Disc asymmetry characterisation in JWST-observed galaxies at 1 < z < 4

TL;DR

This paper introduces a Fourier-Laguerre based method to quantify disc galaxy asymmetry, revealing dependencies on wavelength and mass, and providing a new tool for morphological analysis in high-redshift galaxies.

Contribution

The paper presents a novel Fourier-Laguerre technique for measuring galaxy asymmetry, demonstrating its effectiveness over traditional methods and applying it to JWST and HST data.

Findings

Higher asymmetry at shorter wavelengths due to star-forming regions.

Lower mass galaxies exhibit higher asymmetry.

No clear correlation between asymmetry and redshift.

Abstract

We present a novel technique using Fourier series and Laguerre polynomials to represent morphological features of disc galaxies. To demonstrate the utility of this technique, we study the evolution of disc asymmetry in a sample of disc galaxies drawn from the Extended Groth Strip and imaged by the JWST Cosmic Evolution Early Release Science Survey as well as archival HST observations. We measure disc asymmetry as the amplitude of the of the m = 1 Fourier harmonic for galaxies within redshift ranges of 1 < z < 4 relative to the amplitude of m = 0 harmonic. We show that when viewed in shorter rest frame wavelengths, disc galaxies have a higher asymmetry as the flux is dominated by star forming regions. We find generally low asymmetry at rest frame infrared wavelengths, where our metric tracks asymmetry in morphological features such as bars and spiral arms. We show that higher mass galaxies have lower asymmetry and vice versa. Higher asymmetry in lower mass galaxies comes from lower mass galaxies (typically) having higher star formation rates. We measure the relation between disc galaxy asymmetry and redshift and find no conclusive relationship between them. We demonstrate the utility of the Fourier-Laguerre technique for recovering physically informative asymmetry measurements as compared to rotational asymmetry measurements. We also release the software pipeline and quantitative analysis for each galaxy.