Mid-infrared spectra of high-redshift (z > 2) radio galaxies
We present the first mid-infrared Spitzer/Infraxed Spectrograph (IRS) observations of powerful radio galaxies at z > 2. These radio galaxies, 4C +23.56 (z = 2.48) and 6C J1908+7220 (z = 3.53), both show strong midinfrared continua, but with 6C J1908+7220 also showing strong PAH emission at re...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal Article |
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Institute of Physics Publishing
2008
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| Online Access: | http://hdl.handle.net/20.500.11937/21360 |
| _version_ | 1848750568298774528 |
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| author | Seymour, Nick Ogle, P. De Breuck, C. Fazio, G. Galametz, A. Haas, M. Lacy, M. Sajina, A. Stern, D. Willner, S. Vernet, J. |
| author_facet | Seymour, Nick Ogle, P. De Breuck, C. Fazio, G. Galametz, A. Haas, M. Lacy, M. Sajina, A. Stern, D. Willner, S. Vernet, J. |
| author_sort | Seymour, Nick |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We present the first mid-infrared Spitzer/Infraxed Spectrograph (IRS) observations of powerful radio galaxies at z > 2. These radio galaxies, 4C +23.56 (z = 2.48) and 6C J1908+7220 (z = 3.53), both show strong midinfrared continua, but with 6C J1908+7220 also showing strong PAH emission at rest-frame 6.2 and 7.7 µm. In 4C +23.56 we see no obvious PAH features above the continuum. The PAH emission in 6C J1908+7220 is the among the most distant observed to date and implies that there is a large instantaneous star formation rate (SFR). This is consistent with the strong detection of 6C J1908+7220 at far-IR and sub-mm wavelengths, indicative of large amounts of cold dust, ~109 M? Powerful radio galaxies at lower redshifts tend to have weak or undetectable PAH features and typically have lower far-IR luminosities. In addition, 4C +23.56 shows moderate silicate absorption as seen in less luminous radio galaxies, indicating T 9.7 µm = 0.3 ± 0.05. This feature is shifted out of the observed wavelength range for 6C J1908+7220. The correlation of strong PAH features with large amounts of cold dust, despite the presence of a powerful AGN, is in agreement with other recent results and implies that star formation at high redshift is. in some cases at least, associated with powerful, obscured AGN. © 2008, The American Astronomical Society. All rights reserved. |
| first_indexed | 2025-11-14T07:38:54Z |
| format | Journal Article |
| id | curtin-20.500.11937-21360 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T07:38:54Z |
| publishDate | 2008 |
| publisher | Institute of Physics Publishing |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-213602023-02-22T06:24:17Z Mid-infrared spectra of high-redshift (z > 2) radio galaxies Seymour, Nick Ogle, P. De Breuck, C. Fazio, G. Galametz, A. Haas, M. Lacy, M. Sajina, A. Stern, D. Willner, S. Vernet, J. We present the first mid-infrared Spitzer/Infraxed Spectrograph (IRS) observations of powerful radio galaxies at z > 2. These radio galaxies, 4C +23.56 (z = 2.48) and 6C J1908+7220 (z = 3.53), both show strong midinfrared continua, but with 6C J1908+7220 also showing strong PAH emission at rest-frame 6.2 and 7.7 µm. In 4C +23.56 we see no obvious PAH features above the continuum. The PAH emission in 6C J1908+7220 is the among the most distant observed to date and implies that there is a large instantaneous star formation rate (SFR). This is consistent with the strong detection of 6C J1908+7220 at far-IR and sub-mm wavelengths, indicative of large amounts of cold dust, ~109 M? Powerful radio galaxies at lower redshifts tend to have weak or undetectable PAH features and typically have lower far-IR luminosities. In addition, 4C +23.56 shows moderate silicate absorption as seen in less luminous radio galaxies, indicating T 9.7 µm = 0.3 ± 0.05. This feature is shifted out of the observed wavelength range for 6C J1908+7220. The correlation of strong PAH features with large amounts of cold dust, despite the presence of a powerful AGN, is in agreement with other recent results and implies that star formation at high redshift is. in some cases at least, associated with powerful, obscured AGN. © 2008, The American Astronomical Society. All rights reserved. 2008 Journal Article http://hdl.handle.net/20.500.11937/21360 10.1086/590081 Institute of Physics Publishing unknown |
| spellingShingle | Seymour, Nick Ogle, P. De Breuck, C. Fazio, G. Galametz, A. Haas, M. Lacy, M. Sajina, A. Stern, D. Willner, S. Vernet, J. Mid-infrared spectra of high-redshift (z > 2) radio galaxies |
| title | Mid-infrared spectra of high-redshift (z > 2) radio galaxies |
| title_full | Mid-infrared spectra of high-redshift (z > 2) radio galaxies |
| title_fullStr | Mid-infrared spectra of high-redshift (z > 2) radio galaxies |
| title_full_unstemmed | Mid-infrared spectra of high-redshift (z > 2) radio galaxies |
| title_short | Mid-infrared spectra of high-redshift (z > 2) radio galaxies |
| title_sort | mid-infrared spectra of high-redshift (z > 2) radio galaxies |
| url | http://hdl.handle.net/20.500.11937/21360 |