Geometry-driven and dark-matter-sustained Milky Way rotation curves with Gaia DR3

Geometry-driven and dark-matter-sustained Milky Way rotation curves with Gaia DR3

2024 | William Beordo, Mariateresa Crosta, Mario G. Lattanzi, Paola Re Fiorentin, Alessandro Spagna
The paper presents a study of the Milky Way's rotation curve using Gaia DR3 data, comparing it with both classical and general relativistic (GR) models. The authors analyze 719,143 young disc stars within |z| < 1 kpc and up to R ≈ 19 kpc, providing high-quality astrometric and spectrophotometric data. They find that both the classical model with dark matter (DM) and the GR model based on a dust disc-scale metric can explain the observed rotational velocities with similar statistical quality. The GR model shows that the geometrical effect drives the velocity profile from 10 kpc outward, contributing ~30-37% of the profile at the Sun's distance, similar to the DM contribution in the classical model. This confirms the role of Einstein's geometry in explaining the flatness of the Milky Way rotation curve. The study also highlights the need for further investigation into the role of General Relativity in tracing the Milky Way rotation curve, as the origin of this gravitational dragging remains undetermined. The results suggest that the GR model can explain the observed rotation curve without requiring dark matter, with the 'gravitational dragging' effect playing a similar role to the DM halo in the classical model. The study uses Bayesian analysis to fit both models to the data, finding them statistically equivalent. The results confirm the validity of the GR approach and the importance of considering geometric effects in galactic dynamics. The paper also discusses the implications of these findings for our understanding of the Milky Way's structure and dynamics.The paper presents a study of the Milky Way's rotation curve using Gaia DR3 data, comparing it with both classical and general relativistic (GR) models. The authors analyze 719,143 young disc stars within |z| < 1 kpc and up to R ≈ 19 kpc, providing high-quality astrometric and spectrophotometric data. They find that both the classical model with dark matter (DM) and the GR model based on a dust disc-scale metric can explain the observed rotational velocities with similar statistical quality. The GR model shows that the geometrical effect drives the velocity profile from 10 kpc outward, contributing ~30-37% of the profile at the Sun's distance, similar to the DM contribution in the classical model. This confirms the role of Einstein's geometry in explaining the flatness of the Milky Way rotation curve. The study also highlights the need for further investigation into the role of General Relativity in tracing the Milky Way rotation curve, as the origin of this gravitational dragging remains undetermined. The results suggest that the GR model can explain the observed rotation curve without requiring dark matter, with the 'gravitational dragging' effect playing a similar role to the DM halo in the classical model. The study uses Bayesian analysis to fit both models to the data, finding them statistically equivalent. The results confirm the validity of the GR approach and the importance of considering geometric effects in galactic dynamics. The paper also discusses the implications of these findings for our understanding of the Milky Way's structure and dynamics.
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