Quantifying discordance in the 2015 Planck CMB spectrum
- Dept. of Physics and Astronomy, The John Hopkins University, 3400 N. Charles St., Baltimore, MD 21218-2686 (United States)
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 (ΛCDM) model parameters inferred from multipoles ℓ<1000 (roughly those accessible to Wilkinson Microwave Anisotropy Probe), and from ℓ⩾1000, particularly the CDM density, Ω{sub c}h{sup 2}, which is discrepant at 2.5σ 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 (2.4σ), and the most precise baryon acoustic oscillation scale determination (2.5σ). The Hubble constant predicted by Planck from ℓ⩾1000, H{sub 0}=64.1±1.7 km s{sup −1} Mpc{sup −1}, disagrees with the most precise local distance ladder measurement of 73.0±2.4 km s{sup −1} Mpc{sup −1} at the 3.0σ level, while the Planck value from ℓ<1000, 69.7±1.7 km s{sup −1} Mpc{sup −1}, is consistent within 1σ. 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.
- OSTI ID:
- 22887019
- Journal Information:
- Astrophysical Journal, Vol. 818, Issue 2; Other Information: Country of input: International Atomic Energy Agency (IAEA); Since 2009, the country of publication for this journal is the UK.; ISSN 0004-637X
- Country of Publication:
- United Kingdom
- Language:
- English
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