Helium II reverberation in NGC 5548. Aaron Patrick LaCluyze

ISBN: 9780549837350

Published:

NOOKstudy eTextbook

141 pages


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Helium II reverberation in NGC 5548.  by  Aaron Patrick LaCluyze

Helium II reverberation in NGC 5548. by Aaron Patrick LaCluyze
| NOOKstudy eTextbook | PDF, EPUB, FB2, DjVu, AUDIO, mp3, ZIP | 141 pages | ISBN: 9780549837350 | 5.43 Mb

Despite decades of study, the exact nature of the central engines of Active Galactic Nuclei (AGN) is still a mystery to be solved. Although great strides have been made, there are some outstanding questions that still need to be resolved, and newMoreDespite decades of study, the exact nature of the central engines of Active Galactic Nuclei (AGN) is still a mystery to be solved.

Although great strides have been made, there are some outstanding questions that still need to be resolved, and new tools are needed to answer them. The goal of this project was to craft a new method to accurately measure highly blended weak emission lines in AGN.

In particular, the reverberation behavior of He II lambda4686 and He II lambda1640 were investigated to reconcile a discrepancy between theoretical models, which predicted that the two lines should have the same lagtime and previous observational studies, which found that the optical line had a reverberation lag several times longer than the UV line.-The optical and UV He II emission lines were measured to have a reverberation lag time of 5-6 days, with good overlap between the two lines.

Furthermore, a previously measured strong lines, C IV, which were also involved in the heavy blending, was measured to have a lagtime consistent with previous measurements. This helps to validate the technique that was used. This technique, which required a large software development effort, included using an automated fitting routine to simultaneously fit multiple emission line template profiles that were, themselves, created from observed data.-One rather surprising result was the clear indication that He II and C IV are not created by the same gas within the BELR.

This is contrary to what was predicted by the typical model of the BELR but consistent with previous measurements.



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