Interesting Clues to Detect Hidden Tidal Disruption Events in Active Galactic Nuclei

TL;DR

This paper investigates how Tidal Disruption Events (TDEs) influence long-term variability in Active Galactic Nuclei (AGN) to develop methods for detecting hidden TDEs in normal broad line AGN, especially those with larger black hole masses.

Contribution

The study introduces a novel approach combining theoretical TDE variability patterns with AGN intrinsic variability simulations to identify TDE signatures in AGN light curves.

Findings

More massive black holes (>10^7 M_sun) show stronger TDE effects on variability timescales.

Stronger TDE contributions result in significantly larger variability timescale ratios.

TDE effects are more detectable in AGN with shorter intrinsic variability timescales and larger black hole masses.

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 analyzed 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 $\tau_{TN}$ on $R_{TN}$, with $\tau_{TN}$ as variability timescale ratio of light curves with TDEs contributions to intrinsic light curves without TDEs contributions, and $R_{TN}$ as ratio of peak intensity of TDEs expected variability to the mean intensity of intrinsic AGN variability without TDEs contributions. Second, stronger TDEs contributions $R_{TN}$ can lead to $\tau_{TN}$ quite larger than 5. Third, for intrinsic AGN variability having longer variability timescales, TDEs contributions will lead $\tau_{TN}$ 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 timescales, in different epochs, especially in normal broad line AGN with shorter intrinsic variability timescales and with BH masses larger than $10^7{\rm M_\odot}$.