Discovery of a coherent, wave-like velocity pattern for the Radcliffe Wave

Abstract

Recently studies discovered that part of the Gould Belt belongs to a 2.7 kpc-long {coherent, thin} wave consisting of a chain of clouds, where a damped undulation pattern has been identified from the spatial arrangement of the clouds. We use the proper motions of Young Stellar Objects (YSOs) anchored inside the clouds to study the kinematic structure of the Radcliffe Wave in terms of $v_z$, and identify a damped, wave-like pattern from the $v_z$ space, which we call "velocity undulation". We propose a new formalism based on the Ensemble Empirical Mode Decomposition (EEMD) to determine the amplitude, period, and phase of the undulation pattern, and find that the spatial and the velocity undulation share an almost identical spatial frequency of about 1.5 kpc, and both are damped when measured from one side to the other. Measured for the first cycle, they exhibit a phase difference of around $2\pi /3$. The structure is oscillating around the midplane of the Milky Way disk with an amplitude of $\sim 130\pm 20\mathrm{pc}$. The vertical extent of the Radcliffe Wave exceeds the thickness of the molecular disk, suggesting that the undulation of the undulation signature might originate from a perturbation, e.g. the passage of a dwarf galaxy.

arXiv commentaccepted by MNRAS letter

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• The Radcliffe Wave is Oscillating
• The Great Wave: Evidence of a large-scale vertical corrugation propagating outwards in the Galactic disc
• Weather Forecast of the Milky Way: Shear and Stellar feedback determine the lives of Galactic-scale filaments
• Parallax-based Distances to Galactic Hii Regions: Nearby Spiral Structure
• The magnetic field of the Radcliffe Wave: starlight polarization at nearest approach to the Sun
• The Radcliffe Wave as traced by young open clusters: Stellar parameters, activity indicators, and abundances of solar-type members of eight young clusters
• The Radcliffe wave parameters from data on open star clusters
• The Impact of Expanding HII Regions on Filament G37:Curved Magnetic Field and Multiple Direction Material Flows
• Place of the Radcliffe Wave in the Local System