MG13 - Talk detail

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Abstract

The periastron shift and the Lense-Thirring effect of bound orbital motion in a general axially symmetric space-time given by Plebanski and Demianski are analyzed. We also define a measure for the conicity of the orbit and give analytic expressions for the observables in terms of hyperelliptic integrals and Lauricella's F-function. For an interpretation of these analytical expressions, we perform a post-Schwarzschild and a post-Newton expansion of these quantities. This clearly shows the influence of the different space-time parameters on the considered observables and allows to characterize Kerr, Taub-NUT, Schwarzschild-de Sitter, or other space-times. This talk is based on Phys. Rev. D 85, 044049 (2012).

Session

Accepted

Yes

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Time

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Title

Abstract

The Pioneer Anomaly (PA) is a constant unexplained residual Doppler shift of the deep space probes Pioneer 10 and Pioneer 11. Many alternative gravity theories have been proposed to exlain this effect. It has also be suggested to investigate the thermal effects, since only a small fraction of the available thermal energy is sufficient to cause a recoil in the magnitude of the anomaly. However, the constancy of the effect and simple model calculations seemed to contradict a thermal source. We developed new high precision modeling methods for the assessment of thermal recoils acting on spacecraft and used them for a detailed thermal analysis of the complete Pioneer 10 mission. The analysis, which includes the detailed interior and exterior configuration of the craft as well as the available telemetry data shows that the observed residual effect can completely be reconstructed as a thermal recoil resulting from anisotropic heat radiation. For one part of the mission this result has already been confirmed independently and a new analysis of longer Doppler data sets by NASA also favour a thermal explanation of the PA. In the talk, the modelling methods based on Finite Elements and raytracing as well as the robustness of the results will be discussed in detail. This talk is based on Ann. Physik (Berlin) 523, 439 (2011).

Session

Accepted

Yes

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Time

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Title

Abstract

Standard fundamental equations of motion for point particles are of second order in the time derivative. Here we are exploring the consequences of fundamental equations of motion with an additional small even higher order term to the standard formulation. This is related to two issues: (i) higher order equations of motion will have influence on the definition of the structure of possible interactions and in particular of the gravitational interaction, and (ii) such equations of motion provide a framework to test the validity of Newton's second law which is the basis for the definition of forces but which assumes from the very beginning that the fundamental equations of motion are of second order. We will show that starting with our extended equations of motions it is possible to introduce the space--time metric describing the gravitational interaction by means of a standard gauge principle. Another main result of our model is that for slowly varying and smooth fields under the assumption of small changes with respect to the second order solution the higher order derivatives induces a zitterbewegung. We confront this higher order scheme with experimental data.

Session

Accepted

Yes

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Time

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Abstract

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