Astronomy and Astrophysics – Astrophysics
Scientific paper
2000-05-10
Mon.Not.Roy.Astron.Soc. 317 (2000) 922
Astronomy and Astrophysics
Astrophysics
Accepted for publication in MNRAS
Scientific paper
10.1046/j.1365-8711.2000.03719.x
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.
Axon David J.
Robinson Alan
Robinson T. G.
Tadhunter Clive N.
No associations
LandOfFree
Testing the photoionization models of powerful radio galaxies: Mixed line-emitting media in 3C 321 does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Testing the photoionization models of powerful radio galaxies: Mixed line-emitting media in 3C 321, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Testing the photoionization models of powerful radio galaxies: Mixed line-emitting media in 3C 321 will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-636902