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Anisotropic Distance Ladder in Pantheon+ Supernovae

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arxiv 2304.02718 v2 pith:SRH475A7 submitted 2023-04-05 astro-ph.CO gr-qchep-phhep-th

Anisotropic Distance Ladder in Pantheon+ Supernovae

classification astro-ph.CO gr-qchep-phhep-th
keywords variationshubbleanisotropiccepheidconstantdistanceladderpantheon
verification ladder T0 review T1 audit T2 compute T3 formal T4 reserved
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We decompose Pantheon+ Type Ia supernovae (SN) in hemispheres on the sky finding angular variations up to $4$ km/s/Mpc in the Hubble constant $H_0$ both in the SH0ES redshift range $0.0233 < z < 0.15$ and in extended redshift ranges. The variations are driven largely by variations in absolute magnitude from SN in Cepheid hosts, but are reinforced by SN in the Hubble flow. $H_0$ is larger in a hemisphere encompassing the CMB dipole direction. The variations we see exceed the errors on the recent SH0ES determination, $H_0 = 73.04 \pm 1.04$ km/s/Mpc, but are not large enough to explain early versus late Universe discrepancies in the Hubble constant. Nevertheless, the Cepheid-SN distance ladder is anisotropic at current precision. The anisotropy may be due to a breakdown in the Cosmological Principle, or mundanely due to a statistical fluctuation in a small sample of SN in Cepheid host galaxies.

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Cited by 4 Pith papers

Reviewed papers in the Pith corpus that reference this work. Sorted by Pith novelty score.

  1. Multipolar structure of the local expansion rate from incomplete sky data

    astro-ph.CO 2026-07 conditional novelty 6.0

    CF4 data yield a 3.3σ excess dipole in the local expansion-rate fluctuation field at (l,b)=(290°,-4°)±5°, sourced mainly by z∈[0.03,0.05], with quadrupole/octupole consistent with ΛCDM and no multipole-vector alignments.

  2. New constraints on cosmic anisotropy from galaxy clusters using an improved dipole fitting method

    astro-ph.CO 2026-02 unverdicted novelty 5.0

    Galaxy cluster observations yield two preferred directions with cosmic anisotropy amplitude of about 5.3 times 10 to the minus 4 at roughly 1 sigma overall significance, though higher in the XMM-Newton subsample.

  3. Probing cosmic anisotropy with galaxy clusters and supernovae

    astro-ph.CO 2026-04 unverdicted novelty 4.0

    Analysis of galaxy cluster and supernova data reveals a ~2σ directional variation in the Hubble constant, robust across calibration methods and aligned with the CMB dipole.

  4. Updates on dipolar anisotropy in local measurements of the Hubble constant from Cosmicflows-4

    astro-ph.CO 2025-12 unverdicted novelty 4.0

    Local Hubble constant anisotropy in Cosmicflows-4 data is primarily attributed to peculiar velocities and survey structure rather than cosmic-scale isotropy violation, with limited implications for the Hubble tension.