Turning Galaxy Rotation Curves into Radial Cosmic Chronometers: A Nexus Paradigm Approach
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| Format: | Preprint |
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2026
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| author | Marongwe, Stuart Kauffman, Stuart A. |
| author_facet | Marongwe, Stuart Kauffman, Stuart A. |
| contents | We present a method for transforming galaxy rotation curves into radially resolved dynamical chronometers, enabling reconstruction of galaxy assembly histories directly from kinematic data. Within the Nexus Paradigm, the baryonic Tully-Fisher relation provides an estimate of the dynamical mass profile $ M_{dyn}(r)=v^4/Ga_0$, where $a_0=H_0/2π$.By Comparing this with independently derived intrinsic baryonic mass profiles, $M_{int}(r)$, obtained from stellar Sérsic fits and gas surface density measurements, we construct the ratio $ M_{dyn}(r)/M_{int}(r)$, which maps directly to a formation redshift via $ 1+z_{form}(r)=(M_{dyn}/M_{int})^{1/4}$. Inverting this relation with$ΛCDM$ cosmology yields a radial lookback-time profile, $t_{lb}(r)$, representing the time since the last dynamical reconfiguration at each radius. Applying this framework to a pilot sample of SPARC galaxies spanning high-and low -surface-brightness systems, together with the Milky Way, we recover diverse radial age structures, including flat profiles consistent with coherent disk assembly and stratified profiles indicative of inside-out growth. The method operates without dark-matter halo fitting and provides a kinematic chronometer complementary to stellar-population and chemical-evolution approaches. While the inferred ages depend on the accuracy of baryonic mass reconstruction and local applicability of the evolving baryonic Tully-Fisher relation, the results demonstrate that galaxy rotation curves encode time-resolved dynamical information. This establishes the radial dynamical chronometer as a new observable for probing galaxy evolution and testing gravitational frameworks. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2604_17597 |
| institution | arXiv |
| publishDate | 2026 |
| record_format | arxiv |
| spellingShingle | Turning Galaxy Rotation Curves into Radial Cosmic Chronometers: A Nexus Paradigm Approach Marongwe, Stuart Kauffman, Stuart A. Astrophysics of Galaxies We present a method for transforming galaxy rotation curves into radially resolved dynamical chronometers, enabling reconstruction of galaxy assembly histories directly from kinematic data. Within the Nexus Paradigm, the baryonic Tully-Fisher relation provides an estimate of the dynamical mass profile $ M_{dyn}(r)=v^4/Ga_0$, where $a_0=H_0/2π$.By Comparing this with independently derived intrinsic baryonic mass profiles, $M_{int}(r)$, obtained from stellar Sérsic fits and gas surface density measurements, we construct the ratio $ M_{dyn}(r)/M_{int}(r)$, which maps directly to a formation redshift via $ 1+z_{form}(r)=(M_{dyn}/M_{int})^{1/4}$. Inverting this relation with$ΛCDM$ cosmology yields a radial lookback-time profile, $t_{lb}(r)$, representing the time since the last dynamical reconfiguration at each radius. Applying this framework to a pilot sample of SPARC galaxies spanning high-and low -surface-brightness systems, together with the Milky Way, we recover diverse radial age structures, including flat profiles consistent with coherent disk assembly and stratified profiles indicative of inside-out growth. The method operates without dark-matter halo fitting and provides a kinematic chronometer complementary to stellar-population and chemical-evolution approaches. While the inferred ages depend on the accuracy of baryonic mass reconstruction and local applicability of the evolving baryonic Tully-Fisher relation, the results demonstrate that galaxy rotation curves encode time-resolved dynamical information. This establishes the radial dynamical chronometer as a new observable for probing galaxy evolution and testing gravitational frameworks. |
| title | Turning Galaxy Rotation Curves into Radial Cosmic Chronometers: A Nexus Paradigm Approach |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2604.17597 |