http://arxiv.org/abs/1806.08571
The concept of the quasar main sequence is very attractive since it stresses correlations between various parameters and implies the underlying simplicity. Usually, the Eddington ratio was considered to be the main physical driver behind the sequence. In this paper, we test the hypothesis that the actual driver is the peak of the broad band quasar spectrum, connected with the maximum temperature in the quasar accretion disk. With this aim, we perform the computations of the Fe II and H$\beta$ line production using the code CLOUDY, and we locate theoretical points on the optical plane. Our theoretically computed points cover well the optical plane part populated with the observed quasars, particularly if we allow for super-Solar abundance of heavy elements. Explanation of the exceptionally strong Fe II emitter requires a stronger contribution from the dark sides of the clouds. However, we conclude that there is no single simple driver behind the sequence, as neither Eddington ratio nor broad band spectrum shape plays the dominant role. Also, the role of the viewing angle in providing the dispersion of the quasar main sequence is apparently not as strong as expected.
S. Panda, B. Czerny, T. Adhikari, et. al.
Mon, 25 Jun 18
7/54
Comments: 16 pages, 13 figures, submitted to ApJ; Comments are welcome
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