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The Contribution of Čerenkov Line Radiation to the Broad Lines in AGNs1

Published online by Cambridge University Press:  12 April 2016

Hao Wu ,
Jian-rong Shi  and
Jun-han You
Hao Wu
Affiliation:
Institute for Space and Astrophysics, Department of Applied Physics, ShanghaiJiaotong University, Shanghai 200030, China
Jian-rong Shi
Affiliation:
Institute for Space and Astrophysics, Department of Applied Physics, ShanghaiJiaotong University, Shanghai 200030, China
Jun-han You
Affiliation:
Institute for Space and Astrophysics, Department of Applied Physics, ShanghaiJiaotong University, Shanghai 200030, China

Extract

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In 1980, You & Cheng (1980) suggested that in a dense gas medium, relativistic electrons will produce Čerenkov atomic or molecular emission lines of widths Δλ ≈ 1 – 10Å. The Čerenkov line is broader than a normal emission line and has small redshift (ΔZc ≡ Δλp/λlu ≈ 10–3), so the apparent velocity is about a few hundred km s−1. We refer to this as the ‘Čerenkov redshift’. In 1986, You & Cheng gave simplified formulae for Čerenkov line emission and the mechanism was confirmed by a series of elegant experiments (Xu et al. 1988, 1989). Recent progress in studies of AGNs, both in theory and observation, provide support for the Čerenkov line-emission model of the BLR of AGNs. In this paper, we prove that for a dense gas, if there are enough relativistic electrons, the Čerenkov line emission is strong enough to compare with the observations, and the Čerenkov line emission dominates over the spontaneous emission lines in the optically thick case.

Type
IV. Physics of the Broad-Line Region
Information
International Astronomical Union Colloquium , Volume 159: Emission Lines in Active Galaxies: New Methods and Techniques , 1997 , pp. 224 - 227
Copyright
Copyright © Astronomical Society of the Pacific 1997

Footnotes

1

This work is supported by National Natural Science Foundation of China.

References

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