OJ287:Post-Newtonian Calulation In Harmonic Coordinate And Pulsar Timing Residual Confirmation

We calculate the gravitational radiation by the binary black hole OJ287based on Post-Newtonian approximation in a harmonic coordinate. The timing residual obtained from waveform, compared with data from timing observations of the radio pulsar PSR B1855+09, further shows hypothesis referring to OJ287as a binary BH system might be proper. Under a chosen initial condition, both orbits of primary and the secondar yexperience a shifting due to the motion of the center of mass. The energy flux of gravitational radiation from binary is also provided, from which we find that the flux changes sign successively:EN>0, E1PN<0, E2PN>0, in a complete agreement with the relative signs of forces of each PN order, revealed in the previous work.The relative orbit in the harmonic coordinate is close to that in the center-of-mass frame. We also discuss other two sets of initial conditions as example, and find that the problem of initial condition in the harmonic coordinate is nontrivial.