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Lookup NU author(s): Dr Vicky FawcettORCiD
This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0).
© 2025. The Author(s). Published by the American Astronomical Society. We present the identification of changing-look active galactic nuclei (CL-AGNs) from the Dark Energy Spectroscopic Instrument First Data Release and Sloan Digital Sky Survey Data Release 16 at z ≤ 0.9. To confirm the CL-AGNs, we utilize spectral flux calibration assessment via an [O iii]-based calibration, pseudophotometry examination, and visual inspection. This rigorous selection process allows us to compile a statistical catalog of 561 CL-AGNs, encompassing 527 Hβ, 149 Hα, and 129 Mg ii CL behaviors. In this sample, we find (1) a 283:278 ratio of turn-on to turn-off CL-AGNs. (2) The median Eddington ratio for CL-AGNs in the dim state is approximately λEdd ∼ 0.01. (3) A strong correlation between the change in the luminosity of the broad emission lines (BELs) and variation in the continuum luminosity, with Mg ii and Hβ displaying similar responses during CL phases. (4) The Baldwin-Phillips-Terlevich diagram for CL-AGNs shows no statistical difference from the general AGN catalog. (5) Five CL-AGNs are associated with asymmetrical mid-infrared flares, possibly linked to tidal disruption events. Given the large CL-AGN sample and the stochastic sampling of spectra, we propose that some CL phenomena are inherently due to typical AGN variability during low accretion rates, particularly for CL phenomenon only occurring on one BEL. Finally, we introduce a monotonically dimming CL phase for objects characterized by a gradual decline over decades in the light curve and the complete disappearance of entire BELs in faint spectra, indicative of a real transition in the accretion disk.
Author(s): Guo W-J, Zou H, Greenwell CL, Alexander DM, Fawcett VA, Pan Z, Siudek M, Aguilar JN, Ahlen S, Brooks D, Claybaugh T, Dawson K, de la Macorra A, Doel P, Font-Ribera A, Gaztanaga E, Gontcho A Gontcho S, Gutierrez G, Kehoe R, Kisner T, Landriau M, Le Guillou L, Manera M, Meisner A, Miquel R, Moustakas J, Prada F, Rossi G, Sanchez E, Schubnell M, Sprayberry D, Sui J, Tarle G, Weaver BA, Xiao Y-A, Zou S
Publication type: Article
Publication status: Published
Journal: Astrophysical Journal Supplement Series
Year: 2025
Volume: 278
Issue: 1
Online publication date: 06/05/2025
Acceptance date: 01/03/2025
Date deposited: 18/09/2025
ISSN (print): 0067-0049
ISSN (electronic): 1538-4365
Publisher: American Astronomical Society
URL: https://doi.org/10.3847/1538-4365/adc124
DOI: 10.3847/1538-4365/adc124
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