Age-Resolved Vertical Motions in the Milky Way Warp: A Localized Enhancement in Intermediate-Age Populations
Abstract
Determining how the Milky Way warp evolves provides constraints on the formation and dynamical evolution of galactic disks. Using Apache Point Observatory Galactic Evolution Experiment Data Release 19 (APOGEE DR19) spectroscopy, we estimate ages for 222,355 red giants. With Gaia astrometry and geometric distances, we analyze 168,824 of these stars in five age bins spanning $0−−10$ Gyr. The warp-related radial vertical-velocity (VZ) profile of young red giants ($0−−2$ Gyr) is broadly consistent with those of classical Cepheids and young open clusters. Over 9≤ R<12 kpc, we find that the mean VZ values of the intermediate-age red giants ($2−−4$ and $4−−6$ Gyr) are 1.48±0.46 and 1.49±0.52 km s−1 higher than that of the young population, respectively. By contrast, at R≃12--$13$ kpc, the VZ profiles of the $0−−6$ Gyr red giants are consistent within their uncertainties. The intermediate-age enhancement persists across our robustness tests and may reflect smaller effective kinematic warp onset radii for the intermediate-age populations. The observed velocity differences may arise from the combined effects of earlier perturbations and the present-day warp, or from differences in vertical structure among stellar populations.
Related
- Resolved Structure and Orbital Motion of a Localized 1 au-scale Dust Accumulation in the Protoplanetary Disk around TW Hya
- The Stellar Populations of Resolved Galaxies
- Mock CSST NUV-NIR imaging of TNG50 galaxies with resolved stellar populations
- Vertical gradients of Galactic rotation from Gaia: The limiting-cone and comparison models
- Dust-driven vertical shear instability in an isothermal shearing box. I. Turbulence and gas dynamics without dust feedback
BibTeX
@misc{zhou2026ageresolved,
title = {{Age-Resolved Vertical Motions in the Milky Way Warp: A Localized Enhancement in Intermediate-Age Populations}},
author = {Xiaoyue Zhou and Xiaodian Chen and Haifeng Wang and Shu Wang and Zhihong He and Licai Deng},
howpublished = {arXiv},
year = {2026},
month = oct,
doi = {10.48550/arxiv.2610.38235},
eprint = {2610.38235},
archivePrefix = {arXiv},
url = {https://arxiv.org/abs/2610.38235},
note = {CC BY 4.0},
}
RIS
TY - UNPB
TI - Age-Resolved Vertical Motions in the Milky Way Warp: A Localized Enhancement in Intermediate-Age Populations
AU - Xiaoyue Zhou
AU - Xiaodian Chen
AU - Haifeng Wang
AU - Shu Wang
AU - Zhihong He
AU - Licai Deng
PY - 2026
DA - 2026/10/28
PB - arXiv
DO - 10.48550/arxiv.2610.38235
UR - https://arxiv.org/abs/2610.38235
AB - Determining how the Milky Way warp evolves provides constraints on the formation and dynamical evolution of galactic disks. Using Apache Point Observatory Galactic Evolution Experiment Data Release 19 (APOGEE DR19) spectroscopy, we estimate ages for 222,355 red giants. With Gaia astrometry and geometric distances, we analyze 168,824 of these stars in five age bins spanning $0−−10$ Gyr. The warp-related radial vertical-velocity (V_Z) profile of young red giants ($0−−2$ Gyr) is broadly consistent with those of classical Cepheids and young open clusters. Over 9≤ R<12 kpc, we find that the mean V_Z values of the intermediate-age red giants ($2−−4$ and $4−−6$ Gyr) are 1.48±0.46 and 1.49±0.52 km s^−1 higher than that of the young population, respectively. By contrast, at R≃12--$13$ kpc, the V_Z profiles of the $0−−6$ Gyr red giants are consistent within their uncertainties. The intermediate-age enhancement persists across our robustness tests and may reflect smaller effective kinematic warp onset radii for the intermediate-age populations. The observed velocity differences may arise from the combined effects of earlier perturbations and the present-day warp, or from differences in vertical structure among stellar populations.
ER -