Galactic disc warps from $z = 2.5$ to modern epoch: ruling out observational effects

TL;DR

This study analyzes the evolution of galactic disc warps from redshift 2.5 to the present, finding that warps were more common in the past, likely due to higher merger and interaction rates, and rules out observational biases.

Contribution

It provides the first large-scale analysis of warp prevalence over cosmic time using HST and JWST data, demonstrating genuine evolutionary trends.

Findings

Warped galaxies were more prevalent at higher redshifts.

The observed trend is not due to observational biases.

Galaxy interactions likely drive warp formation in the past.

Abstract

A significant fraction of galaxies show warps in their discs, usually noticeable at its periphery. The exact origin of this phenomenon is not fully established, although multiple warp formation mechanisms are proposed. In this study, we create a sample of more than 1000 distant ($z \lesssim 2.5$) edge-on galaxies imaged by HST and JWST. For these galaxies, we measurd characteristics of warps and finally analyse how their parameters and frequency change with time. We focus on our main result that galaxies with strong warps were more prevalent in the past compared to the modern epoch. We check how selection effects and varying image quality between objects in our sample could influence our results and conclude that varying fraction of warped galaxies is not caused by observational effects, but represents a genuine evolution. Such a trend may be consistent with mergers and interactions between galaxies being the primary mechanism of warp formation, as number density of galaxies decreases with time, implying higher rate of mergers and interactions in the past.