The more complex dark matter particle mass models of the Milky Way, perform not better in describing what we see with other telescopes than the far simply MOND model when it comes to the Milky Way's rotation curve.
We use data from the Gaia DR3 dataset to estimate the mass of the Milky Way (MW) by analyzing the rotation curve in the range of distances 5 kpc to 28 kpc.
We consider three mass models: the first model adds a spherical dark matter (DM) halo, following the Navarro-Frenk-White (NFW) profile, to the known stellar components. The second model assumes that DM is confined to the Galactic disk, following the idea that the observed density of gas in the Galaxy is related to the presence of more massive DM disk (DMD), similar to the observed correlation between DM and gas in other galaxies. The third model only uses the known stellar mass components and is based on the Modified Newton Dynamics (MOND) theory.
Our results indicate that the DMD model is comparable in accuracy to the NFW and MOND models and fits the data better at large radii where the rotation curve declines but has the largest errors. For the NFW model we obtain a virial mass M(vir)=(6.5±0.3)×10^11M⊙ with concentration parameter c=14.5, that is lower than what is typically reported. In the DMD case we find that the MW mass is M(d)=(1.6±0.5)×10^11M⊙ with a disk's characteristic radius of Rd=17 kpc.
Francesco Sylos Labini, et al., "Mass models of the Milky Way and estimation of its mass from the GAIA DR3 data-set" arXiv:2302.01379 (February 2, 2023) (accepted for publication in The Astrophysical Journal).
4 comments:
a newer take
with Refracted Gravity, a novel classical theory of gravity introduced in 2016, where the modification of the law of gravity is instead regulated by a density scale.
Dark Coincidences: Small-Scale Solutions with Refracted Gravity and MOND
Valentina Cesare
General relativity and its Newtonian weak field limit are not sufficient to explain the observed phenomenology in the Universe, from the formation of large-scale structures to the dynamics of galaxies, with the only presence of baryonic matter. The most investigated cosmological model, the ΛCDM, accounts for the majority of observations by introducing two dark components, dark energy and dark matter, which represent ∼95% of the mass-energy budget of the Universe. Nevertheless, the ΛCDM model faces important challenges on the scale of galaxies. For example, some very tight relations between the properties of dark and baryonic matters in disk galaxies, such as the baryonic Tully-Fisher relation (BTFR), the mass discrepancy-acceleration relation (MDAR), and the radial acceleration relation (RAR), which see the emergence of the acceleration scale a0≃1.2×10−10 m s−2, cannot be intuitively explained by the CDM paradigm, where cosmic structures form through a stochastic merging process. An even more outstanding coincidence is due to the fact that the acceleration scale a0, emerging from galaxy dynamics, also seems to be related to the cosmological constant Λ. Another challenge is provided by dwarf galaxies, which are darker than what is expected in their innermost regions. These pieces of evidence can be more naturally explained, or sometimes even predicted, by modified theories of gravity, that do not introduce any dark fluid. I illustrate possible solutions to these problems with the modified theory of gravity MOND, which departs from Newtonian gravity for accelerations smaller than a0, and with Refracted Gravity, a novel classical theory of gravity introduced in 2016, where the modification of the law of gravity is instead regulated by a density scale.
Comments: 34 pages, 7 figures, published on 16th January 2023 in Universe 2023, 9(1), 56, in the Special Issue "Modified Gravity and Dark Matter at the Scale of Galaxies"; accepted for publication on 12th January 2023
Subjects: Astrophysics of Galaxies (astro-ph.GA)
Cite as: arXiv:2301.07115 [astro-ph.GA]
(or arXiv:2301.07115v1 [astro-ph.GA] for this version)
refracted gravity has been more researchers than Deur
Covariant Formulation of refracted gravity
Andrea Pierfrancesco Sanna, Titos Matsakos, Antonaldo Diaferio
We propose a covariant formulation of refracted gravity (RG), a classical theory of gravity based on the introduction of the gravitational permittivity -- a monotonic function of the local mass density -- in the standard Poisson equation. The gravitational permittivity mimics the dark matter phenomenology. Our covariant formulation of RG (CRG) belongs to the class of scalar-tensor theories, where the scalar field φ has a self-interaction potential V(φ)=−Ξφ, with Ξ a normalization constant. We show that the scalar field is twice the gravitational permittivity in the weak-field limit. Far from a spherical source of density ρs(r), the transition between the Newtonian and the RG regime appears below the acceleration scale aΞ=(2Ξ−8πGρ/φ)1/2, with ρ=ρs+ρbg and ρbg an isotropic and homogeneous background. In the limit 2Ξ≫8πGρ/φ, we obtain aΞ∼10−10~m~s−2. This acceleration is comparable to the acceleration a0 originally introduced in Modified Newtonian Dynamics (MOND). From CRG, we also derive the modified Friedmann equations for an expanding, homogeneous, and isotropic universe. We find that the same scalar field that mimics dark matter also drives the accelerated expansion of the Universe. Since Ξ plays a role roughly similar to the cosmological constant Λ in the standard model and has a comparable value, CRG suggests a natural explanation of the known relation a0∼Λ1/2. CRG thus appears to describe both the dynamics of cosmic structure and the expanding Universe with a single scalar field, and falls within the family of models that unify the two dark sectors, highlighting a possible deep connection between phenomena currently attributed to dark matter and dark energy separately.
Comments: 16 pages, 1 figure, small change in the title, submitted to Physical Review D
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
Cite as: arXiv:2109.11217 [astro-ph.CO]
@neo
Thanks for the heads up. I'll take a look when I have a chance.
Collectively, all theories that propose a gravitational or modified gravitational explanation for dark matter phenomena are strongly preferred in my view.
This is first, because any explanation has to be consistent with the explanatory and predictive power of MOND where it works, and second, because so much of the dark matter particle theory parameter space has been ruled out by the recent torrent of new astronomy data, direct dark matter detection search data, and collider data.
i thought you would
has been more cited than Deur
based on Tuesday simple ideas in analogy to EM
a classical theory of gravity based on the introduction of the gravitational permittivity
Our covariant formulation of RG (CRG) belongs to the class of scalar-tensor theories, where the scalar field φ has a self-interaction potential V(φ)=−Ξφ, with Ξ a normalization constant. We show that the scalar field is twice the gravitational permittivity in the weak-field limit. Far from a spherical source of density ρs(r), the transition between the Newtonian and the RG regime appears below the acceleration scale aΞ=(2Ξ−8πGρ/φ)1/2, with ρ=ρs+ρbg and ρbg an isotropic and homogeneous background. In the limit 2Ξ≫8πGρ/φ, we obtain aΞ∼10−10~m~s−2. This acceleration is comparable to the acceleration a0 originally introduced in Modified Newtonian Dynamics (MOND).
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