Theory of Relativistic Reference Frames for High-Precision Astrometric Space Missions

TL;DR

This paper develops a comprehensive relativistic framework for high-precision space astrometry, essential for interpreting data from modern space missions that measure stellar and cosmological positions with microarcsecond accuracy.

Contribution

It introduces a hierarchical relativistic reference frame theory based on Einstein's general relativity, covering cosmological to local solar system scales, including light propagation in dynamic gravitational fields.

Findings

Hierarchical structure of relativistic reference frames described.

Inclusion of effects of time-dependent gravitational fields on light propagation.

Framework applicable to microarcsecond astrometry.

Abstract

Recent modern space missions deliver invaluable information about origin of our universe, physical processes in the vicinity of black holes and other exotic astrophysical objects, stellar dynamics of our galaxy, etc. On the other hand, space astrometric missions make it possible to determine with unparalleled precision distances to stars and cosmological objects as well as their physical characteristics and positions on the celestial sphere. Permanently growing accuracy of space astronomical observations and the urgent need for adequate data processing algorithms require corresponding development of an adequate theory of reference frames along with unambiguous description of propagation of light rays from a source of light to observer. Such a theory must be based on the Einstein's general relativity and account for numerous relativistic effects both in the solar system and outside of its boundary. The main features of the relativistic theory of reference frames are presented in this work. A hierarchy of the frames is described starting from the perturbed cosmological Friedmann-Robertson-Walker metric and going to the observer's frame through the intermediate barycentric and geocentric frames in the solar system. Microarcsecond astrometry and effects of propagation of light rays in time-dependent gravitational fields are discussed as well.