Active Galactic Nuclei in a Mid-Infrared Selected Galaxy Sample at z>0.13: [Ne V]3426 Line Emission as a Benchmark
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| Format: | Preprint |
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2024
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| _version_ | 1866929202113019904 |
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| author | Li, Zi-Jian Dai, Y. Sophia Huang, Jia-Sheng Wuyts, Stijn Cao, Tian-Wen |
| author_facet | Li, Zi-Jian Dai, Y. Sophia Huang, Jia-Sheng Wuyts, Stijn Cao, Tian-Wen |
| contents | We present a 24 um-selected spectroscopic sample z > 0.13 (median z = 0.41) in the Lockman Hole field, consisting of 4035 spectra. Our aim is to identify AGNs and determine their fraction in this mid-infrared selected sample. In this work, we use the [Ne V]3426 emission line to spectroscopically identify AGNs. Combined with broad-line Type I AGNs selected in our previous study, our sample consists of 887 (22%) spectroscopically confirmed AGNs. We perform a stacking analysis on the remaining spectra, and find that in various MIR-wedge-selected AGN candidates, the stacked spectra still show significant [Ne V]3426 emission, In contrast, no clear [Ne V]3426 signal is detected in non-AGN candidates falling outside the wedges. Assuming a range of AGN mid-IR SED slope of 0.3< alpha <0.7, and an average star-forming relation derived from 65 star-forming templates, we develop a robust method to separate the AGN and star-forming contributions to the mid-IR SEDs using the rest-frame L12 /L1.6 vs L4.5 /L1.6 diagram. We separate the objects into bins of L12 , and find that AGN fraction increases with increasing L12. We also find that the stacked [Ne V]3426 strength scales with L12 . The pure AGN luminosity at 12 um exhibits a positive correlation with the star formation rates, indicating possible co-evolution and common gas supply between the AGN and their host galaxies. Varying population properties across the redshift range explored contribute to the observed correlation. |
| format | Preprint |
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arxiv_https___arxiv_org_abs_2401_03416 |
| institution | arXiv |
| publishDate | 2024 |
| record_format | arxiv |
| spellingShingle | Active Galactic Nuclei in a Mid-Infrared Selected Galaxy Sample at z>0.13: [Ne V]3426 Line Emission as a Benchmark Li, Zi-Jian Dai, Y. Sophia Huang, Jia-Sheng Wuyts, Stijn Cao, Tian-Wen Astrophysics of Galaxies We present a 24 um-selected spectroscopic sample z > 0.13 (median z = 0.41) in the Lockman Hole field, consisting of 4035 spectra. Our aim is to identify AGNs and determine their fraction in this mid-infrared selected sample. In this work, we use the [Ne V]3426 emission line to spectroscopically identify AGNs. Combined with broad-line Type I AGNs selected in our previous study, our sample consists of 887 (22%) spectroscopically confirmed AGNs. We perform a stacking analysis on the remaining spectra, and find that in various MIR-wedge-selected AGN candidates, the stacked spectra still show significant [Ne V]3426 emission, In contrast, no clear [Ne V]3426 signal is detected in non-AGN candidates falling outside the wedges. Assuming a range of AGN mid-IR SED slope of 0.3< alpha <0.7, and an average star-forming relation derived from 65 star-forming templates, we develop a robust method to separate the AGN and star-forming contributions to the mid-IR SEDs using the rest-frame L12 /L1.6 vs L4.5 /L1.6 diagram. We separate the objects into bins of L12 , and find that AGN fraction increases with increasing L12. We also find that the stacked [Ne V]3426 strength scales with L12 . The pure AGN luminosity at 12 um exhibits a positive correlation with the star formation rates, indicating possible co-evolution and common gas supply between the AGN and their host galaxies. Varying population properties across the redshift range explored contribute to the observed correlation. |
| title | Active Galactic Nuclei in a Mid-Infrared Selected Galaxy Sample at z>0.13: [Ne V]3426 Line Emission as a Benchmark |
| topic | Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2401.03416 |