Redshift-Frame Systematics and Their Impact on the Hubble Constant from Pantheon+ Supernovae
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arXiv
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| Format: | Preprint |
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2025
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| _version_ | 1866912983372791808 |
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| author | Laaroua, Said |
| author_facet | Laaroua, Said |
| contents | We present a full-sky, covariance-weighted analysis of redshift-frame transformations in the Pantheon+ Type Ia supernova sample to assess their impact on local measurements of the Hubble constant. Using 1,543 supernovae with heliocentric and CMB-frame redshifts, we study the residual field delta z = zCMB - zHEL, which traces the Solar System's kinematic correction. We recover the expected monopole <delta z> = (-3.8 +/- 0.1) x 10^-4 and a dipole amplitude A = (1.5 +/- 0.1) x 10^-3 aligned within 1 degree of the CMB dipole, confirming internal consistency. Propagating these residuals through the full Pantheon+ covariance matrix yields a negligible shift in H0, at the <= 2% level of the current tension, placing a quantitative upper bound on redshift-frame systematics. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2511_06755 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Redshift-Frame Systematics and Their Impact on the Hubble Constant from Pantheon+ Supernovae Laaroua, Said Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies We present a full-sky, covariance-weighted analysis of redshift-frame transformations in the Pantheon+ Type Ia supernova sample to assess their impact on local measurements of the Hubble constant. Using 1,543 supernovae with heliocentric and CMB-frame redshifts, we study the residual field delta z = zCMB - zHEL, which traces the Solar System's kinematic correction. We recover the expected monopole <delta z> = (-3.8 +/- 0.1) x 10^-4 and a dipole amplitude A = (1.5 +/- 0.1) x 10^-3 aligned within 1 degree of the CMB dipole, confirming internal consistency. Propagating these residuals through the full Pantheon+ covariance matrix yields a negligible shift in H0, at the <= 2% level of the current tension, placing a quantitative upper bound on redshift-frame systematics. |
| title | Redshift-Frame Systematics and Their Impact on the Hubble Constant from Pantheon+ Supernovae |
| topic | Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2511.06755 |