2019MNRAS.490.1738Z

We extract the multiple-epoch Balmer-line profiles of the heavily obscured quasar 3C 445 from the spectral curves in the literature, and analyse the emission-line profiles of the H α and the H β lines and the profile variability in the H α line in the large time interval of more than three decades. The profile comparison between the H α and the H β lines shows that both Balmer lines share the profile with the same form, while the blue system of the H β line is seriously weaker than that of the H α line. Moreover, the blue system of the H α line suddenly disappeared completely and then did not appear again, however the other two components did not exhibit significant variation in the velocity or the amplitude. These findings suggest that the blue system of 3C 445, as with SDSS J153636.22+044127.0 and its analogues, is probably the result of the shock-heated outflowing gases. The observation angle of almost edge-on, which the previous studies suggested, can easily produce the high-speed and high-temperature shock in the collision between the massive outflow and the inner surface of the dusty torus.