Towards a complete census of luminous Compton-thick active galactic nuclei in the Local Universe

Akylas, A.; Georgantopoulos, I.; Gandhi, P.; Boorman, P.; Greenwell, C. L.

Abstract

X-ray surveys provide the most efficient means for the detection of active galactic nuclei (AGNs). However, they do face difficulties in detecting the most heavily obscured Compton-thick AGNs. The BAT detector on board the Gehrels/Swift mission, operating in the very hard 14–195 keV band, has provided the largest samples of Compton-thick AGN in the Local Universe. However, even these flux-limited samples may miss the most obscured sources among the Compton-thick AGN population. A robust way to find these local sources is to systematically study volume-limited AGN samples detected in the IR or the optical part of the spectrum. Here, we utilise a local sample (< 100 Mpc) of mid-IR-selected AGNs, unbiased against obscuration, to determine the fraction of Compton-thick sources in the Local Universe. When available, we acquired X-ray spectral information for the sources in our sample from previously published studies. In addition, to maximise the X-ray spectral information for the sources in our sample, we analysed eleven unexplored XMM-Newton and NuSTAR observations, for the first time. In this way, we identified four new Compton-thick sources. Our results reveal an increased fraction of Compton-thick AGNs among the sources that have not been detected by BAT of 44%. Overall, we have estimated a 25–30% share of Compton-thick sources in the Local Universe among mid-IR-selected AGNs. We find no evidence for any evolution of the AGN Compton-thick fraction with luminosity.

Citation

Akylas, A., Georgantopoulos, I., Gandhi, P., Boorman, P., & Greenwell, C. L. (2024). Towards a complete census of luminous Compton-thick active galactic nuclei in the Local Universe. Astronomy & Astrophysics, 692, Article A250. https://doi.org/10.1051/0004-6361/202451906

• Journal Article Type: Article
• Acceptance Date: Oct 7, 2024
• Online Publication Date: Dec 19, 2024
• Publication Date: 2024-12
• Deposit Date: Jan 16, 2025
• Publicly Available Date: Jan 16, 2025
• Journal: Astronomy & Astrophysics
• Print ISSN: 0004-6361
• Electronic ISSN: 1432-0746
• Publisher: EDP Sciences
• Peer Reviewed: Peer Reviewed
• Volume: 692
• Article Number: A250
• DOI: https://doi.org/10.1051/0004-6361/202451906
• Public URL: https://durham-repository.worktribe.com/output/3337109