Long-term NIR Variability in the UKIDSS Ultra Deep Survey: a new probe of AGN activity at high redshift

Elmer, E.; Almaini, O.; Merrifield, M.; Hartley, W. G.; Maltby, D. T.; Lawrence, A.; Botti, I.; Hirst, P.

Abstract

We present the first attempt to select active galactic nuclei (AGN) using long-Term near-infrared (NIR) variability. By analysing the K-band light curves of all the galaxies in the UKIRT Infrared Deep Sky Survey (UKIDSS) Ultra Deep Survey, the deepest NIR survey over ∼1 deg2, we have isolated 393 variable AGN candidates. A comparison to other selection techniques shows that only half of the variable sources are also selected using either deep Chandra X-ray imaging or Infrared Array Camera (IRAC) colour selection, suggesting that using NIR variability can locate AGN that are missed by more standard selection techniques. In particular, we find that long-Term NIR variability identifies AGN at low luminosities and in host galaxies with low stellar masses, many of which appear relatively X-ray quiet.

Citation

Elmer, E., Almaini, O., Merrifield, M., Hartley, W. G., Maltby, D. T., Lawrence, A., …Hirst, P. (2020). Long-term NIR Variability in the UKIDSS Ultra Deep Survey: a new probe of AGN activity at high redshift. Monthly Notices of the Royal Astronomical Society, 493(2), 3026-3035. https://doi.org/10.1093/mnras/staa381

• Journal Article Type: Article
• Acceptance Date: Feb 6, 2020
• Online Publication Date: Feb 11, 2020
• Publication Date: Feb 11, 2020
• Deposit Date: Feb 13, 2020
• Publicly Available Date: Feb 13, 2020
• Journal: Monthly Notices of the Royal Astronomical Society
• Print ISSN: 0035-8711
• Electronic ISSN: 1365-2966
• Publisher: Oxford University Press
• Peer Reviewed: Peer Reviewed
• Volume: 493
• Issue: 2
• Pages: 3026-3035
• DOI: https://doi.org/10.1093/mnras/staa381
• Keywords: Space and Planetary Science; Astronomy and Astrophysics
• Public URL: https://nottingham-repository.worktribe.com/output/3956720
• Publisher URL: https://academic.oup.com/mnras/advance-article/doi/10.1093/mnras/staa381/5733174
• Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record E Elmer, O Almaini, M Merrifield, W G Hartley, D T Maltby, A Lawrence, I Botti, P Hirst, Long-term NIR Variability in the UKIDSS Ultra Deep Survey: a new probe of AGN activity at high redshift., Monthly Notices of the Royal Astronomical Society, , staa381 is available online at: https://doi.org/10.1093/mnras/staa381.