Increasing AGN sample completeness using long-term near-infrared variability
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arXiv
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| Autores principales: | , , , , , |
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| Formato: | Preprint |
| Publicado: |
2024
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| _version_ | 1866917673741320192 |
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| author | Green, K. Elmer, E. Maltby, D. T. Almaini, O. Merrifield, M. Hartley, W. G. |
| author_facet | Green, K. Elmer, E. Maltby, D. T. Almaini, O. Merrifield, M. Hartley, W. G. |
| contents | In this work, we use 8 years of deep near-infrared imaging to select and study a new set of 601 active galaxies identified through long-term near-infrared (NIR) variability in the UKIDSS Ultra Deep Survey (UDS). These objects are compared to 710 X-ray bright AGN detected by the Chandra X-ray observatory. We show that infrared variability and X-ray emission select distinct sets of active galaxies, finding only a 37 per cent overlap of galaxies detected by both techniques and confirming NIR-variable AGN to be typically X-ray quiet. Examining the mass functions of the active galaxies shows that NIR variability detects AGN activity in galaxies over a significantly wider range of host stellar mass compared to X-ray detection. For example, at z $\sim$ 1, variable AGN are identified among approximately 1 per cent of galaxies in a roughly flat distribution above the stellar mass completeness limit (> 10$^{9}$M$_{\odot}$), while X-ray detection primarily identifies AGN in galaxies of higher mass (> 10$^{10}$M$_{\odot}$). We conclude that long-term near-infrared variability provides an important new tool for obtaining more complete samples of AGN in deep survey fields. |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2405_14809 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Increasing AGN sample completeness using long-term near-infrared variability Green, K. Elmer, E. Maltby, D. T. Almaini, O. Merrifield, M. Hartley, W. G. Astrophysics of Galaxies In this work, we use 8 years of deep near-infrared imaging to select and study a new set of 601 active galaxies identified through long-term near-infrared (NIR) variability in the UKIDSS Ultra Deep Survey (UDS). These objects are compared to 710 X-ray bright AGN detected by the Chandra X-ray observatory. We show that infrared variability and X-ray emission select distinct sets of active galaxies, finding only a 37 per cent overlap of galaxies detected by both techniques and confirming NIR-variable AGN to be typically X-ray quiet. Examining the mass functions of the active galaxies shows that NIR variability detects AGN activity in galaxies over a significantly wider range of host stellar mass compared to X-ray detection. For example, at z $\sim$ 1, variable AGN are identified among approximately 1 per cent of galaxies in a roughly flat distribution above the stellar mass completeness limit (> 10$^{9}$M$_{\odot}$), while X-ray detection primarily identifies AGN in galaxies of higher mass (> 10$^{10}$M$_{\odot}$). We conclude that long-term near-infrared variability provides an important new tool for obtaining more complete samples of AGN in deep survey fields. |
| title | Increasing AGN sample completeness using long-term near-infrared variability |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2405.14809 |