3D Kinematics of Stellar SiO Masers in the Galactic Center

Abstract

We present 3D velocity measurements and acceleration limits for stars within a few parsec of the Galactic Center (GC) black hole, Sgr A*, based on observations of 43 and 86 GHz circumstellar maser emission. Observations were taken with the Very Large Array (VLA) in 2013, 2014, and 2020 and with the Atacama Large Millimeter/submillimeter Array (ALMA) in 2015 and 2017. We detect 28 masers in total, of which four are new detections. Combining these data with extant maser astrometry, we calculate stellar proper motions and accelerations with uncertainties as low as ~10 $\mu$as yr${}^{-1}$ and 0.5 $\mu$as yr${}^{-2}$, respectively, corresponding to approximately 0.5 km s${}^{-1}$ and 0.04 km s${}^{-1}$ yr${}^{-1}$ at a distance of 8 kpc. We measure radial velocities from maser spectra with ~0.5 km s${}^{-1}$ uncertainties, though the precision and accuracy of such measurements for deducing the underlying stellar velocities are limited by the complex spectral profiles of some masers. We therefore measure radial acceleration limits with typical uncertainties of ~0.1 km s${}^{-1}$ yr${}^{-1}$. We analyze the resulting 3D velocities and accelerations with respect to expected motions resulting from models of the mass distribution in the GC.

29 pages, 6 figures, accepted for publication in ApJ; updated to correspond with journal proof

References in corpus (9)

• Array Programming with NumPy
• The mass distribution and gravitational potential of the Milky Way
• Detection of the Schwarzschild precession in the orbit of the star S2 near the Galactic centre massive black hole
• An Improved Distance and Mass Estimate for Sgr A* from a Multistar Orbit Analysis
• Kinematics of the old stellar population at the Galactic Center
• The Galactic Center: An Improved Astrometric Reference Frame for Stellar Orbits around the Supermassive Black Hole
• The Megamaser Cosmology Project. XI. A geometric distance to CGCG 074-064
• Stellar masers, circumstellar envelopes, and supernova remnants
• Observations of the 86 GHz SiO maser sources in the Central Parsec of the Galactic Centre