Detection of periodic variations in vertical velocities of Galactic masers

Abstract

We have collected literature data on Galactic masers with trigonometric parallaxes measured by means of VLBI. We have obtained series of residual tangential, ΔV_{circ}, and radial, ΔV_R, velocities for 107 masers. Based on these series, we have re-determined parameters of the Galactic spiral density wave using the method of spectral (periodogram) analysis. The tangential and radial perturbation amplitudes are f_θ=6.0+/-2.6 km/s and f_R=7.2+/-2.2 km/s, respectively; the perturbation wavelengths are λ_θ=3.2+/-0.5 kpc and λ_R=3.0+/-0.6 kpc for a four-armed spiral model, m=4. The phase of the Sun χ_0 in the spiral density wave is -79^\circ+/-14^\circ and -199^\circ+/-16^\circ from the residual tangential and radial velocities, respectively. The most interesting result of this work is detecting a wave in vertical spatial velocities W versus distance R from the Galactic rotation axis. From the spectral analysis, we have found the following characteristics of this wave: the perturbation wavelength is λ_W=3.4+/-0.7 kpc and the amplitude f_W=4.3+/-1.2 km/s.

5 pages, 4 figures, accepted by MNRAS Letters

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• Determination of the Spiral Pattern Speed in the Milky Way from Young Open Star Clusters
• Parameters of the Galactic Spiral Density Wave from Masers with Parallax Errors Less Than 10%
• Galactic Kinematics from Data on Open Star Clusters from the MWSC Catalogue
• Galactic Rotation Based on OB Stars from the Gaia DR2 Catalogue
• The Mysterious Radcliffe Wave
• Kinematics of the Galaxy from Young Open Star Clusters with Data from the Gaia EDR3 Catalogue
• The Spiral Pattern Speed in the Milky Way Galaxy