Abstract
ABSTRACT We examine the internal consistency of the Planck 2015 cosmic microwave background (CMB) temperature anisotropy power spectrum. We show that tension exists between cosmological constant cold dark matter ( Λ CDM ?> ) model parameters inferred from multipoles ℓ < 1000 ?> (roughly those accessible to Wilkinson Microwave Anisotropy Probe), and from ℓ ≥ 1000 ?> , particularly the CDM density, &OHgr; c h 2 ?> , which is discrepant at 2.5 &sgr; ?> for a Planck -motivated prior on the optical depth, τ = 0.07 ± 0.02 ?> . We find some parameter tensions to be larger than previously reported because of inaccuracy in the code used by the Planck Collaboration to generate model spectra. The Planck ℓ ≥ 1000 ?> constraints are also in tension with low-redshift data sets, including Planck ’s own measurement of the CMB lensing power spectrum ( 2.4 &sgr; ?> ), and the most precise baryon acoustic oscillation scale determination ( 2.5 &sgr; ?> ). The Hubble constant predicted by Planck from ℓ ≥ 1000 ?> , H 0 = 64.1 ± 1.7 ?> km s − 1 ?> Mpc−1, disagrees with the most precise local distance ladder measurement of 73.0 ± 2.4 ?> km s − 1 ?> Mpc−1 at the 3.0 &sgr; ?> level, while the Planck value from ℓ < 1000 ?> , 69.7 ± 1.7 ?> km s − 1 ?> Mpc−1, is consistent within 1 &sgr; ?> . A discrepancy between the Planck and South Pole Telescope high-multipole CMB spectra disfavors interpreting these tensions as evidence for new physics. We conclude that the parameters from the Planck high-multipole spectrum probably differ from the underlying values due to either an unlikely statistical fluctuation or unaccounted-for systematics persisting in the Planck data.
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