Implications for unified schemes from the quasar fraction and emission-line luminosities in radio-selected samples
We use a principal components analysis of radio-selected (3CRR, 6CE and 7CRS) AGN datasets to define two parameters related to low-frequency (151 MHz) radio luminosity L_151 and [OIII] luminosity L_[OIII]: a parameter alpha encoding the L_151 - L_[OIII] correlation and a parameter beta encoding scat...
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| Format: | Journal article |
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2003
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| _version_ | 1797067996715286528 |
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| author | Grimes, J Rawlings, S Willott, C |
| author_facet | Grimes, J Rawlings, S Willott, C |
| author_sort | Grimes, J |
| collection | OXFORD |
| description | We use a principal components analysis of radio-selected (3CRR, 6CE and 7CRS) AGN datasets to define two parameters related to low-frequency (151 MHz) radio luminosity L_151 and [OIII] luminosity L_[OIII]: a parameter alpha encoding the L_151 - L_[OIII] correlation and a parameter beta encoding scatter about this correlation. We describe methods for constructing generalized luminosity functions (GLFs) based on alpha, beta, redshift and schemes for unifying quasars and radio galaxies. Luminosity-dependent unified schemes (e.g. a receding-torus scheme) have been invoked to explain the low quasar to radio galaxy fraction at low alpha and the differences in emission-line luminosities of radio quasars and radio galaxies. With the constraints of the 3CRR, 6CE and 7CRS datasets and radio source counts, our GLF approach was used to determine whether a receding-torus-like scheme is required if there are two populations of radio sources: one at low alpha, consisting of 'starved AGN'; the other at high alpha consisting of 'Eddington-tuned AGN'. Because of the overlap between these two populations and the effects of the beta parameter, schemes with or without a receding torus can produce a low quasar fraction at low alpha and differences in [OIII] luminosity between radio galaxies and quasars. The receding torus may be a physical process important in one or more populations of radio sources, but this is not yet proved either by the quasar fraction or the emission-line properties of radio-selected samples. |
| first_indexed | 2024-03-06T22:04:21Z |
| format | Journal article |
| id | oxford-uuid:4fa579f2-ed37-4376-8446-5f0ca2dae7bf |
| institution | University of Oxford |
| last_indexed | 2024-03-06T22:04:21Z |
| publishDate | 2003 |
| record_format | dspace |
| spelling | oxford-uuid:4fa579f2-ed37-4376-8446-5f0ca2dae7bf2022-03-26T16:08:34ZImplications for unified schemes from the quasar fraction and emission-line luminosities in radio-selected samplesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:4fa579f2-ed37-4376-8446-5f0ca2dae7bfSymplectic Elements at Oxford2003Grimes, JRawlings, SWillott, CWe use a principal components analysis of radio-selected (3CRR, 6CE and 7CRS) AGN datasets to define two parameters related to low-frequency (151 MHz) radio luminosity L_151 and [OIII] luminosity L_[OIII]: a parameter alpha encoding the L_151 - L_[OIII] correlation and a parameter beta encoding scatter about this correlation. We describe methods for constructing generalized luminosity functions (GLFs) based on alpha, beta, redshift and schemes for unifying quasars and radio galaxies. Luminosity-dependent unified schemes (e.g. a receding-torus scheme) have been invoked to explain the low quasar to radio galaxy fraction at low alpha and the differences in emission-line luminosities of radio quasars and radio galaxies. With the constraints of the 3CRR, 6CE and 7CRS datasets and radio source counts, our GLF approach was used to determine whether a receding-torus-like scheme is required if there are two populations of radio sources: one at low alpha, consisting of 'starved AGN'; the other at high alpha consisting of 'Eddington-tuned AGN'. Because of the overlap between these two populations and the effects of the beta parameter, schemes with or without a receding torus can produce a low quasar fraction at low alpha and differences in [OIII] luminosity between radio galaxies and quasars. The receding torus may be a physical process important in one or more populations of radio sources, but this is not yet proved either by the quasar fraction or the emission-line properties of radio-selected samples. |
| spellingShingle | Grimes, J Rawlings, S Willott, C Implications for unified schemes from the quasar fraction and emission-line luminosities in radio-selected samples |
| title | Implications for unified schemes from the quasar fraction and
emission-line luminosities in radio-selected samples |
| title_full | Implications for unified schemes from the quasar fraction and
emission-line luminosities in radio-selected samples |
| title_fullStr | Implications for unified schemes from the quasar fraction and
emission-line luminosities in radio-selected samples |
| title_full_unstemmed | Implications for unified schemes from the quasar fraction and
emission-line luminosities in radio-selected samples |
| title_short | Implications for unified schemes from the quasar fraction and
emission-line luminosities in radio-selected samples |
| title_sort | implications for unified schemes from the quasar fraction and emission line luminosities in radio selected samples |
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