Monthly Notices of the Royal Astronomical Society
G. T. Alcock · Vol. 551, Issue 4 · stag1485 · doi:10.1093/mnras/stag1485
Is the acceleration scale of the radial acceleration relation tracking the cosmic expansion rate?
The MUSE-DARK survey reported that the acceleration scale a0 of the radial acceleration relation rises strongly with redshift over 0.33 < z < 1.44. This paper confronts the same binned measurements with physically motivated scalings, using a0(z) = A (1+z)γ as the primary statistic.
With the published bin errors read as 1σ, a fixed scale is excluded at 5.3σ and matter-density scaling at 4.8σ. Hubble tracking, a0 ∝ H(z), is consistent within 2.1σ and is the information-criterion-preferred one-parameter description. The long-noted coincidence a0 ~ cH0 survives its first confrontation with direct kinematic measurements at intermediate redshift.
The analysis is model-independent. It does not assume Density Field Dynamics, which is a separate research program whose papers are preprints.
Alcock, G. T. (2026). Is the acceleration scale of the radial acceleration relation tracking the cosmic expansion rate? Monthly Notices of the Royal Astronomical Society, 551(4), stag1485. https://doi.org/10.1093/mnras/stag1485
@article{Alcock2026,
author = {Alcock, G. T.},
title = {Is the acceleration scale of the radial acceleration relation tracking the cosmic expansion rate?},
journal = {Monthly Notices of the Royal Astronomical Society},
year = {2026},
volume = {551},
number = {4},
pages = {stag1485},
doi = {10.1093/mnras/stag1485}
}
MUSE-DARK bins compared with three scalings. Model amplitudes are fitted to the four bins.
- MUSE-DARK bins
- SPARC, today
- a0 ∝ H(z)
- Constant a0
- a0 ∝ (1+z)1.5
Data table
| Sample | z | a0 | Error |
|---|---|---|---|
| SPARC (local) | 0 | 1.20 | ±0.02 stat, ±0.24 sys |
| MUSE-DARK bin 1 | 0.503 | 1.990 | −0.085 / +0.086 |
| MUSE-DARK bin 2 | 0.825 | 2.200 | ±0.105 |
| MUSE-DARK bin 3 | 1.047 | 2.571 | −0.114 / +0.110 |
| MUSE-DARK bin 4 | 1.276 | 2.710 | −0.134 / +0.138 |
Units of 10−10 m s−2. Bins from Ciocan et al. (2026) as analysed in the paper; SPARC value from McGaugh, Lelli & Schombert (2016).