paper

Increasing AGN sample completeness using long-term near-infrared variability

arXiv:2405.14809 · doi:10.1093/mnras/stae1322

Abstract

In this work, we use 8 years of deep near-infrared imaging to select and study a new set of 601 active galaxies identified through long-term near-infrared (NIR) variability in the UKIDSS Ultra Deep Survey (UDS). These objects are compared to 710 X-ray bright AGN detected by the Chandra X-ray observatory. We show that infrared variability and X-ray emission select distinct sets of active galaxies, finding only a 37 per cent overlap of galaxies detected by both techniques and confirming NIR-variable AGN to be typically X-ray quiet. Examining the mass functions of the active galaxies shows that NIR variability detects AGN activity in galaxies over a significantly wider range of host stellar mass compared to X-ray detection. For example, at z 1, variable AGN are identified among approximately 1 per cent of galaxies in a roughly flat distribution above the stellar mass completeness limit (> 10M), while X-ray detection primarily identifies AGN in galaxies of higher mass (> 10M). We conclude that long-term near-infrared variability provides an important new tool for obtaining more complete samples of AGN in deep survey fields.

Accepted for publication in MNRAS. 12 pages, 11 figures

References in corpus (10)

Increasing AGN sample completeness using long-term near-infrared variability · wovepaper