S/N values of the promising sources for various detectors and observation durations. The circles, squares, filled pluses, rhombuses, and pentagons represent the TianQin, LISA, Taiji, DECIGO, and BBO results, respectively. The data points situated on the horizontal gray line corresponding to each source signify the S/N values calculated for T_obs = 4 yr. The S/N values calculated for T_obs = 2 yr and T_obs = 8 yr are shown in the lower and upper sides of the horizontal gray line, respectively. The vertical dashed gray line denotes S/N_thr = 5. Sources with S/N ≳ S/N_thr are regarded as detectable. Sources with S/N ≥ 1 indicate that the GW signals lie above the sensitivity curves of the corresponding detectors.