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Title: Active galactic nuclei and warm absorbers
Author: Momtahan, Kian
Awarding Body: University of Bristol
Current Institution: University of Bristol
Date of Award: 2013
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We present a study into the existence of the broad Fe Ka line, the hot nature of the ionised gas surrounding Active Galactic Nuclei, most commonly referred to as 'warm absorbers', and the AGN environment. We begin with an investigation of the Seyfert 1.5 galaxy NGC 3516. In our analysis, we use the Chandra telescope to explore the environment around the black hole, utilising the high resolution of the spectrometer to constrain the physical parameters. In conjunction with this we use the large effective area of Suzaku in order to detect subtle features such as the broad KO' feature. In this work we come to the conclusion that the effects of partial covering are insufficient to explain the existence of a broad Fe Ka feature. Interestingly enough however, they are required in order to provide an understanding of the soft X-ray region; although other models may provide an adequate explanation without the requirement for invoking partial covering. We go 011 to perform an analysis of 18 different Seyfert galaxies observed with the Chandra HETG, using an in-house pipeline. The purpose of the pipeline is to enable the automised fitting of phenomenological models to AGN, to aid with the diagnosis and study of warm absorbers. From this, we have determined that Seyfert 1 galaxies have negligible effect on the hard X-ray band, and that no correlation exists between the other Seyfert classifications and possible effects on the hard X-ray. We further identify a number of emission lines features throughout these AGN. Finally we investigate numerous possible relationships among the parameters of the warm absorbers in an attempt to understand the mechanism by which they are created. While this is inconclusive, we demonstrate that the mass ejection rate of the warm absorbers is low in comparison to the mass accretion rate and bolometric luminosity of the sources.
Supervisor: Not available Sponsor: Not available
Qualification Name: Thesis (Ph.D.) Qualification Level: Doctoral
EThOS ID:  DOI: Not available