dc.contributor.author | Smith, James | en_US |
dc.contributor.author | Robinson, Andrew | en_US |
dc.contributor.author | Young, Stuart | en_US |
dc.contributor.author | Axon, David | en_US |
dc.contributor.author | Corbett, Elizabeth | en_US |
dc.date.accessioned | 2006-05-23T18:33:13Z | en_US |
dc.date.available | 2006-05-23T18:33:13Z | en_US |
dc.date.issued | 2005-05 | en_US |
dc.identifier.citation | Monthly Notices of the Royal Astronomical Society 359 (2005) 846-864 | en_US |
dc.identifier.issn | 1365-2966 | en_US |
dc.identifier.uri | http://hdl.handle.net/1850/1873 | en_US |
dc.description | RIT community members may access full-text via RIT Libraries licensed databases: http://library.rit.edu/databases/ | |
dc.description.abstract | We present detailed scattering models confirming that distinctive variations in polarization across the broad Halpha line, which are observed in a significant fraction of Seyfert 1 galaxies, can be understood in terms of a rotating line-emitting disc surrounded by a co-planar scattering region (the equatorial scattering region). The predicted polarization properties are: averaged over wavelength, the position angle of polarization is aligned with the projected disc rotation axis and hence also with the radio source axis; (ii) the polarization PA rotates across the line profile, reaching equal but opposite (relative to the continuum PA) rotations in the blue and red wings; (iii) the degree of polarization peaks in the line wings and passes through a minimum in the line core. We identify 11 objects which exhibit these features to different degrees. In order to reproduce the large amplitude PA rotations observed in some cases, the scattering region must closely surround the emission disc and the latter must itself be a relatively narrow annulus -- presumably the Halpha-emitting zone of a larger accretion disc. Asymmetries in the polarization spectra may be attributable to several possible causes, including bulk radial infall in the equatorial scattering region, or contamination by polar scattered light. The broad Halpha lines do not, in general, exhibit double-peaked profiles, suggesting that a second Halpha-emitting component of the broad-line region is present, in addition to the disc. (Refer to PDF file for exact formulas). | en_US |
dc.description.sponsorship | JES acknowledges financial support from PPARC
via a post-graduate studentship and as a postdoctoral research assistant. This research has made use of the NASA/IPAC Extragalactic Database (NED) which is operated by the Jet Propulsion Laboratory, California Institute of Technology, under contract with the National Aeronautics and Space Administration. This work has partly been carried out using facilities and software provided by the STARLINK project. | en_US |
dc.format.extent | 783617 bytes | en_US |
dc.format.mimetype | application/pdf | en_US |
dc.language.iso | en_US | en_US |
dc.publisher | Blackwell Publishing: Monthly Notices of the Royal Astronomical Society | en_US |
dc.relation.ispartofseries | vol. 359 | en_US |
dc.relation.ispartofseries | issue 3 | en_US |
dc.relation.ispartofseries | pps. 846-864 | en_US |
dc.subject | Galaxies-active | en_US |
dc.subject | Galaxies-Seyfert | en_US |
dc.title | Equatorial scattering and the structure of the broad-line region in Seyfert nuclei: Evidence for a rotating disc | en_US |
dc.type | Article | en_US |
dc.identifier.url | http://dx.doi.org/10.1111/j.1365-2966.2005.08895.x | |