Gaseous Flows in Galaxies

TL;DR

This paper explores the role of gas in galaxy dynamics, focusing on how gaseous flows influence angular momentum transfer, bar evolution, and central activity in spiral galaxies.

Contribution

It provides a detailed analysis of gaseous flow mechanisms and their impact on galaxy evolution, highlighting the interplay between gas dynamics and structural features.

Findings

Gas triggers gravitational instabilities in spiral galaxies.

Strong bars are short-lived in the presence of gas.

Gas inflows can fuel nuclear starbursts and active nuclei.

Abstract

The gas component plays a major role in the dynamics of spiral galaxies, because of its dissipative character, and its ability to exchange angular momentum with stars in the disk. Due to its small velocity dispersion, it triggers gravitational instabilities, and the corresponding non-axisymmetric patterns produce gravity torques, which mediate these angular momentum exchanges. When a srong bar pattern develops with the same pattern speed all over the disk, only gas inside corotation can flow towards the center. But strong bars are not long lived in presence of gas, and multiple-speed spiral patterns can develop between bar phases, and help the galaxy to accrete external gas flowing from cosmic filaments. The gas is then intermittently driven to the galaxy center, to form nuclear starbursts and fuel an active nucleus. The various time-scales of these gaseous flows are described.