The Radial Acceleration Relation (RAR): Crucial Cases of Dwarf Disks and Low-surface-brightness Galaxies

Paolo, Chiara Di; Salucci, Paolo; Fontaine, J. P.

doi:10.3847/1538-4357/aaffd6

Cited by 48 publications

(59 citation statements)

References 39 publications

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“…Similarly, we can see the appearance of a 0 in the RAR, between the observed centripetal acceleration derived from the rotation curve of disk galaxies and the Newtonian gravitational acceleration generated by the baryonic mass distribution (Figure 4): the deviation from the one-to-one relation appears at Newtonian accelerations smaller than a 0 and the relation is described by the interpolation function of Equation (19) [127]. Although the agreement shows no scatter and no dependence of the residuals on the galaxy properties [128,129], as expected for a relation driven by gravity alone, additional investigations are required to confirm these results, because some dependence of the residuals on the galaxy properties appears to be present in other galaxy samples different from SPARC [151,152].…”

Section: Disk Galaxiesmentioning

confidence: 72%

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Dark Matters on the Scale of Galaxies

et al. 2020

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The cold dark-matter model successfully explains both the emergence and evolution of cosmic structures on large scales and, when we include a cosmological constant, the properties of the homogeneous and isotropic Universe. However, the cold dark-matter model faces persistent challenges on the scales of galaxies. Indeed, N-body simulations predict some galaxy properties that are at odds with the observations. These discrepancies are primarily related to the dark-matter distribution in the innermost regions of the halos of galaxies and to the dynamical properties of dwarf galaxies. They may have three different origins: (1) the baryonic physics affecting galaxy formation is still poorly understood and it is thus not properly included in the model; (2) the actual properties of dark matter differs from those of the conventional cold dark matter; (3) the theory of gravity departs from General Relativity. Solving these discrepancies is a rapidly evolving research field. We illustrate some of the solutions proposed within the cold dark-matter model, and solutions when including warm dark matter, self-interacting dark matter, axion-like particles, or fuzzy dark matter. We also illustrate some modifications of the theory of gravity: Modified Newtonian Dynamics (MOND), MOdified Gravity (MOG), and f(R) gravity.

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Section: Disk Galaxiesmentioning

confidence: 72%

“…An additional unsettled controversy is the correlation between the residuals of the observed rotation curves from relation (4) and the properties of the galaxies observed in galaxy samples [151,152] different from SPARC, where this correlation appears to be absent [130].…”

Section: Observational Evidencementioning

confidence: 99%

Dark Matters on the Scale of Galaxies

et al. 2020

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“…researchers as extreme examples that might show eccentric behaviour (e.g., Oman et al 2016;van Dokkum et al 2018;Guo et al 2019), as well as those who attempt to extend the RAR to lower accelerations using galaxy rotation curves (Lelli et al 2017b;Di Paolo et al 2019). We therefore select a sample of dwarfs: isolated galaxies with a stellar mass M < 10 10 h −2 70 M (whereas the full sample of isolated galaxies has M < 10 11 h −2 70 M , see Sect.…”

Section: The Rar Of Low-mass (Dwarf) Late-type Galaxiesmentioning

confidence: 99%

The weak lensing radial acceleration relation: Constraining modified gravity and cold dark matter theories with KiDS-1000

Brouwer

Oman²,

Valentijn³

et al. 2021

A&A

130

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We present measurements of the radial gravitational acceleration around isolated galaxies, comparing the expected gravitational acceleration given the baryonic matter (gbar) with the observed gravitational acceleration (gobs), using weak lensing measurements from the fourth data release of the Kilo-Degree Survey (KiDS-1000). These measurements extend the radial acceleration relation (RAR), traditionally measured using galaxy rotation curves, by 2 decades in gobs into the low-acceleration regime beyond the outskirts of the observable galaxy. We compare our RAR measurements to the predictions of two modified gravity (MG) theories: modified Newtonian dynamics and Verlinde’s emergent gravity (EG). We find that the measured relation between gobs and gbar agrees well with the MG predictions. In addition, we find a difference of at least 6σ between the RARs of early- and late-type galaxies (split by Sérsic index and u − r colour) with the same stellar mass. Current MG theories involve a gravity modification that is independent of other galaxy properties, which would be unable to explain this behaviour, although the EG theory is still limited to spherically symmetric static mass models. The difference might be explained if only the early-type galaxies have significant (Mgas ≈ M⋆) circumgalactic gaseous haloes. The observed behaviour is also expected in Λ-cold dark matter (ΛCDM) models where the galaxy-to-halo mass relation depends on the galaxy formation history. We find that MICE, a ΛCDM simulation with hybrid halo occupation distribution modelling and abundance matching, reproduces the observed RAR but significantly differs from BAHAMAS, a hydrodynamical cosmological galaxy formation simulation. Our results are sensitive to the amount of circumgalactic gas; current observational constraints indicate that the resulting corrections are likely moderate. Measurements of the lensing RAR with future cosmological surveys (such as Euclid) will be able to further distinguish between MG and ΛCDM models if systematic uncertainties in the baryonic mass distribution around galaxies are reduced.

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“…In particular, the impact of the pressure gradient force analogous to a frictionless rotating system like twisters may play an important role in galactic motion in the universe. The cyclostrophic model for vortices such as tornadoes occurring in nature is a simple balance between the inward pressure gradient force and the outward centrifugal force [1]. In the absence of Coriolis effect and negligible friction, tornadoes were observed to obey this basic rule.…”

Section: Methods and Theorymentioning

confidence: 99%

An Alternative Model of Rotation Curve that Explains Anomalous Orbital Velocity, Mass Discrepancy and Structure of Some Galaxies

Rivera¹,

Rivera²

2019

AJAA

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A new model of galaxy rotation based on the cyclostrophic model of vortices found in nature is developed. The model is tested using the SPARC dataset of 175 galaxies and a smaller dataset comprising of 60 galaxies. Analysis of the datasets showed that galactic rotation can be adequately described using the observed surface brightness of galaxies and the newly developed cyclostrophic velocity model. The use of the luminosity and the inverse mass-to-light ratio in lieu of the surface brightness, also yield a very good fit of the observed and computed galaxy rotation velocity. Evidently, galactic rotation greatly depends on the cyclostrophic balance of the pressure gradient and the centrifugal forces and the seismic-induced radial expansion occurring in various stars. This is the most probable origin of the action of a single force law that has been overlooked in previous studies. Therefore, the need for a super-massive black hole at the center of galaxies or hidden dark matter can be eliminated. Attractive gravitational force can occur even without a massive black hole at the center of galaxies. There appears to be a pressure gradient force between the center and the outer parts of galaxies that sustains attraction. The cyclostrophic model appears to be the physical basis of the Tully-Fisher relation. Furthermore, the missing mass problem associated with galactic rotation can be attributed to the orbital expansion of celestial objects perturbed by seismic-induced forces. In addition, massive tremors or starquakes may create a domino effect in perturbing nearby stars along the axis of the seismic-induced force and this could result in the formation of elliptical galaxies as the orbits of seismic-perturbed neighboring stars become larger.

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The Radial Acceleration Relation (RAR): Crucial Cases of Dwarf Disks and Low-surface-brightness Galaxies

Cited by 48 publications

References 39 publications

Dark Matters on the Scale of Galaxies

Dark Matters on the Scale of Galaxies

The weak lensing radial acceleration relation: Constraining modified gravity and cold dark matter theories with KiDS-1000

An Alternative Model of Rotation Curve that Explains Anomalous Orbital Velocity, Mass Discrepancy and Structure of Some Galaxies

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