학술논문
Changing-look Active Galactic Nuclei from the Dark Energy Spectroscopic Instrument. I. Sample from the Early Data
Document Type
article
Author
Wei-Jian Guo; Hu Zou; Victoria A. Fawcett; Rebecca Canning; Stephanie Juneau; Tamara M. Davis; David M. Alexander; Linhua Jiang; Jessica Nicole Aguilar; Steven Ahlen; David Brooks; Todd Claybaugh; Axel de la Macorra; Peter Doel; Kevin Fanning; Jaime E. Forero-Romero; Satya Gontcho A Gontcho; Klaus Honscheid; Theodore Kisner; Anthony Kremin; Martin Landriau; Aaron Meisner; Ramon Miquel; John Moustakas; Jundan Nie; Zhiwei Pan; Claire Poppett; Francisco Prada; Mehdi Rezaie; Graziano Rossi; Małgorzata Siudek; Eusebio Sanchez; Michael Schubnell; Hee-Jong Seo; Jipeng Sui; Gregory Tarlé; Zhimin Zhou
Source
The Astrophysical Journal Supplement Series, Vol 270, Iss 2, p 26 (2024)
Subject
Language
English
ISSN
1538-4365
0067-0049
0067-0049
Abstract
Changing-look active galactic nuclei (CL AGNs) can be generally confirmed by the emergence (turn-on) or disappearance (turn-off) of broad emission lines (BELs), associated with a transient timescale (about 100 ∼ 5000 days) that is much shorter than predicted by traditional accretion disk models. We carry out a systematic CL AGN search by crossmatching the spectra coming from the Dark Energy Spectroscopic Instrument and the Sloan Digital Sky Survey. Following previous studies, we identify CL AGNs based on H α , H β , and Mg ii at z ≤ 0.75 and Mg ii , C iii ], and C iv at z > 0.75. We present 56 CL AGNs based on visual inspection and three selection criteria, including 2 H α , 34 H β , 9 Mg ii , 18 C iii ], and 1 C iv CL AGN. Eight cases show simultaneous appearances/disappearances of two BELs. We also present 44 CL AGN candidates with significant flux variation of BELs, but remaining strong broad components. In the confirmed CL AGNs, 10 cases show additional CL candidate features for different lines. In this paper, we find: (1) a 24:32 ratio of turn-on to turn-off CL AGNs; (2) an upper-limit transition timescale ranging from 330 to 5762 days in the rest frame; and (3) the majority of CL AGNs follow the bluer-when-brighter trend. Our results greatly increase the current CL census (∼30%) and would be conducive to exploring the underlying physical mechanism.