English

Determination of the relativistic parameter gamma using very long baseline interferometry

General Relativity and Quantum Cosmology 2015-05-13 v1

Abstract

Relativistic bending in the vicinity of a massive body is characterized only by the post-Newtonian parameter γ\gamma within the standard parameterized post-Newtonian formalism, which is unity in General Relativity. Aiming at estimating this parameter, we use very long baseline interferometry (VLBI) to measure the gravitational deflection of radio waves emitted by distant compact radio sources, by Solar System bodies. We analyze geodetic VLBI observations recorded since 1979. We compare estimates of γ\gamma and errors obtained using various analysis schemes including global estimations over several time spans and with various Sun elongation cut-off angles, and analysis of radio source coordinate time series. We arrive at the conclusion that the relativistic parameter γ\gamma cannot be estimated at better than 2×1042\times10^{-4}. The main factor of limitation is the uncertainty in the determination of (global or session-wise) radio source coordinates. A sum of various instrumental and modeling errors and analysis strategy defects, that cannot be decorrelated and corrected yet, is at the origin of the limitating noise.

Keywords

Cite

@article{arxiv.0903.1615,
  title  = {Determination of the relativistic parameter gamma using very long baseline interferometry},
  author = {S. B. Lambert and C. Le Poncin-Lafitte},
  journal= {arXiv preprint arXiv:0903.1615},
  year   = {2015}
}

Comments

accepted for publication in Astronomy and Astrophysics

R2 v1 2026-06-21T12:19:58.910Z