A sample of 6C radio sources designed to find objects at redshift > 4: II --- spectrophotometry and emission line properties
(Abridged) This is the second in a series of three papers which present and interpret basic observational data on the 6C* 151-MHz radio sample: a low-frequency selected sample which exploits filtering criteria based on radio properties (steep spectral index and small angular size) to find radio sour...
| Main Authors: | , , , , , , , , , |
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| Format: | Journal article |
| Language: | English |
| Published: |
2001
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| _version_ | 1797070643539214336 |
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| author | Jarvis, M Rawlings, S Lacy, M Blundell, K Bunker, A Eales, S Saunders, R Spinrad, H Stern, D Willott, C |
| author_facet | Jarvis, M Rawlings, S Lacy, M Blundell, K Bunker, A Eales, S Saunders, R Spinrad, H Stern, D Willott, C |
| author_sort | Jarvis, M |
| collection | OXFORD |
| description | (Abridged) This is the second in a series of three papers which present and interpret basic observational data on the 6C* 151-MHz radio sample: a low-frequency selected sample which exploits filtering criteria based on radio properties (steep spectral index and small angular size) to find radio sources at redshift z > 4 within a 0.133sr patch of sky. We present results of a programme of optical spectroscopy which has yielded redshifts in the range 0.5 < z < 4.4 for the 29 sources in the sample, all but six of which are secure. We find that the fil tering criteria used for 6C* are very effective in excluding the low-redshift, low-luminosity radio sources: the median redshift of 6C* is z~1.9 compared to z~1.1 for a complete sample matched in 151-MHz flux density. By combining the emission-line dataset for the 6C* radio sources with those for the 3CRR, 6CE and 7CRS samples we establish that z > 1.75 radio galaxies follow a rough proportionality between Lyalpha- and 151 MHz-luminosity which, like similar correlations seen in samples of lower-redshift radio sources, are indicative of a primary link between the power in the source of the photoionising photons (most likely a hidden quasar nucleus) and the power carried by the radio jets. We argue that radio sources modify their environments and that the range of emission-line properties seen is determined more by the range of source age than by the range in ambient environment. This is in accord with the idea that all high-redshift, high-luminosity radio sources are triggered in similar environments, presumably recently collapsed massive structures. |
| first_indexed | 2024-03-06T22:41:51Z |
| format | Journal article |
| id | oxford-uuid:5bd8a219-37e0-481d-ac4f-839cf7a7053e |
| institution | University of Oxford |
| language | English |
| last_indexed | 2024-03-06T22:41:51Z |
| publishDate | 2001 |
| record_format | dspace |
| spelling | oxford-uuid:5bd8a219-37e0-481d-ac4f-839cf7a7053e2022-03-26T17:24:29ZA sample of 6C radio sources designed to find objects at redshift > 4: II --- spectrophotometry and emission line propertiesJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:5bd8a219-37e0-481d-ac4f-839cf7a7053eEnglishSymplectic Elements at Oxford2001Jarvis, MRawlings, SLacy, MBlundell, KBunker, AEales, SSaunders, RSpinrad, HStern, DWillott, C(Abridged) This is the second in a series of three papers which present and interpret basic observational data on the 6C* 151-MHz radio sample: a low-frequency selected sample which exploits filtering criteria based on radio properties (steep spectral index and small angular size) to find radio sources at redshift z > 4 within a 0.133sr patch of sky. We present results of a programme of optical spectroscopy which has yielded redshifts in the range 0.5 < z < 4.4 for the 29 sources in the sample, all but six of which are secure. We find that the fil tering criteria used for 6C* are very effective in excluding the low-redshift, low-luminosity radio sources: the median redshift of 6C* is z~1.9 compared to z~1.1 for a complete sample matched in 151-MHz flux density. By combining the emission-line dataset for the 6C* radio sources with those for the 3CRR, 6CE and 7CRS samples we establish that z > 1.75 radio galaxies follow a rough proportionality between Lyalpha- and 151 MHz-luminosity which, like similar correlations seen in samples of lower-redshift radio sources, are indicative of a primary link between the power in the source of the photoionising photons (most likely a hidden quasar nucleus) and the power carried by the radio jets. We argue that radio sources modify their environments and that the range of emission-line properties seen is determined more by the range of source age than by the range in ambient environment. This is in accord with the idea that all high-redshift, high-luminosity radio sources are triggered in similar environments, presumably recently collapsed massive structures. |
| spellingShingle | Jarvis, M Rawlings, S Lacy, M Blundell, K Bunker, A Eales, S Saunders, R Spinrad, H Stern, D Willott, C A sample of 6C radio sources designed to find objects at redshift > 4: II --- spectrophotometry and emission line properties |
| title | A sample of 6C radio sources designed to find objects at redshift > 4:
II --- spectrophotometry and emission line properties |
| title_full | A sample of 6C radio sources designed to find objects at redshift > 4:
II --- spectrophotometry and emission line properties |
| title_fullStr | A sample of 6C radio sources designed to find objects at redshift > 4:
II --- spectrophotometry and emission line properties |
| title_full_unstemmed | A sample of 6C radio sources designed to find objects at redshift > 4:
II --- spectrophotometry and emission line properties |
| title_short | A sample of 6C radio sources designed to find objects at redshift > 4:
II --- spectrophotometry and emission line properties |
| title_sort | sample of 6c radio sources designed to find objects at redshift gt 4 ii spectrophotometry and emission line properties |
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