The spitzer high-redshift radio galaxy survey
We present results from a comprehensive imaging survey of 70 radio galaxies at redshifts 1 < z < 5.2 using all three cameras on board the Spitzer Space Telescope. The resulting spectral energy distributions unambiguously show a stellar population in 46 sources and hot dust emission ass...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal Article |
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Institute of Physics Publishing
2010
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| Online Access: | http://hdl.handle.net/20.500.11937/41416 |
| _version_ | 1848756139997528064 |
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| author | De Breuck, C. Seymour, Nick Stern, D. Willner, S. Eisenhardt, P. Fazio, G. Galametz, A. Lacy, M. Rettura, A. Rocca-Volmerange, B. Vernet, J. |
| author_facet | De Breuck, C. Seymour, Nick Stern, D. Willner, S. Eisenhardt, P. Fazio, G. Galametz, A. Lacy, M. Rettura, A. Rocca-Volmerange, B. Vernet, J. |
| author_sort | De Breuck, C. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We present results from a comprehensive imaging survey of 70 radio galaxies at redshifts 1 < z < 5.2 using all three cameras on board the Spitzer Space Telescope. The resulting spectral energy distributions unambiguously show a stellar population in 46 sources and hot dust emission associated with the active nucleus in 59. Using a new rest-frame S3µm/S 1.6µm versus S5µm/S3µm criterion, we identify 42 sources where the rest-frame 1.6 µm emission from the stellar population can be measured. For these radio galaxies, the median stellar mass is high, 2×1011 M?, and remarkably constant within the range 1 < z < 3. At z >3, there is tentative evidence for a factor of two decrease in stellar mass. This suggests that radio galaxies have assembled the bulk of their stellar mass by z ~ 3, but confirmation by more detailed decomposition of stellar and active galactic nucleus (AGN) emission is needed. The rest-frame 500 MHz radio luminosities are only marginally correlated with stellar mass but are strongly correlated with the rest-frame 5 µm hot dust luminosity. This suggests that the radio galaxies have a large range of Eddington ratios.We also present newVery Large Array 4.86 and 8.46 GHz imaging of 14 radio galaxies and find that radio core dominance-an indicator of jet orientation-is strongly correlated with hot dust luminosity.While all of our targets were selected as narrow-lined, type 2 AGNs, this result can be understood in the context of orientation-dependent models if there is a continuous distribution of orientations from obscured type 2 to unobscured type 1 AGNs rather than a clear dichotomy. Finally, four radio galaxies have nearby (<6?) companions whose mid-IR colors are suggestive of their being AGNs. This may indicate an association between radio galaxy activity and major mergers. © 2010. The American Astronomical Society. |
| first_indexed | 2025-11-14T09:07:27Z |
| format | Journal Article |
| id | curtin-20.500.11937-41416 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T09:07:27Z |
| publishDate | 2010 |
| publisher | Institute of Physics Publishing |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-414162023-02-22T06:24:17Z The spitzer high-redshift radio galaxy survey De Breuck, C. Seymour, Nick Stern, D. Willner, S. Eisenhardt, P. Fazio, G. Galametz, A. Lacy, M. Rettura, A. Rocca-Volmerange, B. Vernet, J. We present results from a comprehensive imaging survey of 70 radio galaxies at redshifts 1 < z < 5.2 using all three cameras on board the Spitzer Space Telescope. The resulting spectral energy distributions unambiguously show a stellar population in 46 sources and hot dust emission associated with the active nucleus in 59. Using a new rest-frame S3µm/S 1.6µm versus S5µm/S3µm criterion, we identify 42 sources where the rest-frame 1.6 µm emission from the stellar population can be measured. For these radio galaxies, the median stellar mass is high, 2×1011 M?, and remarkably constant within the range 1 < z < 3. At z >3, there is tentative evidence for a factor of two decrease in stellar mass. This suggests that radio galaxies have assembled the bulk of their stellar mass by z ~ 3, but confirmation by more detailed decomposition of stellar and active galactic nucleus (AGN) emission is needed. The rest-frame 500 MHz radio luminosities are only marginally correlated with stellar mass but are strongly correlated with the rest-frame 5 µm hot dust luminosity. This suggests that the radio galaxies have a large range of Eddington ratios.We also present newVery Large Array 4.86 and 8.46 GHz imaging of 14 radio galaxies and find that radio core dominance-an indicator of jet orientation-is strongly correlated with hot dust luminosity.While all of our targets were selected as narrow-lined, type 2 AGNs, this result can be understood in the context of orientation-dependent models if there is a continuous distribution of orientations from obscured type 2 to unobscured type 1 AGNs rather than a clear dichotomy. Finally, four radio galaxies have nearby (<6?) companions whose mid-IR colors are suggestive of their being AGNs. This may indicate an association between radio galaxy activity and major mergers. © 2010. The American Astronomical Society. 2010 Journal Article http://hdl.handle.net/20.500.11937/41416 10.1088/0004-637X/725/1/36 Institute of Physics Publishing unknown |
| spellingShingle | De Breuck, C. Seymour, Nick Stern, D. Willner, S. Eisenhardt, P. Fazio, G. Galametz, A. Lacy, M. Rettura, A. Rocca-Volmerange, B. Vernet, J. The spitzer high-redshift radio galaxy survey |
| title | The spitzer high-redshift radio galaxy survey |
| title_full | The spitzer high-redshift radio galaxy survey |
| title_fullStr | The spitzer high-redshift radio galaxy survey |
| title_full_unstemmed | The spitzer high-redshift radio galaxy survey |
| title_short | The spitzer high-redshift radio galaxy survey |
| title_sort | spitzer high-redshift radio galaxy survey |
| url | http://hdl.handle.net/20.500.11937/41416 |