A Comparison of Maps and Power Spectra Determined from South Pole Telescope and Planck Data

Abstract

We study the consistency of 150 GHz data from the South Pole Telescope (SPT) and 143 GHz data from the Planck satellite over the patch of sky covered by the SPT-SZ survey. We first visually compare the maps and find that the residuals appear consistent with noise after accounting for differences in angular resolution and filtering. We then calculate (1) the cross-spectrum between two independent halves of SPT data, (2) the cross-spectrum between two independent halves of Planck data, and (3) the cross-spectrum between SPT and Planck data. We find that the three cross-spectra are well fit (PTE = 0.30) by the null hypothesis in which both experiments have measured the same sky map up to a single free calibration parameter-i.e., we find no evidence for systematic errors in either data set. As a by-product, we improve the precision of the SPT calibration by nearly an order of magnitude, from 2.6% to 0.3% in power. Finally, we compare all three cross-spectra to the full-sky Planck power spectrum and find marginal evidence for differences between the power spectra from the SPT-SZ footprint and the full sky. We model these differences as a power law in spherical harmonic multipole number. The best-fit value of this tilt is consistent among the three cross-spectra in the SPT-SZ footprint, implying that the source of this tilt is a sample variance fluctuation in the SPT-SZ region relative to the full sky. The consistency of cosmological parameters derived from these data sets is discussed in a companion paper.

Assessing Consistency between WMAP 9 Year and Planck 2015 Temperature Power Spectra

“…The difference between cosmological constraints from WMAP and Planck TT spectra is driven by higher multipoles in Planck , which also drive the tensions with some astrophysical data discussed earlier. An important check of these Planck measurements will come from similar tests to those performed in this work using temperature and polarization measurements from high-resolution experiments (e.g., Louis et al 2014;Hou et al 2018).…”

Maps of the Southern Millimeter-wave Sky from Combined 2500 deg2 SPT-SZ and Planck Temperature Data

“…The three final maps are created with a resolution described by a Gaussian with FWHM of 1.85 arcmin, and individual sources measured to be brighter than 50 mJy at 150 GHz were masked from all three maps. The 150 GHz SPT-SZ map was calibrated to the Planck 143 GHz data in the SPT-SZ patch (Hou et al 2018). The 95 GHz and 220 GHz SPT-SZ data were calibrated by inter-comparison with the 150 GHz data.…”

“…We use this highly precise Planck calibration to calibrate the SPT-SZ maps. We use the 150 GHz calibration factor derived from comparison to Planck 143 GHz data in the SPT-SZ footprint from Hou et al (2018). We then inter-compare the SPT-SZ 95, 150, and 220 GHz maps to obtain calibration factors at 95 and 220 GHz.…”

Analytic Calculation of Covariance between Cosmological Parameters from Correlated Data Sets, with an Application to SPTpol

“…There are essentially two ways to assess the consistency of cosmological data sets: (1) comparing the data directly or (2) comparing the resulting parameter constraints. For CMB experiments, directly comparing the data can be done at either the map level (e.g., Louis et al 2014;Larson et al 2015;Hou et al 2018) or at the power spectrum level (e.g., Hou et al 2018;Huang et al 2018;Mocanu et al 2019). Changing the multipole moments included in the fit impacts the best-fit cosmology, and is a valuable internal consistency check (Addison et al 2016;Planck Collaboration LI 2017;Aylor et al 2017).…”