Gravitational waves in Einstein-{\AE}ther theory and generalized TeVeS theory after GW170817

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In this paper, the polarization contents of Einstein-\ae ther theory and the generalized TeVeS theory are studied.

• The Einstein-\ae ther theory has five polarizations, while the generalized TeVeS theory has six.
• In particular, transverse and longitudinal breathing polarization are mixed.
• The~possibility of using pulsar timing arrays to detect the extra polarizations in Einstein-\ae{}ther theory was also investigated.