Constraints of General Screened Modified Gravities from Comprehensive Analysis of Binary Pulsars

Testing gravity using binary pulsars has become a key contemporary focus. Screened modified gravity is a kind of scalar-tensor theory with a screening mechanism in order to satisfy the tight solar system tests. In this paper, we investigate how the screening mechanism affects the orbital dynamics of binary pulsars, and calculate in detail the five post-Keplerian (PK) parameters in this theory. These parameters differ from those of general relativity (GR), and the differences are quantified by the scalar charges, which lead to the dipole radiation in this theory. We combine the observables of PK parameters for the 10 binary pulsars, respectively, to place the constraints on the scalar charges and possible deviations from GR. The dipole radiation in the neutron star (NS)-white dwarf (WD) binaries leads to more stringent constraints on deviations from GR. The most constraining systems for the scalar charges of NSs and WDs are PSR B1913+16 and PSR J1738+0333, respectively. The results of all tests exclude significant strong-field deviations and show good agreement with GR.