Unveiling Obscured Accretion in the Local Universe
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arXiv
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| Autores principales: | , , , , , , , , , , , |
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| Formato: | Preprint |
| Publicado: |
2025
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| _version_ | 1866914057247784960 |
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| author | Pal, Indrani Marchesi, Stefano Silver, Ross Ajello, Marco Gianolli, Vittoria Torres-Albà, Núria Cox, Isaiah Zhao, Xiurui Sengupta, Dhrubojyoti Banerjee, Anuvab Imam, Kouser Pizzetti, Andrealuna |
| author_facet | Pal, Indrani Marchesi, Stefano Silver, Ross Ajello, Marco Gianolli, Vittoria Torres-Albà, Núria Cox, Isaiah Zhao, Xiurui Sengupta, Dhrubojyoti Banerjee, Anuvab Imam, Kouser Pizzetti, Andrealuna |
| contents | Heavily obscured Active Galactic Nuclei (AGN), especially Compton-thick sources with line-of-sight column density ($N_{\rm H,los}$) $>$ 10$^{24}$ cm$^{-2}$, are critical to understanding supermassive black hole (SMBH) growth and the origin of the Cosmic X-ray Background (CXB). However, their observed fraction remains significantly below model predictions, due to strong absorption bias, even in the hard X-ray (i.e., above 10 keV) band. We analyze a sample of 26 nearby ($z < 0.1$) AGN from the Swift-BAT 150-month catalog, selected via mid-IR to X-ray diagnostics and observed with NuSTAR and soft X-ray telescopes (Xmm-Newton, Chandra, or Swift-xrt). Using self-consistent torus models (MyTorus, Borus02, and UXCLUMPY), we aim to constrain $N_{\rm H,los}$, the average torus column density, and other geometrical parameters of the obscuring medium. A comparative analysis among the three torus models showed that while estimates of $N_{\rm{H,los}}$ were generally in agreement, Borus02 tended to classify a slightly larger number of sources as Compton-thick AGN (CT-AGN). Building on this comparison, we benchmark two prediction schemes -- a mid-IR/X-ray relation and a machine-learning model -- against our broadband best-fit $N_{\rm H,los}$ measurements to assess which approach more effectively bridges the gap between predicted and measured obscuration, finding that while the former works effectively in the heavily obscured region (log$\rm{N_H} \gtrsim$ 23.5 $\rm{cm^{-2}}$), the latter provides improved accuracy, particularly for Compton-thin to moderately thick regimes (log$\rm{N_H} \lesssim$ 23.5 $\rm{cm^{-2}}$). |
| format | Preprint |
| id |
arxiv_https___arxiv_org_abs_2509_21532 |
| institution | arXiv |
| publishDate | 2025 |
| record_format | arxiv |
| spellingShingle | Unveiling Obscured Accretion in the Local Universe Pal, Indrani Marchesi, Stefano Silver, Ross Ajello, Marco Gianolli, Vittoria Torres-Albà, Núria Cox, Isaiah Zhao, Xiurui Sengupta, Dhrubojyoti Banerjee, Anuvab Imam, Kouser Pizzetti, Andrealuna High Energy Astrophysical Phenomena Astrophysics of Galaxies Heavily obscured Active Galactic Nuclei (AGN), especially Compton-thick sources with line-of-sight column density ($N_{\rm H,los}$) $>$ 10$^{24}$ cm$^{-2}$, are critical to understanding supermassive black hole (SMBH) growth and the origin of the Cosmic X-ray Background (CXB). However, their observed fraction remains significantly below model predictions, due to strong absorption bias, even in the hard X-ray (i.e., above 10 keV) band. We analyze a sample of 26 nearby ($z < 0.1$) AGN from the Swift-BAT 150-month catalog, selected via mid-IR to X-ray diagnostics and observed with NuSTAR and soft X-ray telescopes (Xmm-Newton, Chandra, or Swift-xrt). Using self-consistent torus models (MyTorus, Borus02, and UXCLUMPY), we aim to constrain $N_{\rm H,los}$, the average torus column density, and other geometrical parameters of the obscuring medium. A comparative analysis among the three torus models showed that while estimates of $N_{\rm{H,los}}$ were generally in agreement, Borus02 tended to classify a slightly larger number of sources as Compton-thick AGN (CT-AGN). Building on this comparison, we benchmark two prediction schemes -- a mid-IR/X-ray relation and a machine-learning model -- against our broadband best-fit $N_{\rm H,los}$ measurements to assess which approach more effectively bridges the gap between predicted and measured obscuration, finding that while the former works effectively in the heavily obscured region (log$\rm{N_H} \gtrsim$ 23.5 $\rm{cm^{-2}}$), the latter provides improved accuracy, particularly for Compton-thin to moderately thick regimes (log$\rm{N_H} \lesssim$ 23.5 $\rm{cm^{-2}}$). |
| title | Unveiling Obscured Accretion in the Local Universe |
| topic | High Energy Astrophysical Phenomena Astrophysics of Galaxies |
| url | https://arxiv.org/abs/2509.21532 |