VLBI with SKA: Possible Arrays and Astrometric Science

TL;DR

The paper discusses the potential of SKA-VLBI to revolutionize astrometry by achieving microarcsecond precision, enabling detailed studies of celestial objects, testing general relativity, and improving the celestial reference frame.

Contribution

It explores the design possibilities of SKA-VLBI arrays and highlights their scientific applications in high-precision astrometry and fundamental physics.

Findings

Sensitivity increased by an order of magnitude

Astrometric precision below 10 microarcseconds achievable

Potential to test general relativity with high accuracy

Abstract

The next generation of very long baseline interferometry (VLBI) is stepping into the era of microarcsecond ($\mu$as) astronomy, and pushing astronomy, especially astrometry, to new heights. VLBI with the Square Kilometre Array (SKA), SKA-VLBI, will increase current sensitivity by an order of magnitude, and reach astrometric precision routinely below 10 $\mu$as, even challenging 1 $\mu$as. This advancement allows precise parallax and proper motion measurements of various celestial objects. Such improvements can be used to study objects (including isolated objects, and binary or multiple systems) in different stellar stages (such as star formation, main-sequence stars, asymptotic giant branch stars, pulsars, black holes, white dwarfs, etc.), unveil the structure and evolution of complex systems (such as the Milky Way), benchmark the international celestial reference frame, and reveal cosmic expansion. Furthermore, the theory of general relativity can also be tested with SKA-VLBI using precise measurements of light deflection under the gravitational fields of different solar system objects and the perihelion precession of solar system objects.