Redetermination of Galactic Spiral Density Wave Parameters Based on Spectral Analysis of Maser Radial Velocities

Abstract

To redetermine the Galactic spiral density wave parameters, we have performed a spectral (Fourier) analysis of the radial velocities for 44 masers with known trigonometric parallaxes, proper motions, and line-of-sight velocities. The masers are distributed in a wide range of Galactocentric distances $(3.5<R<13.2$ kpc) and are characterized by a wide scatter of position angles $\theta$ in the Galactic XY plane. This has required an accurate allowance for the dependence of the perturbation phase both on the logarithm of the Galactocentric distances and on the position angles of the objects. To increase the significance of the extraction of periodicities from data series with large gaps, we have proposed and implemented a spectrum reconstruction method based on a generalized maximum entropy method. As a result, we have extracted a periodicity describing a spiral density wave with the following parameters from the maser radial velocities: the perturbation amplitude $f_R=7.7_{-1.5}^{+1.7}$ km s${}^{-1}$, the perturbation wavelength $\lambda =2.2_{-0.1}^{+0.4}$ kpc, the pitch angle of the spiral density wave $i=-5_{-0.9^{\circ }}^{+0.2^{\circ }}$, and the phase of the Sun in the spiral density wave ${\chi }_{\odot }=-147_{-17^{\circ }}^{+3^{\circ }}$.

20 pages, 4 figures

References in corpus (5)

• Trigonometric Parallaxes of Massive Star Forming Regions: VI. Galactic Structure, Fundamental Parameters and Non-Circular Motions
• The distance to the Orion Nebula
• Galactic masers and the Milky Way circular velocity
• A Parallactic Distance of 389 +24/-21 parsecs to the Orion Nebula Cluster from Very Long Baseline Array Observations
• Periodic Pattern in the Residual-Velocity Field of OB Associations

Cited by in corpus (3)

• Estimation of the Galactic Spiral Pattern Speed from Cepheids
• Estimation of the SolarGalactocentric Distance and Rotation Velocity from Near-Solar-Circle Objects
• Corrections for the Lutz-Kelker Bias for Galactic Masers