Maser Astrometry with VLBI and the SKA

TL;DR

The paper explores how the SKA integrated with VLBI can revolutionize maser astrometry, enabling precise distance measurements and large-scale surveys of the Milky Way and beyond.

Contribution

It introduces the potential of the SKA to significantly enhance maser astrometry with unprecedented sensitivity and accuracy, expanding observational capabilities.

Findings

Microarcsecond-level positioning accuracy for methanol masers.

Potential for large-scale Galactic and extragalactic maser surveys.

Enhanced understanding of Galactic structure and dynamics.

Abstract

We discuss the unique opportunities for maser astrometry with the inclusion of the Square Kilometre Array (SKA) in Very Long Baseline Interferometry (VLBI) networks. The first phase of the SKA will enable observations of hydroxyl and methanol masers, positioning the latter to an accuracy of 5 microarcseconds, and the second phase may allow water maser observations. These observations will provide trigonometric distances with errors as small as 1%. The unrivalled sensitivity of the SKA will enable large-scale surveys and, through joint operations, will turn any VLBI network into a fast astrometry device. Both evolved stars and high mass star formation regions will be accessible throughout the (Southern) Milky Way, completing our understanding of the content, dynamics and history of our Galaxy. Maser velocities and proper motions will be measurable in the Local Group of galaxies and beyond, providing new insights into their kinematics and evolution.