dc.contributor.author | Robinson, TG | en_US |
dc.contributor.author | Tadhunter, Clive | en_US |
dc.contributor.author | Axon, David | en_US |
dc.date.accessioned | 2006-05-31T13:11:58Z | en_US |
dc.date.available | 2006-05-31T13:11:58Z | en_US |
dc.date.issued | 2000-10 | en_US |
dc.identifier.citation | Monthly Notices of the Royal Astronomical Society 317 (2000) 922 | en_US |
dc.identifier.issn | 1365-2966 | en_US |
dc.identifier.uri | http://hdl.handle.net/1850/1896 | en_US |
dc.description | RIT community members may access full-text via RIT Libraries licensed databases: http://library.rit.edu/databases/ | |
dc.description.abstract | The photoionization models for the narrow emission line regions of powerful radio galaxies have yet to be tested in depth. To this end, we present high-quality long-slit spectroscopy of the powerful double-nucleus radio galaxy 3C 321. The data have good enough spatial resolution to be able to trace the variation in emission-line properties on kpc scales. Continuum modelling and subtraction enables the faint emission line fluxes to be measured in several regions across the emission line nebula. We plot diagnostic line-ratio diagrams and compare them with the predictions of various photoionization models, finding that the data is best fit by models which assume a mixture of optically thin and thick clouds illuminated by a power-law continuum.
The emission line kinematics, line ratios and deduced physical conditions show remarkably little variation across the source. We deduce a mean electron density of 400 +/- 120 cm-3 and a mean temperature of 11500 +/- 1500 K. Assuming a single population of optically thick line-emitting clouds, we calculate a mean photoionization parameter of (1.1 +/- 0.5) x 10e-2 and hence a photoionizing photon luminosity of Q ~ 10e55 -- 10e56 photon/s/sr. This indicates a central engine as luminous as that of the powerful quasar 3C 273, yet there is no evidence for such an energetically prolific central engine at either far-infrared or radio wavelengths. We therefore conclude that the mixed-media models, which give Q ~ 5 x 10e53 -- 5 x 10e54, represent a more likely scenario.
As a by-product of the continuum subtraction we infer that young stellar populations account for ~ 0.4% of the visible stellar mass in the galaxy, and that these populations are spatially extended. (Refer to PDF file for exact formulas). | en_US |
dc.description.sponsorship | STScI [Space Telescope Science Institute] is operated by the Association of Universities for Research in Astronomy, Inc. under NASA contract NAS 5-26555. | en_US |
dc.format.extent | 634262 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. 317 | en_US |
dc.relation.ispartofseries | issue 4 | en_US |
dc.relation.ispartofseries | p. 922 | en_US |
dc.subject | Galaxies-active | en_US |
dc.subject | Galaxies-individual (3C 321) | en_US |
dc.subject | Galaxies-kinematics and dynamics | en_US |
dc.subject | Quasars | en_US |
dc.subject | Stellar dynamics | en_US |
dc.title | Testing the photoionization models of powerful radio galaxies: Mixed line-emitting media in 3C 321 | en_US |
dc.type | Article | en_US |
dc.identifier.url | http://dx.doi.org/10.1046/j.1365-8711.2000.03719.x | |