Timing residuals of the simulated datasets, with, and without Ṗ_b, which are Model 1 (blue) and Model 2 (orange), respectively, shown in the top panel. The middle panel illustrates the difference in the log-likelihood between two models with respect to the time in a MJD scale. The red-dotted lines indicate the significance of detection (≥3σ), either from fitting and from lnL. The color bar scale indicates the significance of the fitting of Ṗ_b. The detection is expected to be around 64 000–65 000 MJD. The lower panel indicates the expected measurements on Ṗ effect over time. The expected value and the 3σ uncertainty range of Ṗ_b are depicted with green and blue dotted lines, separately.