Physical properties of gas departing from circular rotation at 50 pc scales using the PHANGS-MUSE galaxies

TL;DR

This study investigates the physical properties of ionized gas involved in noncircular motions within disk galaxies at 50 parsec scales, revealing correlations between gas dynamics and physical conditions using advanced 3D kinematic modeling.

Contribution

The paper introduces a new 3D kinematic modeling tool applied to PHANGS-MUSE data, enabling detailed analysis of noncircular motions and their relation to gas properties in galaxies.

Findings

Ionized gas shows noncircular motions with amplitudes up to >20 km/s.

Velocity dispersion correlates with noncircular motion amplitude.

Noncircular motions vary across galaxy regions, linked to physical gas properties.

Abstract

Noncircular motions have been observed across various spatial scales in disk galaxies, yet the physical properties of the gas involved in these motions remain poorly constrained. Using data from 19 galaxies from the PHANGS-MUSE sample, we investigated the prevalence of noncircular flows at spatial resolutions of tens of parsecs. We developed a new tool for 3D kinematic modelling of data cubes and applied it to the PHANGS-MUSE H$\alpha$ spectral lines to recover the underlying circular, noncircular motions, as well as the intrinsic velocity dispersion in these objects. The PHANGS-MUSE galaxies exhibit rotation supported disks with $V_\mathrm{rot}/\sigma_\mathrm{intrin}$ ratios $\gtrsim$ 5. Our analysis revealed ionized gas exhibiting noncircular motions at different amplitudes, with low velocity amplitudes of about $5\mathrm{km\,s^{-1}}$ associated with the axisymmetric rotation component, deviations of $\sim10\mathrm{km\,s^{-1}}$ primarily linked to interarm and spiral arms, and larger deviations ($>20 \mathrm{km\,s^{-1}}$), found in the central and bar regions. We found that the velocity dispersion and the strength of ionization correlate with the amplitude of noncircular motions, suggesting that the underlying dynamics of the warm gas are closely tied to its physical properties.