Reduced spectra of CL-AGN candidates

We successfully confirm seven turn-on CL-AGNs among 12 candidates in this work. Compared with both the general AGN populations and the spectroscopically identified CL-AGN sample, these CL-AGNs show larger optical and MIR variations and k values. The extreme CM variabilities of these sources (with optical magnitude changes >0.9) occurred recently.

For four sources, flare-like brightening episodes were temporally associated with turn-on transitions within 3-7 years, suggesting that these flares may trace short-timescale accretion enhancement, central brightening, and broad-line region re-illumination. In addition, the estimated Eddington ratios for the confirmed CL-AGNs appear to cluster around a critical value of {lambda}_Edd_~0.01. The extreme CM variability serves as a highly efficient criterion for finding CL-AGNs.

The properties of the CL-AGNs thus found suggest that they may represent AGNs at a pivotal state, which likely occurs in CL transitions due to enhanced accretion activity, while the cause of the accretion activity, which was determined to have a timescale of several years in this work, remains to be investigated further.