Can the Pioneer anomaly be of gravitational origin? A phenomenological answer

TL;DR

This paper investigates whether the Pioneer anomaly could have a gravitational origin by analyzing planetary data and testing modified gravity models, ultimately finding no supporting evidence for a gravitational explanation.

Contribution

It provides a comprehensive phenomenological analysis testing gravitational explanations for the Pioneer anomaly against planetary motion data.

Findings

No evidence supporting a gravitational origin of the Pioneer anomaly.

Modified gravity models do not explain the Pioneer anomaly based on planetary data.

Planetary motion remains consistent with standard gravitational theories.

Abstract

In order to satisfy the equivalence principle, any non-conventional mechanism proposed to gravitationally explain the Pioneer anomaly, in the form in which it is presently known from the so-far analyzed Pioneer 10/11 data, cannot leave out of consideration its impact on the motion of the planets of the Solar System as well, especially those orbiting in the regions in which the anomalous behavior of the Pioneer probes manifested itself. In this paper we, first, discuss the residuals of the right ascension \alpha and declination \delta of Uranus, Neptune and Pluto obtained by processing various data sets with different, well established dynamical theories (JPL DE, IAA EPM, VSOP). Second, we use the latest determinations of the perihelion secular advances of some planets in order to put on the test two gravitational mechanisms recently proposed to accommodate the Pioneer anomaly based on two models of modified gravity. Finally, we adopt the ranging data to Voyager 2 when it encountered Uranus and Neptune to perform a further, independent test of the hypothesis that a Pioneer-like acceleration can also affect the motion of the outer planets of the Solar System. The obtained answers are negative.