Analysis of the structural complexity of Crab Nebula observed at radio frequency using a multifractal approach

TL;DR

This study applies multifractal analysis to radio images of the Crab Nebula, revealing its complex, heterogeneous structure and long-range correlations, offering new insights into its morphology from a complexity science perspective.

Contribution

It introduces a systematic multifractal analysis of the Crab Nebula's radio data, demonstrating the multifractal nature and heterogeneity of its structure, which was not previously characterized in this way.

Findings

Radio data exhibit long-range correlations following a power-law.

The nebula's structure is multifractal and highly heterogeneous.

Multifractality arises from long-range correlations, not non-Gaussianity.

Abstract

The Crab Nebula is an astrophysical system that exhibits complex morphological patterns at different observing frequencies. We carry out a systematic investigation of the structural complexity of the nebula using publicly available imaging data at radio frequency. For the analysis, we use the well-known multifractal detrended fluctuation analysis in two dimensions. We find that radio data exhibit long-range correlations, as expected from the underlying physics of the supernova explosion and evolution. The correlations follow a power-law scaling with length scales. The structural complexity is found to be multifractal in nature, as evidenced by the dependence of the generalized Hurst exponent on the order of the moments of the detrended fluctuation function. By repeating the analysis on shuffled data, we further probe the origin of the multifractality in the radio imaging data. For the radio data, we find that the probability density function is close to a Gaussian form. Hence, the multifractal behavior is due to the differing nature of long-range correlations of the large and small detrended fluctuation field values. We investigate the multifractal parameters across different partitions of the radio image and find that the structures across the image are highly heterogeneous, making the Crab Nebula a structurally complex astrophysical system. Our analysis thus provides a fresh perspective on the morphology of the Crab Nebula from a complexity science viewpoint.