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

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

doi:10.1093/mnras/staa381

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

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

School of Physics and Astronomy

Research output: Contribution to journal › Article › peer-review

Abstract

We present the first attempt to select AGN using long-term NIR variability. By analysing the K-band light curves of all the galaxies in the UKIDSS Ultra Deep Survey, the deepest NIR survey over ~1 sq degree, 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 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.

Original language	English
Pages (from-to)	3026-3035
Number of pages	10
Journal	Monthly Notices of the Royal Astronomical Society
Volume	493
Issue number	2
Early online date	11 Feb 2020
DOIs	https://doi.org/10.1093/mnras/staa381
Publication status	Published - 1 Apr 2020

Keywords

astro-ph.GA

Access to Document

10.1093/mnras/staa381

Lawrence - 2002.02468Accepted author manuscript, 1.97 MB

https://arxiv.org/abs/2002.02468

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

abstract = " We present the first attempt to select AGN using long-term NIR variability. By analysing the K-band light curves of all the galaxies in the UKIDSS Ultra Deep Survey, the deepest NIR survey over ~1 sq degree, 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 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. ",

keywords = "astro-ph.GA",

author = "E. Elmer and O. Almaini and M. Merrifield and Hartley, {W. G.} and Maltby, {D. T.} and A. Lawrence and I. Botti and P. Hirst",

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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.

In: Monthly Notices of the Royal Astronomical Society , Vol. 493, No. 2, 01.04.2020, p. 3026-3035.

Research output: Contribution to journal › Article › peer-review

TY - JOUR

T1 - Long-term NIR Variability in the UKIDSS Ultra Deep Survey

T2 - a new probe of AGN activity at high redshift

AU - Elmer, E.

AU - Almaini, O.

AU - Merrifield, M.

AU - Hartley, W. G.

AU - Maltby, D. T.

AU - Lawrence, A.

AU - Botti, I.

AU - Hirst, P.

N1 - 12 pages, 18 figures, accepted for publication in MNRAS

PY - 2020/4/1

Y1 - 2020/4/1

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AB - We present the first attempt to select AGN using long-term NIR variability. By analysing the K-band light curves of all the galaxies in the UKIDSS Ultra Deep Survey, the deepest NIR survey over ~1 sq degree, 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 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.

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