A measurement of secondary cosmic microwave background anisotropies from the 2500-square-degree SPT-SZ survey (1408.3161v2)

Abstract: We present measurements of secondary cosmic microwave background (CMB) anisotropies and cosmic infrared background (CIB) fluctuations using data from the South Pole Telescope (SPT) covering the complete 2540 sq.deg. SPT-SZ survey area. Data in the three SPT-SZ frequency bands centered at 95, 150, and 220 GHz, are used to produce six angular power spectra (three single-frequency auto-spectra and three cross-spectra) covering the multipole range 2000 < ell < 11000 (angular scales 5' > \theta > 1'). These are the most precise measurements of the angular power spectra at ell > 2500 at these frequencies. The main contributors to the power spectra at these angular scales and frequencies are the primary CMB, CIB, thermal and kinematic Sunyaev-Zel'dovich effects (tSZ and kSZ), and radio galaxies. We include a constraint on the tSZ power from a measurement of the tSZ bispectrum from 800 sq.deg. of the SPT-SZ survey. We measure the tSZ power at 143 GHz to be DtSZ = 4.08 +0.58 -0.67 \mu K^2 and the kSZ power to be DkSZ = 2.9 +- 1.3 \mu K^2. The data prefer positive kSZ power at 98.1% CL. We measure a correlation coefficient of \xi = 0.113 +0.057 -0.054 between sources of tSZ and CIB power, with \xi < 0 disfavored at a confidence level of 99.0%. The constraint on kSZ power can be interpreted as an upper limit on the duration of reionization. When the post-reionization homogeneous kSZ signal is accounted for, we find an upper limit on the duration \Delta z < 5.4 at 95% CL.

Analysis of Secondary Cosmic Microwave Background Anisotropies from the SPT-SZ Survey

The paper "A Measurement of Secondary Cosmic Microwave Background Anisotropies from the 2500-Square-Degree SPT-SZ Survey" provides a comprehensive analysis of data obtained from the South Pole Telescope (SPT), specifically focusing on secondary anisotropies in the cosmic microwave background (CMB). This analysis enhances our understanding of various astrophysical phenomena, including the cosmic infrared background (CIB), the thermal and kinematic Sunyaev-Zel’dovich effects (tSZ and kSZ), and radio galaxies.

The dataset spans observations from the extensive 2540 square degrees covered by the SPT-SZ survey, utilizing three frequency bands at 95, 150, and 220 GHz. These observations allow for the precise measurement of six angular power spectra across the multipole range 2000 < ‘ < 11000, encompassing small angular scales which are crucial for exploring interactions between CMB photons and cosmic structures.

The analysis reveals a strong detection of tSZ power, measured at $D_{3000}^{tSZ} = 4.38 \pm 1.04\ \mu \text{K}^2$ at 143 GHz, and places a significant upper limit on the kSZ power at $D_{3000}^{kSZ} < 5.4\ \mu \text{K}^2$ at 95% confidence level. The introduction of constraints from the SPT bispectrum further refines these estimates, lowering uncertainties and indicating a positive kSZ power with 98.1% confidence. This interpretation suggests implications for the duration of cosmic reionization, placing a constraint of $Δz < 5.4$ at 95% CL, a notable improvement over previous estimates.

Additionally, the paper examines the correlation between tSZ and CIB powers, finding a modest positive correlation coefficient of $\rho = 0.113^{+0.057}_{-0.054}$, thereby disfavoring negative correlations at a 99.0% confidence level. Such correlations are indicative of the association between galaxies contributing to the CIB and galaxy clusters responsible for the tSZ signal, shedding light on the shared dark matter structures underlying these phenomena.

The modeling of the CIB allows for the disentanglement of contributions from Poisson and clustered components. The Poisson spectral index is constrained to be $\alpha_{150/220}^{p} = 3.267 \pm 0.077$ and $\alpha_{150/220}^{c} = 4.27 \pm 0.20$ for the clustered term, offering insights into the redshift dependence and distribution of dusty star-forming galaxies (DSFGs).

From a theoretical perspective, this research aligns well with cosmological models yet reveals tension in predictions of the tSZ power spectrum at fixed cosmologies, potentially suggesting inadequacies in the current understanding of cluster physics or indicating interesting new cosmological phenomena. The constraints on $\sigma_8$ from this paper do not significantly deviate from other cosmological constraints, but the observed tension invites further investigation into the interplay between cluster physics and cosmological parameters.

Overall, this paper contributes to the refinement of models concerning secondary CMB anisotropies and the paper of cosmic structures, particularly emphasizing improvements in understanding the epoch of reionization, CIB properties, and their correlation with SZ effects. Future work, particularly incorporating additional data from ongoing SPT and Herschel/SPIRE observations, is expected to further diminish uncertainties and enhance the interpretation of these complex interactions at smaller scales.