http://arxiv.org/abs/1505.04122
In our recent paper, we argued that the broad hydrogen lines, as well as the low-ionization lines in quasars, are significantly contributed by the Cerenkov quasi-line emission of the fast electrons in the dense clouds/filaments/sheets ($N_{\rm H}\geq 10^{14}~{\rm cm^{-3}}$); whereas this line-like radiation mechanism is invalid for producing the high ionization lines. Therefore, the observed broad hydrogen lines or low-ionization lines should be blended by both the real line emission via the bound-bound transition in atoms/ions and the Cerenkov quasi-line emission. In this paper, we provide an evidence quantitatively supporting above conclusions. Until now the observed different redshifts of different broad hydrogen lines is still a problem at issue. The Cerenkov line-like radiation mechanism provides a plausible resolution for this difficulty: it is the `Cerenkov line redshift’, which is different from line to line, causes the peculiar redshift-differences among Ly$\alpha$, H$\alpha$ and H$\beta$ lines. The good fitting to the observed redshifts of quasars confirms the existence of Cerenkov component in the broad hydrogen lines. Furthermore, we conclude that, in the blended Ly$\alpha$ line, the line-intensity of the Cerenkov component approximately equals that of the accompanying `normal line’ (an approximate equipartition of intensity between the two components in the broad Ly$\alpha$ line). This result quantitatively illustrates the importance of the Cerenkov component in the broad lines of quasars.
D. Liu, J. Shi, L. Chen, et. al.
Mon, 18 May 15
10/39
Comments: 14 pages, 1 figure, Submitted to ApJ
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