The Imprint of Spiral Arms on the Galactic Rotation Curve

McGaugh, Stacy S.

doi:10.3847/1538-4357/ab479b

Cited by 35 publications

(68 citation statements)

References 69 publications

(107 reference statements)

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“…Nearby, the rotation velocities are dominated by the known ridges in the (R, V * φ ) plane, which are now detected up to 14 kpc from the Galactic centre, that is 3 kpc farther than for DR2, while two additional ridges are discovered that reach 16-18 kpc. The overlap of distinct ridges in R seems to be the cause of some oscillation seen in the rotation curve, as already suggested by Martinez-Medina et al (2019), although they could also be related to the physical location of the spiral arms (Sancisi 2004;McGaugh 2019), rather than their resonances (Barros et al 2013).…”

Section: Discussion (I): Mw Disc Dynamicsmentioning

confidence: 53%

GaiaEarly Data Release 3

Antoja¹,

McMillan²,

Kordopatis³

et al. 2021

A&A

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Aims. We aim to demonstrate the scientific potential of the Gaia Early Data Release 3 (EDR3) for the study of different aspects of the Milky Way structure and evolution and we provide, at the same time, a description of several practical aspects of the data and examples of their usage. Methods. We used astrometric positions, proper motions, parallaxes, and photometry from EDR3 to select different populations and components and to calculate the distances and velocities in the direction of the anticentre. In this direction, the Gaia astrometric data alone enable the calculation of the vertical and azimuthal velocities; also, the extinction is relatively low compared to other directions in the Galactic plane. We then explore the disturbances of the current disc, the spatial and kinematical distributions of early accreted versus in situ stars, the structures in the outer parts of the disc, and the orbits of open clusters Berkeley 29 and Saurer 1. Results. With the improved astrometry and photometry of EDR3, we find that: (i) the dynamics of the Galactic disc are very complex with oscillations in the median rotation and vertical velocities as a function of radius, vertical asymmetries, and new correlations, including a bimodality with disc stars with large angular momentum moving vertically upwards from below the plane, and disc stars with slightly lower angular momentum moving preferentially downwards; (ii) we resolve the kinematic substructure (diagonal ridges) in the outer parts of the disc for the first time; (iii) the red sequence that has been associated with the proto-Galactic disc that was present at the time of the merger with Gaia-Enceladus-Sausage is currently radially concentrated up to around 14 kpc, while the blue sequence that has been associated with debris of the satellite extends beyond that; (iv) there are density structures in the outer disc, both above and below the plane, most probably related to Monoceros, the Anticentre Stream, and TriAnd, for which the Gaia data allow an exhaustive selection of candidate member stars and dynamical study; and (v) the open clusters Berkeley 29 and Saurer 1, despite being located at large distances from the Galactic centre, are on nearly circular disc-like orbits. Conclusions. Even with our simple preliminary exploration of the Gaia EDR3, we demonstrate how, once again, these data from the European Space Agency are crucial for our understanding of the different pieces of our Galaxy and their connection to its global structure and history.

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Section: Discussion (I): Mw Disc Dynamicsmentioning

confidence: 53%

GaiaEarly Data Release 3

Antoja¹,

McMillan²,

Kordopatis³

et al. 2021

A&A

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“…The OC memberships mostly come from Cantat-Gaudin & Anders (2020), who used the unsupervised classification scheme UPMASK (Krone-Martins & Moitinho 2014;Cantat-Gaudin et al 2018). These authors also applied UPMASK to the recently discovered University of Barcelona clusters (UBC, Castro-Ginard et al 2018, 2019 and to the clusters discovered by Liu & Pang (2019). For the Hyades and Coma Berenices, they adopted the list of members published by Gaia Collaboration (2018a) because UPMASK cannot recover members for populated clusters that are too extended on the sky.…”

Section: Input Datamentioning

confidence: 99%

“…A large fraction of candidate OCs could not be confirmed by Gaia or was proved to correspond to chance alignment. The number of OC candidates has also significantly increased, either through serendipitous discoveries in Gaia DR2 (Cantat-Gaudin et al 2018;Ferreira et al 2019), or as the result of systematic searches (Castro-Ginard et al 2018, 2019Cantat-Gaudin et al 2019;Sim et al 2019;Liu & Pang 2019). An updated catalogue of membership probabilities for 1481 OCs has been provided by .…”

Section: Introductionmentioning

confidence: 99%

3D kinematics and age distribution of the open cluster population

Tarricq

Soubiran

Casamiquela

et al. 2021

A&A

135

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Context. Open clusters (OCs) trace the evolution of the Galactic disc with great accuracy. Gaia and large ground-based spectroscopic surveys make it possible to determine their properties and study their kinematics with unprecedented precision. Aims. We study the kinematical behaviour of the OC population over time. We take advantage of the latest age determinations of OCs to investigate the correlations of the 6D phase-space coordinates and orbital properties with age. The phase-space distribution, age-velocity relation, and action distribution are compared to those of field stars. We also investigate the rotation curve of the Milky Way traced by OCs, and we compare it to that of other observational or theoretical studies. Methods. We gathered nearly 30 000 radial velocity (RV) measurements of OC members from both Gaia-RVS data and ground-based surveys and catalogues. We computed the weighted mean RV, Galactic velocities, and orbital parameters of 1382 OCs. We investigated their distributions as a function of age and by comparison to field stars. Results. We provide the largest RV catalogue available for OCs, half of it based on at least three members. Compared to field stars, we note that OCs are not on exactly the same arches in the radial-azimuthal velocity plane, while they seem to follow the same diagonal ridges in the Galactic radial distribution of azimuthal velocities. Velocity ellipsoids in different age bins all show a clear anisotropy. The heating rate of the OC population is similar to that of field stars for the radial and azimuthal components, but it is significantly lower for the vertical component. The rotation curve drawn by our sample of clusters shows several dips that match the wiggles derived from nonaxisymmetric models of the Galaxy. From the computation of orbits, we obtain a clear dependence of the maximum height and eccentricity on age. Finally, the orbital characteristics of the sample of clusters as shown by the action variables follow the distribution of field stars. The additional age information of the clusters indicates some (weak) age dependence of the known moving groups.

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“…15 In a recent paper [32] the same authors study the hypothesis of a condensate similar to the one of Bherezhiani/Khoury and formulate a model which, in its superfluid phase, leads ("in an idealized limit") to MOND-like dynamics again with the same interpolation function (73). They investigate whether such a model is consistent with empirical data from [38,44] on the rotation curve of the Milky Way. According to their analysis this is the case, if one allows a moderate rescaling of the baryonic mass by a factor f b = 0.8 which lies in the range of the observational uncertainty.…”

Section: A Short Look At Galactic Dynamicsmentioning

confidence: 90%

“…In the sequel we find a preference for setting β = 6 (see (38)) and reasons for assuming γ = 4 (Result b) on p. 20). So we can put the Lagrangians…”

Section: Lagrange Densitymentioning

confidence: 90%

A scalar field inducing a non-metrical contribution to gravitational acceleration and a compatible add-on to light deflection

Scholz¹

2020

Gen Relativ Gravit

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A scalar field model for explaining the anomalous acceleration and light deflection at galactic and cluster scales, without further dark matter, is presented. It is formulated in a scale covariant scalar tensor theory of gravity in the framework of integrable Weyl geometry and presupposes two different phases for the scalar field, like the superfluid approach of Berezhiani/Khoury. In low acceleration regimes of static gravitational fields (in the Einstein frame) with accordingly low values of the scalar field gradient, the scalar field Lagrangian combines a cubic kinetic term similar to the “a-quadratic” Lagrangian used in the first covariant generalization of MOND (RAQUAL) (Bekenstein and Milgrom in Astrophys J 286:7–14, 1984) and a second order derivative term introduced by Novello et al. in the context of a Weyl geometric approach to cosmology (Novello et al. in Int J Mod Phys D 1:641–677, 1993; de Oliveira et al. in Class Quantum Gravity 14(10):2833–2843, 1997). In varying with regard to $$\phi $$ ϕ the latter is variationally equivalent to a first order expression. The scalar field equation thus remains of order two. In the Einstein frame it assumes the form of a covariant generalization of the Milgrom equation known from the classical MOND approach in the deep MOND regime. It implies a corresponding “non-metrical” contribution to the acceleration of free fall trajectories. In contrast to pure RAQUAL, the second order derivative term of the Lagrangian leads to a non-negligible contribution to the energy momentum tensor and an add-on to the light deflection potential in beautiful agreement with the dynamics of low velocity trajectories. Although the model takes up important ingredients from the usual RAQUAL approach, it differs essentially from the latter.—In higher sectional curvature regions, respectively for higher accelerations in static fields, the scalar field Lagrangian consists of a Jordan–Brans–Dicke term with sufficiently high value of the JBD-constant to satisfy empirical constraints. Here the dynamics agrees effectively with the one of Einstein gravity.

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The Imprint of Spiral Arms on the Galactic Rotation Curve

Cited by 35 publications

References 69 publications

GaiaEarly Data Release 3

GaiaEarly Data Release 3

3D kinematics and age distribution of the open cluster population

A scalar field inducing a non-metrical contribution to gravitational acceleration and a compatible add-on to light deflection

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