Until now,Einstein's general relativity is the most successful gravitational theory.However,this theory faces difficulties on both the theoretical side and the observational side,including the singularity problem in black holes and cosmology,the quantization problem,the dark matter,and the dark energy problems.Therefore,the testing of gravity in various environments is one of the most important tasks for physics and astronomy.The discovery of gravitational-wave(GW)events by the Laser Interferometer Gravitational-Wave Observatory(LIGO)and other detectors provides a novel way to realize it.Different from other methods,the GWs generated by the coalescence of compact binaries are currently the unique detected GW sources,providing a novel probe to test gravitational theory in the strong gravitational field environment for the first time.The key role of gravity testing is to compare general relativity and other modified gravitational theories through the observational data,to obtain falsification of the theory or constraints of model parameters.In this review,we focus on this type of GW source and combine the observation results of current ground-based laser interferometer GW detectors to introduce the basic methods of using GWs to test gravity,as well as the measurement accuracy that may be obtained at present or in the future.Firstly,we briefly introduce the calculation method of GW waveforms of compact binary mergers in the general gravitational theory.We present the main characters of GWs in general relativity and the possible deviations in the modified gravities.Then,we introduce two different testing methods:The model-dependent method and the model-independent method.The former one can test the gravitational theories by calculating the explicit GW waveforms in various theories,and compare them with the observational data to constrain or falsify the corresponding gravitational theories.The latter can test some specific features of gravity with observational data,and the results can be used to constrain a class of theories.For the model-dependent method,we introduce three typical models,including the Brans-Dicke gravity,which is the first relativistic modified gravity;the general screened modified gravity,which includes the large class of modified gravities introduced to both interpret the cosmic acceleration and meet various tests in solar systems;the general parity-violating gravity,which includes a class of modified gravities with parity-violating terms.For the model-independent method,we introduce the basic ideas and test a set of features of gravity with current observations,including the phase parameters,velocity,dispersion relation,luminosity distance of GWs,and the parity symmetry of gravity.Although in this review,only the tests of gravity for the current ground-based GW detectors are introduced,the GW observations by the future space-based laser interferometers,the pulsar timing arrays,and the cosmic microwave background radiation detectors are hopeful to greatly improve the test capabilities in different aspects.
gravitational wavetest of gravitygeneral relativitymodified gravity
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维普
