Quantifying the unwinding due to ram pressure stripping in simulated galaxies

TL;DR

This paper investigates how ram pressure stripping causes unwinding of spiral arms in galaxies, using simulations to measure asymmetries in gas and stars, which can aid in observational classification.

Contribution

It provides a quantitative analysis of unwinding signatures in simulated galaxies, highlighting differences between gas and stellar components during ram pressure stripping.

Findings

Asymmetries are more prominent in gas than stars.

Unwinding amplitude increases over time.

Spiral arms extend further and are more unwound in gas.

Abstract

Galaxies moving through the gas of the intracluster medium (ICM) experience ram pressure stripping, which can leave behind a gas tail. When a disk galaxy receives the wind edge-on, however, the characteristic signature is not a typical jellyfish tail, but rather an unwinding of the spiral arms. We aim to quantify such asymmetries both in the gas and in the stellar component of a simulated galaxy. To this end, we simulate a gas-rich star-forming spiral galaxy moving through a self-consistent ICM gas. The amplitude and location of the asymmetries were measured via Fourier decomposition. We found that the asymmetry is much more evident in the gas component, but it is also measurable in the stars. The amplitude tends to increase with time and the asymmetry radius migrates inwards. We found that, when considering the gas, the spiral arms extend much further and are more unwound than the corresponding stellar arms. Characterizing the unwinding via simulations should help inform the observational criteria used to classify ram pressure stripped galaxies, as opposed to asymmetries induced by other mechanisms.