Can A Kinematically Hot and Thick Disk Form A Bar? : Role of Highly Spinning Dark Matter Halos

TL;DR

This study uses N-body simulations to show that a kinematically hot, thick galactic disk can form a bar when embedded in a highly spinning dark matter halo, challenging previous stability assumptions.

Contribution

It demonstrates that spinning dark matter halos can induce bar formation in hot, thick disks, which were previously considered stable, providing new insights into galaxy evolution at high redshift.

Findings

Spinning halos significantly enhance angular momentum transfer.

Bars form in hot, thick disks within spinning halos, contrary to classical stability predictions.

Existing bar formation criteria do not predict bar formation in spinning halo scenarios.

Abstract

Recent JWST observations claim the existence of a significant fraction of bars in the kinematically hotter and thicker disk at high redshift Universe. These observations challenge the current understanding of disk stability in galaxies similar to the Milky Way. The analytical work and N-body simulations suggest that the kinematically hot (dispersion-dominated) and thick disk are stable against bar formation. In this work, we perform the controlled N-body simulations of a kinematically hot and thick disk, which is residing in a non-rotating and spinning dark matter halo. We report that the disk, which is classically stable against bar instability in the live and non-rotating halo, leads to bar formation in a spinning halo environment. The spinning halo model is 8 times more efficient in transporting angular momentum from the disk to the halo compared to the non-spinning halo. We claim that Ostriker-Peebles and ELN bar formation criteria do not predict bar formation for both the non-roating and spinning halo. The recent criteria from Jang-Kim successfully predict the bar stability for the non-rotating halo model, but not for the spinning halo model. These results provide an important insight into the bar formation processes for thick and hot disks at high redshift.