Multifractality Signatures in Quasars Time Series. I. 3C 273

TL;DR

This paper investigates the multifractal properties of flux variability in the quasar 3C 273 across multiple electromagnetic bands, revealing weak multifractality mainly due to non-linear correlations, with potential applications in quasar classification.

Contribution

It applies the MFDMA method to analyze multifractality in quasar time series across different bands, highlighting the origin and variability of multifractal signatures.

Findings

Weak multifractality observed in most bands except mm, UV, and X-ray.

Non-linear temporal correlations are the main source of multifractality.

Multifractal analysis can help classify quasars based on their fractal signatures.

Abstract

The presence of multifractality in a time series shows different correlations for different time scales as well as intermittent behaviour that cannot be captured by a single scaling exponent. The identification of a multifractal nature allows for a characterization of the dynamics and of the intermittency of the fluctuations in non-linear and complex systems. In this study, we search for a possible multifractal structure (multifractality signature) of the flux variability in the quasar 3C 273 time series for all electromagnetic wavebands at different observation points, and the origins for the observed multifractality. This study is intended to highlight how the scaling behaves across the different bands of the selected candidate which can be used as an additional new technique to group quasars based on the fractal signature observed in their time series and determine whether quasars are non-linear physical systems or not. The Multifractal Detrended Moving Average algorithm (MFDMA) has been used to study the scaling in non-linear, complex and dynamic systems. To achieve this goal, we applied the backward ({\theta} = 0) MFDMA method for one-dimensional signals. We observe weak multifractal (close to monofractal) behaviour in some of the time series of our candidate except in the mm, UV and X-ray bands. The non-linear temporal correlation is the main source of the observed multifractality in the time series whereas the heaviness of the distribution contributes less.