Interesting clues to detect hidden tidal disruption events in active galactic nuclei

ABSTRACT In the manuscript, effects of tidal disruption events (TDEs) are estimated on long-term AGN variability, to provide interesting clues to detect probable hidden TDEs in normal broad line AGN with apparent intrinsic variability which overwhelm the TDEs expected variability features, after considering the unique TDEs expected variability patterns. Based on theoretical TDEs expected variability plus AGN intrinsic variability randomly simulated by Continuous AutoRegressive process, long-term variability properties with and without TDEs contributions are well analysed in AGN. Then, interesting effects of TDEs can be determined on long-term observed variability of AGN. First, more massive BHs, especially masses larger than $10^7\, {\rm M_\odot }$, can lead to more sensitive and positive dependence of τTN on RTN, with τTN as variability time-scale ratio of light curves with TDEs contributions to intrinsic light curves without TDEs contributions, and RTN as ratio of peak intensity of TDEs expected variability to the mean intensity of intrinsic AGN variability without TDEs contributions. Secondly, stronger TDEs contributions RTN can lead to τTN quite larger than 5. Thirdly, for intrinsic AGN variability having longer variability time-scales, TDEs contributions will lead τTN to be increased more slowly. The results actually provide an interesting forward-looking method to detect probable hidden TDEs in normal broad-line AGN, due to quite different variability properties, especially different DRW/CAR process expected variability time-scales, in different epochs, especially in normal broad line AGN with shorter intrinsic variability time-scales and with BH masses larger than $10^7\, {\rm M_\odot }$.