The kinetic Sunyaev-Zel'dovich effect from reionization: simulated full-sky maps at arcminute resolution

The kinetic Sunyaev–Zel'dovich (kSZ) effect results from Thomson scattering by coherent flows in the reionized intergalactic medium. We present new results based on ray-tracing an 8 Gpc/h realization of reionization with resolution elements 2 Mpc/h (subtending $\sim 1$′ at z = 6) on a side to create a full-sky kSZ map. The realization includes, self-consistently, the effects of reionization on scales corresponding to multipoles $10\lesssim \ell \lesssim 5000$. We separate the kSZ map into Doppler ($v$), Ostriker–Vishniac ($\delta v$), patchy ($xv$), and third-order ($x\delta v$) components, and compute explicitly all the auto- and cross-correlations (e.g., $⟨vv⟩$, $⟨\delta vxv⟩$, etc.) that contribute to the total power. We find a complex and nonmonotonic dependence on the duration of reionization at $\ell \sim 300$ and evidence for a non-negligible (10%–30%) contribution from connected four-point correlations, $⟨xvxv{⟩}_c$, usually neglected in analytical models. We also investigate the cross-correlation of linear matter and large-scale kSZ temperature fluctuations, focusing on (1) cross-power spectra with biased tracers of the matter density and (2) cold spots from infall onto large, rare H ii regions centered on peaks in the matter distribution at redshifts $z>10$ that are a generic non-Gaussian feature of patchy reionization. Finally, we show that the reionization history can be reconstructed at 5σ–10σ significance by correlating full-sky 21 cm maps stacked in bins with $\Delta \nu =10MHz$ with existing cosmic microwave background (CMB) temperature maps at $\ell <500$, raising the prospects for probing reionization by correlating CMB and LSS measurements. The resulting kSZ maps have been made publicly available at www.cita.utoronto.ca/∼malvarez/research/ksz-data/.