A Systematic Analysis of Stellar Populations in the Host Galaxies of Changing-look AGNs

"Changing-look" active galactic nuclei (CL-AGNs) are a newly-discovered class of AGNs that show the appearance (or disappearance) broad emission lines within short time scale (months to years) and often associated with dramatic change their continuum emissions. They provide us an unprecedented chance directly investigate host galaxy properties minimal contamination from luminous central engine during "turn-off" state, which is difficult for normal AGNs. In this work, first time, we systematically characterize stellar populations star formation histories (SFHs) galaxies 26 turn-off CL-AGNs using population synthesis code STARLIGHT. We find similar AGNs, excepts intermediate contribute more fraction. estimate velocity dispersions ($\rm \sigma_{\star}$) black hole masses M_{BH,vir}$) also follow overall $\rm M_{BH}-\sigma_{\star}$ relationship. confirm previous claim tend be biased towards lower Eddington ratio, extreme variabilities likely due intrinsic changes accretion rates. addition, recent formations (SF) have higher ratio. Compared studies, our analysis suggests there may correlation between CL-AGN CL phenomena.