Changing-look Active Galactic Nuclei from the Dark Energy Spectroscopic Instrument. II. Statistical Properties from the First Data Release

Changing-look Active Galactic Nuclei from the Dark Energy Spectroscopic Instrument. II. Statistical Properties from the First Data Release

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 cali...

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Main Authors: Wei-Jian Guo, Hu Zou, Claire L. Greenwell, David M. Alexander, Victoria A. Fawcett, Zhiwei Pan, Małgorzata Siudek, Jessica Nicole Aguilar, Steven Ahlen, David Brooks, Todd Claybaugh, Kyle Dawson, Axel de la Macorra, Peter Doel, Andreu Font-Ribera, Enrique Gaztañaga, Satya Gontcho A Gontcho, Gaston Gutierrez, Robert Kehoe, Theodore Kisner, Martin Landriau, Laurent Le Guillou, Marc Manera, Aaron Meisner, Ramon Miquel, John Moustakas, Francisco Prada, Graziano Rossi, Eusebio Sanchez, Michael Schubnell, David Sprayberry, Jipeng Sui, Gregory Tarlé, Benjamin Alan Weaver, Yun-Ao Xiao, Siwei Zou
Format: Article
Language:English
Published: IOP Publishing 2025-01-01
Series:The Astrophysical Journal Supplement Series
Subjects:
Active galactic nuclei
Active galaxies
Accretion
Supermassive black holes
Catalogs
Online Access:https://doi.org/10.3847/1538-4365/adc124
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Summary: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 H β , 149 H α , 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 λ _Edd  ∼ 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 H β 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.
ISSN:0067-0049

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