Progress in Measurements of the Gravitational Bending of Radio Waves Using the Vlba

Abstract

We have used the Very Long Baseline Array (VLBA) at 43, 23 and 15 GHz to measure the solar gravitational deflection of radio waves among four radio sources during an 18-day period in October 2005. Using phase-referenced radio interferometry to fit the measured phase delay to the propagation equation of the parameterized post-Newtonian (PPN) formalism, we have determined the deflection parameter γ = 0.9998 ± 0.0003 (68% confidence level), in agreement with General Relativity. The results come mainly from 43 GHz observations where the refraction effects of the solar corona were negligible beyond 3 degrees from the sun. The purpose of this experiment is three-fold: to improve on the previous results in the gravitational bending experiments near the solar limb; to examine and evaluate the accuracy limits of terrestrial VLBI techniques; and to determine the prospects and outcomes of future experiments. Our conclusion is that a series of improved designed experiments with the VLBA could increase the presented accuracy by at least a factor of 4.With the demonstrated accuracy of the VLBA to measure relative positions of radio sources to 0.01 mas (Fomalont & Kopeikin 2003; Brunthaler et al. 2006), the gravitational bending could be measured potentially with the radio-interferometric technique to a few parts in 100,000, although the coronal refraction when observing within a few degrees of the sun produces large path-length changes. In this paper, we present the results from the measurement of γ performed with the Very Long Baseline Array (VLBA) in October 2005, and we suggest how more accurate measurements of γ can be obtained.

Improved determination ofγby VLBI

“…In a parallel study, Fomalont et al (2009) found agreement with General Relativity of 3 × 10 −4 using phase-referenced VLBA observations of 3C 279 and 3C 273 at 15, 23, and 43 GHz. Though the accuracy of their measurement does not compete with other studies, the authors pointed out that the precision of the determination of γ could be improved by scheduling specially designed VLBA experiments.…”

Dynamic Universe Model Explains the Variations of Gravitational Deflection Observations of Very-Long-Baseline Interferometry

“…Shapiro et al showed the variation in the Gravitational deflection angle with respect to solar elongation angle. Fomalont et al (2009) observed position changes with respect to session and Frequency. Fomalont et al (2010) reported larger errors which cannot be explained by conventional methods and difference should be zero if the GR prediction is correct.…”

Explaining Formation of Astronomical Jets Using Dynamic Universe Model

“…In some conditions as discussed above, these bodies produce such gravitational effects on the neutrons travelling in between these bodies, these neutrons will take such will take some paths which are perpendicular to the central plane of Galaxy near the Galaxy center. Though it is heavier for my purse, purchase of new computer became necessary to take the continual computational load [21,22].…”