Related papers: Discovering Changing-Look AGN in the 6dF Galaxy Su…
Changing-look Active Galactic Nuclei (CLAGN) are AGN that change type as their broad emission lines appear or disappear, which is usually accompanied by strong flux changes inn their blue featureless continuum. We search for Turn-On CLAGN…
Changing-look Active Galactic Nuclei (CL AGN) can be generally confirmed by the emergence (turn-on) or disappearance (turn-off) of broad emission lines, associated with a transient timescale (about $100\sim5000$ days) that is much shorter…
Changing-look active galactic nuclei (CLAGNs) are a unique population of AGNs that exhibit the appearance (turn-on) or disappearance (turn-off) of broad emission lines. This study aims to explore the intrinsic mechanisms of CLAGNs by…
Although more than 1000 optical changing-look active galactic nuclei (CLAGNs) have been reported to date, their physical origin remains unclear, and repeating CLAGNs (RCLAGNs) are still rare. Expanding the CLAGN sample, especially RCLAGNs,…
"Changing-look" active galactic nuclei (CL-AGNs) challenge our basic ideas about the physics of accretion flows and circumnuclear gas around supermassive black holes. Using first-year Sloan Digital Sky Survey V (SDSS-V) repeated…
We report the finding of four changing-look (CL) active galactic nuclei (AGN). We selected these sources due to their potential as interesting targets when considering their relatively-large optical flux variations and related mid-infrared…
Changing-look Active Galactic Nuclei (CL AGNs) exhibit drastic variations in broad emission lines (BELs), the mechanism of which remains unclear. Expanding the sample of CL AGNs is helpful to reveal the mechanism. This study aims to…
Changing-look (CL) Active Galactic Nuclei (AGNs), characterized by appearance/disappearance of broad emission lines in the span of a few years, present a challenge for the AGN unified model, whereby the Type 1 vs. Type 2 dichotomy results…
"Changing-look" active galactic nuclei (CL-AGNs) are a newly-discovered class of AGNs that show the appearance (or disappearance) of broad emission lines within a short time scale (months to years) and are often associated with the dramatic…
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 \leq 0.9. To confirm the CL-AGNs, we utilize…
This paper is the first in a series of preparing and analyzing spectral and other properties for a database of already discovered Changing-Look active galactic nuclei (CL AGNs). Here, we focus on the spectral fitting and analysis of broad…
The repeating changing-look active galactic nuclei (RCL AGNs) exhibit multiple appearances and disappearances of broad emission lines (BELs), whose underlying mechanism remains a puzzle. Expanding the sample of RCL AGNs is valuable for…
Low luminosity active galactic nuclei (LLAGN) probe accretion physics in the low Eddington regime and can provide additional clues about galaxy evolution. AGN variability is ubiquitous and thus provides a reliable tool for finding AGN. We…
The changing-look active galactic nucleus (CL-AGN), an extraordinary subpopulation of supermassive black holes, has attracted growing attention for understanding its nature. We present an analysis of the spectral properties of 203…
Changing-Look (CL) is a rare phenomenon of Active Galactic Nuclei (AGNs) that exhibit emerging or disappearing broad lines accompanied by continuum variations on astrophysically short timescales ($\lesssim$ 1 yr to a few decades). While…
The discovery of changing-look active galactic nuclei (CLAGNs) with the significant change of optical broad emission lines (optical CLAGNs) and/or strong variation of line-of-sight column densities (X-ray CLAGNs) challenges the…
Changing-look active galactic nuclei (CLAGNs) show the appearance and disappearance of broad emission lines in their UV/optical spectra on timescales of months to decades. Here, we investigate how CL transitions depend on several AGN…
The widely accepted active galactic nucleus (AGN) paradigm has been recently challenged by the discovery of the so-called ``changing-look'' (CL) phenomenon characterized by spectral-type transitions. By comparing the SDSS-V and SDSS DR16…
We here report a spectroscopic identification of two new changing-look AGNs (CL-AGNs): SDSS\,J104705.16+544405.8 and SDSS\,J120447.91+170256.8 both with a "turn-off" type transition from type 1 to type 1.8/1.9. The identification is arrived…
The Six-degree Field Galaxy Survey (6dFGS) is a spectroscopic redshift survey of the Southern hemisphere completed in 2006. While it provides 136,304 spectra of mostly low-redshift galaxies, a large and reliable catalogue of Active Galactic…