Why is the distant-source count dipole larger than our motion predicts? · revision history
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- Title
- Why is the distant-source count dipole larger than our motion predicts?
- Plain
- Because the Earth moves relative to the cosmic microwave background, distant galaxies should look slightly more numerous in the direction of motion. Several catalogs show about twice the expected effect.
- Precise
- The CMB dipole implies a velocity of about $3.7e7\,\mathrm{cm/s}$, which predicts a kinematic number-count dipole (Ellis-Baldwin test) for distant sources. CatWISE2020 quasars and NVSS radio galaxies give amplitudes about twice the prediction, reported at about $5\sigma$ in joint analyses. Determine whether this signals a non-kinematic, intrinsic anisotropy incompatible with FLRW cosmology, or catalog systematics and clustering contributions.
- Settled by
- Number-count dipoles from independent deep surveys (Euclid, Rubin, SKA) with characterized selection functions, consistent or inconsistent with the kinematic value.
- Kind
- phenomenon
- Answer type
- identification
- References
- (empty)
- Literature status
- contested
- Status note
- 2025 to 2026 reanalyses including clustering and higher multipoles disagree on the significance.
- Posed since
- 1984