Evidence for a large fraction of Compton-thick quasars at high redshift
Using mid-infrared and radio selection criteria, we pre-select a sample of candidate high-redshift type-2 quasars in the Subaru XMM-Newton Deep Field (SXDF). To filter out starburst contaminants, we use a bayesian method to fit the spectral energy distributions (SEDs) between 24-microns and B-band,...
| Main Authors: | , , , , , , , , , |
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| פורמט: | Journal article |
| יצא לאור: |
2006
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| _version_ | 1826294030033485824 |
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| author | Martinez-Sansigre, A Rawlings, S Bonfield, D Mateos, S Simpson, C Watson, M Almaini, O Foucaud, S Sekiguchi, K Ueda, Y |
| author_facet | Martinez-Sansigre, A Rawlings, S Bonfield, D Mateos, S Simpson, C Watson, M Almaini, O Foucaud, S Sekiguchi, K Ueda, Y |
| author_sort | Martinez-Sansigre, A |
| collection | OXFORD |
| description | Using mid-infrared and radio selection criteria, we pre-select a sample of candidate high-redshift type-2 quasars in the Subaru XMM-Newton Deep Field (SXDF). To filter out starburst contaminants, we use a bayesian method to fit the spectral energy distributions (SEDs) between 24-microns and B-band, obtain photometric redshifts, and identify the best candidates for high-z type-2 quasars. This leaves us with 12 z_phot >= 1.7 type-2 quasar candidates in an area ~0.8 deg^2, of which only two have secure X-ray detections. The two detected sources have estimated column densities N_H~2 and 3x10^27 m^-2, i.e. heavily obscured but Compton-thin quasars. Given the large bolometric luminosities and redshifts of the undetected objects, the lack of X-ray detections suggests extreme absorbing columns N_H >= 10^28 m^-2 are typical. We have found evidence for a population of ``Compton-thick'' high-redshift type-2 quasars, at least comparable to, and probably larger than the type-1 quasar population, although spectroscopic confirmation of their AGN nature is important. |
| first_indexed | 2024-03-07T03:39:20Z |
| format | Journal article |
| id | oxford-uuid:bd585716-04ec-48c0-bfcd-7015e3a9fba4 |
| institution | University of Oxford |
| last_indexed | 2024-03-07T03:39:20Z |
| publishDate | 2006 |
| record_format | dspace |
| spelling | oxford-uuid:bd585716-04ec-48c0-bfcd-7015e3a9fba42022-03-27T05:31:09ZEvidence for a large fraction of Compton-thick quasars at high redshiftJournal articlehttp://purl.org/coar/resource_type/c_dcae04bcuuid:bd585716-04ec-48c0-bfcd-7015e3a9fba4Symplectic Elements at Oxford2006Martinez-Sansigre, ARawlings, SBonfield, DMateos, SSimpson, CWatson, MAlmaini, OFoucaud, SSekiguchi, KUeda, YUsing mid-infrared and radio selection criteria, we pre-select a sample of candidate high-redshift type-2 quasars in the Subaru XMM-Newton Deep Field (SXDF). To filter out starburst contaminants, we use a bayesian method to fit the spectral energy distributions (SEDs) between 24-microns and B-band, obtain photometric redshifts, and identify the best candidates for high-z type-2 quasars. This leaves us with 12 z_phot >= 1.7 type-2 quasar candidates in an area ~0.8 deg^2, of which only two have secure X-ray detections. The two detected sources have estimated column densities N_H~2 and 3x10^27 m^-2, i.e. heavily obscured but Compton-thin quasars. Given the large bolometric luminosities and redshifts of the undetected objects, the lack of X-ray detections suggests extreme absorbing columns N_H >= 10^28 m^-2 are typical. We have found evidence for a population of ``Compton-thick'' high-redshift type-2 quasars, at least comparable to, and probably larger than the type-1 quasar population, although spectroscopic confirmation of their AGN nature is important. |
| spellingShingle | Martinez-Sansigre, A Rawlings, S Bonfield, D Mateos, S Simpson, C Watson, M Almaini, O Foucaud, S Sekiguchi, K Ueda, Y Evidence for a large fraction of Compton-thick quasars at high redshift |
| title | Evidence for a large fraction of Compton-thick quasars at high redshift |
| title_full | Evidence for a large fraction of Compton-thick quasars at high redshift |
| title_fullStr | Evidence for a large fraction of Compton-thick quasars at high redshift |
| title_full_unstemmed | Evidence for a large fraction of Compton-thick quasars at high redshift |
| title_short | Evidence for a large fraction of Compton-thick quasars at high redshift |
| title_sort | evidence for a large fraction of compton thick quasars at high redshift |
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