Neutral atomic and molecular gas dynamics in the nearby spiral galaxies NGC 1512, NGC 4535, and NGC 7496

TL;DR

This study analyzes the dynamics of atomic and molecular gas in three nearby spiral galaxies using new MeerKAT-HI and ALMA CO observations, aiming to improve understanding of galactic evolution and star formation.

Contribution

It introduces a methodology combining HI and CO data to accurately determine galaxy orientations and dynamics, enhancing analysis of galactic gas behavior.

Findings

Successful application of combined HI and CO analysis for galaxy orientation

Establishment of a robust methodology for galaxy dynamics characterization

Preparation for high-resolution HI studies in the PHANGS sample

Abstract

Neutral atomic gas (HI) effectively traces galactic dynamics across mid to large galactocentric radii. However, its limitations in observing small-scale changes within the central few kiloparsecs, coupled with the often observed HI deficit in galactic centers, necessitates using molecular gas emission as a preferred tracer in these regions. Understanding the dynamics of both neutral atomic and molecular gas is crucial for a more complete understanding of how galaxies evolve, funnel gas from the outer disk into their central parts, and eventually form stars. In this work we aim to quantify the dynamics of both, the neutral atomic and molecular gas, in the nearby spiral galaxies NGC 1512, NGC 4535, and NGC 7496 using new MeerKAT-HI observations together with ALMA CO (2-1) observations from the PHANGS collaboration. We use the analysis tool 3D-Barolo to fit tilted ring models to the HI and CO observations. A combined approach of using the HI to constrain the true disk orientation parameters before applying these to the CO datasets is tested. This paper sets expectations for the results of the upcoming high-resolution HI coverage of many galaxies in the PHANGS-ALMA sample using MeerKAT or VLA, to establish a robust methodology for characterizing galaxy orientations and deriving dynamics from combining new HI with existing CO data.