Bars driven by the Cosmology in stellar-gaseous disks

TL;DR

This study investigates how cosmology influences the formation and evolution of stellar bars in gaseous disks within dark matter halos, revealing that cosmology can produce bars even in gas-rich, dark matter-dominated disks, with star formation affecting bar strength.

Contribution

First analysis of bar growth in stellar-gaseous disks within a fully cosmological context, highlighting the role of gas fraction, star formation, and dark matter dominance.

Findings

Bars in dark matter-dominated disks persist to redshift zero.

High gas fractions can destroy bars in massive disks when star formation is off.

Star formation enhances bar strength and has mild effects on ellipticity.

Abstract

We present the first attempt to analyse the growth of the bar instability in stellar-gaseous disks evolving in a fully consistent cosmological scenario. We explored the role of the cosmology on pure stellar disks with different mass embedded in a cosmological dark matter halo. We deepened such a study by analysing the impact of different gas fractions and of the star formation onset. We found that in all these cases, the stellar bar arising inside the less massive disks, i.e., dark matter (DM)-dominated disks, is still living at redshift zero even if the gas fraction exceeds half of the disk mass. Such a bar is a genuine product of the cosmology. However, in the most massive disks there is a threshold value for their gas percentage and lower limit for the central gas concentration able to destroy the bar when the star formation rate is switched off. On the other hand in the simulations with star formation the central mass concentration of gas and of the new stars has a mild action on the ellipticity of the bar but is not able to destroy it; at z=0 the stellar bar strength is enhanced by the star formation. Even if our results qualitatively agree with the classical ones, i.e. with criteria concerning bar instability derived outside the cosmological framework, the same criteria cannot be validated for the DM-dominated disks.