Galaxy Rotation Curves as Measurements of the CMB Spectral Index

2025/07/16 by Ferreira, Elisa G. M., L. Balkenhol, McDonough, Evan +7 · 32 citations
Earth and Planetary Sciences · Physics and Astronomy · #Cosmology and Gravitation Theories #Cosmology and Nongalactic Astrophysics (astro-ph.CO) #FOS: Physical sciences #General Relativity and Quantum Cosmology (gr-qc) #Geophysics and Gravity Measurements #High Energy Physics - Phenomenology (hep-ph) #High Energy Physics - Theory (hep-th)

paper · pdf · doi:10.48550/arxiv.2507.12459

openalex publication_date 2025/07/16 · openalex created_date 2025/10/10 · openalex updated_date 2026/07/28

Abstract

Letter (L1) of the Entropy-Response Gravity (Bipartite KMS Gravity) programme. The Bekenstein-Hawking entropy S=A/4G at the local Rindler-de Sitter horizon identifies the IR limit of the gravitational RG flow with the Wilson-Fisher fixed point of the large-N O(N) model. The fixed-point exponent beta'(g*)=-2 simultaneously fixes the asymptotic BTFR slope alpha=1/nu²=4 (SPARC selecting the underlying Standard interpolating function mu(x)=x/sqrt(1+x²) at 6.4 sigma across 173 galaxies) and the primordial scalar spectral index n_s = 1 - 2/N_e = 0.9741, with the dimensionless e-fold count N_e = 77.23 = ln(L_dS/l_P) - ln(T_P/T_eq). Tensor-to-scalar ratio r=0 exactly. Agrees with ACT DR6 at -0.06 sigma; +2.2 sigma from Planck 2018 (on the ACT side of the BAO-CMB tension). Falsifiers: r>0.001 at 5 sigma (CMB-S4/LiteBIRD) or |eta-1|>0.02 at 3 sigma (Euclid DR1). Version 7 note: the interpolating-function label is corrected to the Standard form (n=2) throughout (the n=2 formula was always printed; only the 'simple' label was wrong, a regression from v5/v6). The dimensionless n_s convention was already adopted in v6. No numerical results change. Pre-registered at OSF 10.17605/OSF.IO/8Z27K

Cited by

• Robustness of Starobinsky inflation in a minimal two-field scalar-tensor completion
• Exponential plateaus and inflation in metric-affine gravity
• Future Dark Energy Constraints from Atomic Clocks
• Dark Acoustic Oscillations as an Early-Universe Explanation of the DESI Anomaly
• Singular α-attractors
• Game Theory in Cosmology
• Fibre Inflation Meets Quintessence: Implications of Perturbative Stabilisation
• Dark Matter Freeze-in from a Z^′ Reheaton
• Symmetry-Protected α-Attractor Hybrid Inflation in Supergravity and Constraints from ACT DR6 and DESI DR2
• CMB observables and reheat temperature as a window to models of inflation and freeze-in dark matter production
• Higgs Inflation: Particle Factory
• GUT-Scale Smooth Hybrid Inflation with a Stabilized Modulus in Light of ACT and SPT Data
• The implications of inflation for the last ACT
• Cosmological Implications of Thermodynamic Split Conjecture
• Updating GUT-Scale Pole Higgs Inflation After ACT
• Effect of stochastic kicks on primordial black hole abundance and mass via the compaction function
• BaBy Cosmic Tension
• Aspects of non-minimally coupled curvature with power laws
• Beyond monomial α-attractors
• Unification of polynomial and exponential cosmological attractors
• Spectator Axions in String Inflation and Primordial Black Holes
• Inflation, Open Universes, and Dark Energy
• Thermodynamic Split Conjecture and an Observational Test for Cosmological Entropy
• Cosmic τensions Indirectly Correlate with Reionization Optical Depth
• Heavy Field Effects on Inflationary Models in Light of ACT Data
• Beyond the Starobinsky model after ACT
• The R²-Higgs inflation: R³ contribution and preheating after ACT and SPT data
• Observational challenges to holographic and Ricci dark energy paradigms: Insights from ACT DR6 and DESI DR2
• Alexei Starobinsky and Modern Cosmology
• Extra-natural production of superheavy Kaluza-Klein particles
• Inflation in F(R) gravity models revisited after ACT
• Viability of generalized α-inflation from Planck, ACT, and DESI Data

Related

• Inflation at the End of 2025: Constraints on r and n_s Using the Latest CMB and BAO Data
• The spectrum of n_s constraints from DESI and CMB data
• Impact of DESI BAO Data on Inflationary Parameters: stability against late-time new physics
• Constraints on Scalar Spectral Index from Latest Observational Measurements
• The Cosmological Effect of CMB/BAO Measurements