Modified Gravity and the Origin of the Excess Radio Galaxy Number-Count Dipole
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arXiv
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| Format: | Preprint |
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2026
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| _version_ | 1866912818201100288 |
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| author | Moffat, John. W. |
| author_facet | Moffat, John. W. |
| contents | Recent analyses of wide-area radio-galaxy surveys have reported a statistically significant excess in the cosmic number-count dipole, with an amplitude exceeding the purely kinematic expectation of the standard $Λ$CDM model by a factor of $\sim 3$--$4$, quoted at a significance level of up to $5.4σ$. While residual observational systematics and local-structure effects cannot be definitively excluded, this result motivates the exploration of alternative physical interpretations beyond the minimal $Λ$CDM framework. We investigate whether Scalar--Tensor--Vector Gravity (STVG-MOG) can provide a consistent explanation for an enhanced large-scale anisotropic dipole without violating existing constraints from early-universe cosmology, the cosmic microwave background (CMB) dipole, galaxy dynamics, weak lensing, or the observed late-time matter power spectrum. The radio number-count dipole probes ultra-large-scale, anisotropic structure and coherent gravitational response, rather than virialized dynamics or linear growth alone. In STVG-MOG, a scale- and time-dependent effective gravitational coupling preserves standard cosmological evolution at early times and on small to intermediate scales, while amplifying gravitational response on gigaparsec scales. This scale-selective enhancement can increase the large-scale structure contribution to the radio dipole without overproducing power on smaller scales. If the observed dipole excess reflects a physical cosmological signal rather than residual systematics, STVG-MOG offers a viable and testable alternative interpretation. It is demonstrated that the radio dipole anomaly provides a novel probe of gravitational physics on the largest observable scales. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2601_07487 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Modified Gravity and the Origin of the Excess Radio Galaxy Number-Count Dipole Moffat, John. W. Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies General Relativity and Quantum Cosmology Recent analyses of wide-area radio-galaxy surveys have reported a statistically significant excess in the cosmic number-count dipole, with an amplitude exceeding the purely kinematic expectation of the standard $Λ$CDM model by a factor of $\sim 3$--$4$, quoted at a significance level of up to $5.4σ$. While residual observational systematics and local-structure effects cannot be definitively excluded, this result motivates the exploration of alternative physical interpretations beyond the minimal $Λ$CDM framework. We investigate whether Scalar--Tensor--Vector Gravity (STVG-MOG) can provide a consistent explanation for an enhanced large-scale anisotropic dipole without violating existing constraints from early-universe cosmology, the cosmic microwave background (CMB) dipole, galaxy dynamics, weak lensing, or the observed late-time matter power spectrum. The radio number-count dipole probes ultra-large-scale, anisotropic structure and coherent gravitational response, rather than virialized dynamics or linear growth alone. In STVG-MOG, a scale- and time-dependent effective gravitational coupling preserves standard cosmological evolution at early times and on small to intermediate scales, while amplifying gravitational response on gigaparsec scales. This scale-selective enhancement can increase the large-scale structure contribution to the radio dipole without overproducing power on smaller scales. If the observed dipole excess reflects a physical cosmological signal rather than residual systematics, STVG-MOG offers a viable and testable alternative interpretation. It is demonstrated that the radio dipole anomaly provides a novel probe of gravitational physics on the largest observable scales. |
| title | Modified Gravity and the Origin of the Excess Radio Galaxy Number-Count Dipole |
| topic | Cosmology and Nongalactic Astrophysics Astrophysics of Galaxies General Relativity and Quantum Cosmology |
| url | https://arxiv.org/abs/2601.07487 |