Complexity and Multifractal Variability in Multi-Band Emission of Seyfert AGN

TL;DR

This study applies multifractal and information-theoretic analysis to multi-band light curves of four Seyfert AGNs, revealing complex variability patterns and persistent correlations across wavelengths.

Contribution

It introduces the combined use of MFDMA and Fisher-Shannon analysis to diagnose physical mechanisms behind AGN variability.

Findings

Revealed persistent correlations in AGN light curves.

Identified distinct variability patterns across energy bands.

Characterized stochasticity and structural complexity in emission processes.

Abstract

Active galactic nuclei (AGNs) exhibit complex variability across multiple wavelengths, reflecting diverse physical processes near their central engines. This work investigates the temporal variability of four AGNs Mrk~509, NGC~5548, NGC~4151, and NGC~4593 using multifractal detrended moving average (MFDMA) analysis and Fisher-Shannon information plane applied to their X-ray, ultraviolet, and optical light curves. These methods quantify the scaling behavior and complexity of the variability, revealing persistent correlations and distinct variability patterns across energy bands. The Fisher-Shannon analysis further characterizes the degree of stochasticity and structural complexity in the emission processes. Our findings support the interpretation that multifractal and information-theoretic measures provide effective diagnostics of the physical mechanisms driving AGN variability. This study demonstrates the utility of advanced time series techniques as effective diagnostics of AGN variability mechanisms.