Vertical gradients of Galactic rotation from Gaia: The limiting-cone and comparison models
Year: 2026
Type: article
Abstract: Vertical variation of Galactic rotation constrains mass geometry beyond the mid-plane rotation curve, but Gaia measures stellar streaming, not the circular speed associated with the radial force. We distinguish the streaming, Jeans, and conditional mass-model declines ̊m S ), (G_ ̊m J ), and (G_ ̊m M ). For Gaia DR3 over (4łeq Rłeq8,̨pc) and (0łeq|Z|łeq2.4,̨pc), unrestricted-sample streaming estimates span (33)--(41, =40.910 =15.321 ) at (R_0=8.122,̨pc). There is therefore no universal vertical gradient: streaming is population-dependent, whereas a properly defined off-plane force decline can reduce the mass-distribution--rotation-curve degeneracy but is subject to explicit tracer, dynamical, weighting, and model assumptions. with (G_ ̊m S under the adopted common weight. A stationary axisymmetric Jeans reconstruction using one tracer weight for three means and six intrinsic covariances gives (G_ ̊m J the difference, (25.588 _ arises from second moments, radial pressure support, and velocity-ellipsoid tilt. Tracer density is the dominant quantified model systematic, giving approximately (10)--(21, =22.535) and (14.315, =1.107^ Conditional disk-only and disk-plus-sphere fields give (G_ ̊m M whereas finite near-azimuthal selections give (15.035)--(15.548, ) to (G_ ) within a fixed-shape family preserving the mid-plane curve gives (M_ /M_ despite different two-dimensional fields. Matching (G_ ̊m M ̊m J ̊m sphere ̊m disk +0.124 -0.112
Source: Astronomy and Astrophysics
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $1,865
OpenAlex ID: W7221667934