ALMA/SCUBA-2 COSMOS Survey: Properties of X-Ray- and SED-selected Active Galactic Nuclei in Bright Submillimeter Galaxies

Uematsu, Ryosuke; Ueda, Yoshihiro; Alexander, David M.; Swinbank, A. M.; Smail, Ian; Andonie, Carolina; Chen, Chian-Chou; Dudzevičiūtė, Ugne; Ikarashi, Soh; Kohno, Kotaro; Matsuda, Yuichi; Puglisi, Annagrazia; Umehata, Hideki; Wang, Wei-Hao

Abstract

We investigate the properties of active galactic nuclei (AGNs) in the brightest submillimeter galaxies (SMGs) in the COSMOS field. We utilize the bright sample of the ALMA/SCUBA-2 COSMOS Survey (AS2COSMOS), which consists of 260 SMGs with S870 μm = 0.7–19.2 mJy at z = 0–6. We perform optical to millimeter spectral energy distribution (SED) modeling for the whole sample. We identify 24 AGN-host galaxies from the SEDs. Supplemented by 23 X-ray-detected AGNs (X-ray AGNs), we construct an overall sample of 40 AGN-host galaxies. The X-ray luminosity upper bounds indicate that the X-ray-undetected SED-identified AGNs are likely to be nearly Compton thick or have unusually suppressed X-ray emission. From visual classification, we identify 25−5+6 % of the SMGs without AGNs as major merger candidates. This fraction is almost consistent with the general galaxy population at z ∼ 2, suggesting that major mergers are not necessarily required for the enhanced star formation in SMGs. We also identify 47−15+16 % of the AGN hosts as major merger candidates, which is about twice as high as that in the SMGs without AGNs. This suggests that major mergers play a key role in triggering AGN activity in bright SMGs.

Citation

Uematsu, R., Ueda, Y., Alexander, D. M., Swinbank, A. M., Smail, I., Andonie, C., Chen, C.-C., Dudzevičiūtė, U., Ikarashi, S., Kohno, K., Matsuda, Y., Puglisi, A., Umehata, H., & Wang, W.-H. (2025). ALMA/SCUBA-2 COSMOS Survey: Properties of X-Ray- and SED-selected Active Galactic Nuclei in Bright Submillimeter Galaxies. The Astrophysical Journal, 979(2), Article 168. https://doi.org/10.3847/1538-4357/ad9f3b

• Journal Article Type: Article
• Acceptance Date: Dec 12, 2024
• Online Publication Date: Jan 24, 2025
• Publication Date: Feb 1, 2025
• Deposit Date: Feb 7, 2025
• Publicly Available Date: Feb 7, 2025
• Journal: The Astrophysical Journal
• Electronic ISSN: 1538-4357
• Peer Reviewed: Peer Reviewed
• Volume: 979
• Issue: 2
• Article Number: 168
• DOI: https://doi.org/10.3847/1538-4357/ad9f3b
• Keywords: X-ray active galactic nuclei, Submillimeter astronomy, Active galaxies, High-redshift galaxies
• Public URL: https://durham-repository.worktribe.com/output/3351851