The Spitzer mid-infrared active galactic nucleus survey. I. Optical and near-infrared spectroscopy of obscured candidates and normal active galactic nuclei selected in the mid-infrared
We present the results of a program of optical and near-infrared spectroscopic follow-up of candidate active galactic nuclei (AGNs) selected in the mid-infrared. This survey selects both normal and obscured AGNs closely matched in luminosity across a wide range, from Seyfert galaxies with bolometric...
| Main Authors: | , , , , , , , , , , |
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| Format: | Journal Article |
| Published: |
2013
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| Online Access: | http://hdl.handle.net/20.500.11937/9597 |
| _version_ | 1848745995373903872 |
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| author | Lacy, M. Ridgway, S. Gates, E. Nielsen, D. Petric, A. Sajina, A. Urrutia, T. Cox Drews, S. Harrison, C. Seymour, Nick Storrie-Lombardi, L. |
| author_facet | Lacy, M. Ridgway, S. Gates, E. Nielsen, D. Petric, A. Sajina, A. Urrutia, T. Cox Drews, S. Harrison, C. Seymour, Nick Storrie-Lombardi, L. |
| author_sort | Lacy, M. |
| building | Curtin Institutional Repository |
| collection | Online Access |
| description | We present the results of a program of optical and near-infrared spectroscopic follow-up of candidate active galactic nuclei (AGNs) selected in the mid-infrared. This survey selects both normal and obscured AGNs closely matched in luminosity across a wide range, from Seyfert galaxies with bolometric luminosities L bol ~ 1010 L ☉ to highly luminous quasars (L bol ~ 1014 L ☉), all with redshifts ranging from 0 to 4.3. Samples of candidate AGNs were selected with mid-infrared color cuts at several different 24 μm flux density limits to ensure a range of luminosities at a given redshift. The survey consists of 786 candidate AGNs and quasars, of which 672 have spectroscopic redshifts and classifications. Of these, 137 (20%) are type 1 AGNs with blue continua, 294 (44%) are type 2 objects with extinctions AV ~>5 toward their AGNs, 96 (14%) are AGNs with lower extinctions (AV ~ 1), and 145 (22%) have redshifts, but no clear signs of AGN activity in their spectra. Of the survey objects 50% have L bol > 1012 L ☉, in the quasar regime. We present composite spectra for type 2 quasars and objects with no signs of AGN activity in their spectra. We also discuss the mid-infrared—emission-line luminosity correlation and present the results of cross correlations with serendipitous X-ray and radio sources. The results show that: (1) obscured objects dominate the overall AGN population, (2) mid-infrared selected AGN candidates exist which lack AGN signatures in their optical spectra but have AGN-like X-ray or radio counterparts, and (3) X-ray and optical classifications of obscured and unobscured AGNs often differ. |
| first_indexed | 2025-11-14T06:26:13Z |
| format | Journal Article |
| id | curtin-20.500.11937-9597 |
| institution | Curtin University Malaysia |
| institution_category | Local University |
| last_indexed | 2025-11-14T06:26:13Z |
| publishDate | 2013 |
| recordtype | eprints |
| repository_type | Digital Repository |
| spelling | curtin-20.500.11937-95972023-02-22T06:24:17Z The Spitzer mid-infrared active galactic nucleus survey. I. Optical and near-infrared spectroscopy of obscured candidates and normal active galactic nuclei selected in the mid-infrared Lacy, M. Ridgway, S. Gates, E. Nielsen, D. Petric, A. Sajina, A. Urrutia, T. Cox Drews, S. Harrison, C. Seymour, Nick Storrie-Lombardi, L. We present the results of a program of optical and near-infrared spectroscopic follow-up of candidate active galactic nuclei (AGNs) selected in the mid-infrared. This survey selects both normal and obscured AGNs closely matched in luminosity across a wide range, from Seyfert galaxies with bolometric luminosities L bol ~ 1010 L ☉ to highly luminous quasars (L bol ~ 1014 L ☉), all with redshifts ranging from 0 to 4.3. Samples of candidate AGNs were selected with mid-infrared color cuts at several different 24 μm flux density limits to ensure a range of luminosities at a given redshift. The survey consists of 786 candidate AGNs and quasars, of which 672 have spectroscopic redshifts and classifications. Of these, 137 (20%) are type 1 AGNs with blue continua, 294 (44%) are type 2 objects with extinctions AV ~>5 toward their AGNs, 96 (14%) are AGNs with lower extinctions (AV ~ 1), and 145 (22%) have redshifts, but no clear signs of AGN activity in their spectra. Of the survey objects 50% have L bol > 1012 L ☉, in the quasar regime. We present composite spectra for type 2 quasars and objects with no signs of AGN activity in their spectra. We also discuss the mid-infrared—emission-line luminosity correlation and present the results of cross correlations with serendipitous X-ray and radio sources. The results show that: (1) obscured objects dominate the overall AGN population, (2) mid-infrared selected AGN candidates exist which lack AGN signatures in their optical spectra but have AGN-like X-ray or radio counterparts, and (3) X-ray and optical classifications of obscured and unobscured AGNs often differ. 2013 Journal Article http://hdl.handle.net/20.500.11937/9597 10.1088/0067-0049/208/2/24 unknown |
| spellingShingle | Lacy, M. Ridgway, S. Gates, E. Nielsen, D. Petric, A. Sajina, A. Urrutia, T. Cox Drews, S. Harrison, C. Seymour, Nick Storrie-Lombardi, L. The Spitzer mid-infrared active galactic nucleus survey. I. Optical and near-infrared spectroscopy of obscured candidates and normal active galactic nuclei selected in the mid-infrared |
| title | The Spitzer mid-infrared active galactic nucleus survey. I. Optical and near-infrared spectroscopy of obscured candidates and normal active galactic nuclei selected in the mid-infrared |
| title_full | The Spitzer mid-infrared active galactic nucleus survey. I. Optical and near-infrared spectroscopy of obscured candidates and normal active galactic nuclei selected in the mid-infrared |
| title_fullStr | The Spitzer mid-infrared active galactic nucleus survey. I. Optical and near-infrared spectroscopy of obscured candidates and normal active galactic nuclei selected in the mid-infrared |
| title_full_unstemmed | The Spitzer mid-infrared active galactic nucleus survey. I. Optical and near-infrared spectroscopy of obscured candidates and normal active galactic nuclei selected in the mid-infrared |
| title_short | The Spitzer mid-infrared active galactic nucleus survey. I. Optical and near-infrared spectroscopy of obscured candidates and normal active galactic nuclei selected in the mid-infrared |
| title_sort | spitzer mid-infrared active galactic nucleus survey. i. optical and near-infrared spectroscopy of obscured candidates and normal active galactic nuclei selected in the mid-infrared |
| url | http://hdl.handle.net/20.500.11937/9597 |