Nearly Full-Sky Low-Multipole CMB Temperature Anisotropy: II. Angular Power Spectra and Likelihood
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arXiv
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| Auteurs principaux: | , , , , |
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| Format: | Preprint |
| Publié: |
2025
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| _version_ | 1866911137172291584 |
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| author | Nofi, Hayley C. Addison, Graeme E. Bennett, Charles L. Herold, Laura Weiland, J. L. |
| author_facet | Nofi, Hayley C. Addison, Graeme E. Bennett, Charles L. Herold, Laura Weiland, J. L. |
| contents | We present a CMB temperature power spectrum measurement at large angular scales from WMAP and Planck maps that were cleaned of foregrounds using a template-based approach described in a companion paper. We recover essentially the full-sky CMB information at multipoles $\ell<30$ with only 1% of pixels near the Galactic plane masked and no inpainting. Notable features continue to appear: (a) a low quadrupole power compared to the best-fit Planck 2018 $Λ$CDM spectrum at $2.2σ$, (b) a dip in the range $20 \le \ell \le 27$, and (c) an overall $\ell<30$ power level low of the $Λ$CDM prediction derived from higher multipole moments. Given the different methodology from previous analyses and the nearly full-sky solution presented here, these features do not plausibly arise from foreground contamination, systematic errors, masking, or mode-mixing. Our overall $\ell<30$ amplitude constraint is consistent with published WMAP (77% sky fraction) and Planck (86%) results at $1.2σ$ and $0.6σ$, respectively, accounting for the improvement in statistical precision. We present a new $\ell<30$ likelihood for use with the Cobaya package. Parameter constraints from joint fits with the higher-multipole Planck data are consistent with the published Planck results, for example we find $H_0=67.35\pm0.54$ km s$^{-1}$ Mpc$^{-1}$ in a joint $Λ$CDM fit. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_03719 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Nearly Full-Sky Low-Multipole CMB Temperature Anisotropy: II. Angular Power Spectra and Likelihood Nofi, Hayley C. Addison, Graeme E. Bennett, Charles L. Herold, Laura Weiland, J. L. Cosmology and Nongalactic Astrophysics We present a CMB temperature power spectrum measurement at large angular scales from WMAP and Planck maps that were cleaned of foregrounds using a template-based approach described in a companion paper. We recover essentially the full-sky CMB information at multipoles $\ell<30$ with only 1% of pixels near the Galactic plane masked and no inpainting. Notable features continue to appear: (a) a low quadrupole power compared to the best-fit Planck 2018 $Λ$CDM spectrum at $2.2σ$, (b) a dip in the range $20 \le \ell \le 27$, and (c) an overall $\ell<30$ power level low of the $Λ$CDM prediction derived from higher multipole moments. Given the different methodology from previous analyses and the nearly full-sky solution presented here, these features do not plausibly arise from foreground contamination, systematic errors, masking, or mode-mixing. Our overall $\ell<30$ amplitude constraint is consistent with published WMAP (77% sky fraction) and Planck (86%) results at $1.2σ$ and $0.6σ$, respectively, accounting for the improvement in statistical precision. We present a new $\ell<30$ likelihood for use with the Cobaya package. Parameter constraints from joint fits with the higher-multipole Planck data are consistent with the published Planck results, for example we find $H_0=67.35\pm0.54$ km s$^{-1}$ Mpc$^{-1}$ in a joint $Λ$CDM fit. |
| title | Nearly Full-Sky Low-Multipole CMB Temperature Anisotropy: II. Angular Power Spectra and Likelihood |
| topic | Cosmology and Nongalactic Astrophysics |
| url | https://arxiv.org/abs/2509.03719 |