How does dark matter stabilize disc galaxies?

Abstract

The study presents a theoretical framework for understanding the role of dark matter on the stability of the galactic disc. We model the galaxy as a two-component system consisting of stars and gas in equilibrium with an external dark matter halo. We derive the equations governing the growth of perturbations and obtain a stability criterion that connects the potential of the dark matter halo and the gas fraction with the stability levels of the galaxy. We find that a two-component disc is more susceptible to the growth of gravitational instabilities than individual components, particularly as gas fractions increase. However, the external field, due to the dark matter halo, acts as a stabilizing agent and increases the net stability levels even in the presence of a cold gas component. We apply the stability criterion to models of the Milky Way, low surface brightness galaxies, and baryon-dominated cold rotating disc galaxies observed in the early universe. Our results show that the potential due to the dark matter halo plays a significant role in stabilizing nearby galaxies, such as the Milky Way, and low surface brightness galaxies, which would otherwise be prone to local gravitational instabilities. However, we find that the baryon-dominated cold disc galaxies observed in the early universe remain susceptible to the growth of local gravitational instabilities despite the stabilizing effect of the dark matter halo.

Accepted for publication in MNRAS

References in corpus (11)

• SPARC: Mass Models for 175 Disk Galaxies with Spitzer Photometry and Accurate Rotation Curves
• What is Driving the HI Velocity Dispersion?
• Strongly baryon-dominated disk galaxies at the peak of galaxy formation ten billion years ago
• Dynamical properties of z $\sim 4.5$ dusty star-forming galaxies and their connection with local early type galaxies
• Rotation Curves in z~1-2 Star-Forming Disks: Evidence for Cored Dark Matter Distributions
• Characterizing gravitational instability in turbulent multi-component galactic discs
• The effect of ISM turbulence on the gravitational instability of galactic discs
• Origin of low surface brightness galaxies: A dynamical study
• Molecular Clouds as Gravitational Instabilities in Rotating Disks: A Modified Stability Criterion
• Local gravitational instability of stratified rotating fluids: 3D criteria for gaseous discs
• Stability of galaxies across morphological sequence