Probing Photons Coupled To Weyl Tensor In The Solar System

As an extremely powerful tool for investigating the fundamental interaction be-tween the electromagnetic and gravitational fields,propagation of light in the gravi-tational field provides lots of information about the nature of these two fundamental fields.High-precision experiments and measurements impose opportunities for testing the idea about how photons couple to gravitational field and for detecting some tiny effects beyond the standard Einstein-Maxwell model,providing deeply understandings of their fundamental interaction.With the purpose of deeply understanding the fundamental interaction between the electromagnetic and gravitational fields,photons coupled to the Weyl tensor with two polarizations was proposed,which could be derived from the Maxwell equation with a Weyl correction and denotes the gravitational distortion.This correction with respect to general relativity in a 4-dimensional spacetime can be characterized by a coupling strength parameter a.Thus,we are motivated by testing the theory and mainly try to research these deeply.By taking such a coupling into account,we firstly investigateits effects on the classical tests in the Solar System,including the deflection of light,the gravitational time delay and the Cassini tracking experiment,and constrain the param-S eter a with new datasets.'None of these works were done before and these data of the experiments are used for testing the photons coupled to the Weyl tensor for the first time.We find that the experimental upper bounds are |?|?4 × 1011-5×1013m2,in which the strongest bound comes from the Cassini tracking.Therefore,it is expected that when more sophisticated frequency standards can be implemented in the spacecraft stracking in the future,this boundon a will be reduced further.Secondly,a new test called by gravitational time advancement is proposed and investigated to test such the coupling.This new test,which is quite different from Shapiro time delay,depends strongly on round-trip proper time span(not coordinate time one)of flight of radio pulses between an observer on the Earth and a distant spacecraft.For ranging a spacecraft getting far away from the Sun,two special cases(the superior/inferior conjunctions)are used to analyse the observability in the advancement contributed by the Weyl coupling.We found that the situation of the inferior conjunction is more suitable for detecting the ad-vancement caused by such the Weyl coupling.In either case,two kinds of polarizations make the advancement in the model smaller or larger than the one of general relativ-ity.Although the observability in the advancement could be out of the reach of already existing technology,the implement of planetary laser ranging and optical clocks might provide us more insights on such the Weyl coupling in the near future.This thesis consists of five chapters.The first chapter briefly introduces some historical background and the current situation of research on modified gravity.The second chapter is devoted to introduce the photons coupled to the Weyl tensor.The other chapters from 3 to 4 are composed of the author's research projects during the master study period.In the third chapter,we study the influences of the photons coupled to the Weyl tensor on the Solar System classical tests for the first time by using available datasets.Then the observability of gravitational time advancement in the Solar System for this coupling is investigated in the fourth chapter.In the last chapter,conclusions and prospects are outlined.