSZ signal has also been measured using projected fields [4,5,15,16]. This method relies on cross-correlating the square of a CMB temperature map with a projected density map constructed from largescale structure tracers.…”