SPT-3G D1: A Measurement of Secondary Cosmic Microwave Background Anisotropy Power

TL;DR

This paper presents new millimeter-wave temperature power spectrum measurements from the South Pole Telescope, constraining secondary anisotropies like SZ effects, and inferring reionization duration with implications for cosmic history.

Contribution

It provides the first detailed constraints on thermal and kinematic SZ effects using multi-year SPT-3G data, including modeling of SZ-CIB correlations and reionization implications.

Findings

Thermal SZ power at 143 GHz: 4.91±0.37 μK² at ℓ=3000

Kinematic SZ power at 143 GHz: 1.75±0.86 μK² at ℓ=3000

Reionization duration limits: Δz_re < 3.8 to 6.1 depending on model

Abstract

We report new measurements of millimeter-wave temperature power spectra in the angular multipole range $1700 \le \ell \le 11,000$ (wavelengths $13^\prime \gtrsim \lambda \gtrsim 2^\prime$). We use two years of data in three observing bands centered near 95, 150, and 220 GHz from the SPT-3G receiver on the South Pole Telescope that cover a 1646 deg$^2$ region of the Southern sky. Using the measured power spectra, we present constraints on the thermal and kinematic Sunyaev-Zel'dovich (SZ) effects, radio galaxies, and cosmic infrared background (CIB). We find that inferred SZ powers are dependent on the detailed modeling of the thermal SZ-CIB correlation, and to a lesser extent on the assumed angular dependence of the SZ spectra. We report constraints for simulation-based model templates as well as fits where the angular dependencies of the SZ and CIB power spectra are allowed to vary. In the latter case at $\ell=3000$, we find thermal SZ power at 143 GHz of $D_{3000}^{\rm tSZ} = 4.91\pm0.37\, \mu{\rm K}^2$ and kinematic SZ power of $D_{3000}^{\rm kSZ} =1.75\pm0.86\, \mu{\rm K}^2$. We use the measured kinematic SZ power to estimate the duration of reionization, noting that the reionization inferences are sensitive to the model choices and assumed level of homogeneous kinematic SZ power from the late-time universe. We find a 95% limit on the duration from an ionization fraction of 25% to 75% of $\Delta^{50} z_{\rm re} <\,3.8$ based on a semi-analytic model, or a limit on the duration from an ionization fraction of 5% to 95% of $\Delta^{90} z_{\rm re} <\,6.1$ based on the AMBER simulations.