Large-Scale Stellar Age-Velocity Spiral Pattern in NGC 4030

TL;DR

This study reveals a large-scale spiral pattern in the velocity dispersion of NGC 4030, linking stellar kinematics with star formation and proposing a complex age-velocity relation influenced by multiple heating mechanisms.

Contribution

It uncovers a grand design spiral pattern in stellar velocity dispersion and analyzes the age-velocity relation, offering new insights into disk heating processes in late-type galaxies.

Findings

Detection of a spiral pattern in velocity dispersion map.

Correlation between low velocity dispersion and star-forming regions.

Support for a complex age-velocity relation shaped by multiple heating mechanisms.

Abstract

The processes driving the formation and evolution of late-type galaxies (LTGs) continue to be a debated subject in extragalactic astronomy. Investigating stellar kinematics, especially when combined with age estimates, provides crucial insights into the formation and subsequent development of galactic discs. Post-processing of exceptionally high-quality Integral Field Spectroscopy (IFS) data of NGC 4030 acquired with the Multi Unit Spectroscopic Explorer (MUSE), clearly reveals a striking grand design spiral pattern in the velocity dispersion map not previously detected in other galaxies. This pattern spatially correlates with HII regions, suggesting that stars currently being born exhibit lower velocity dispersion as compared to surrounding areas where star formation (SF) is less active. We examine the age-velocity relation (AVR) and propose that its configuration might be shaped by a combination of heating mechanisms, seemingly consistent with findings from recent high-resolution cosmological zoom-in simulations. The complex structure of the uncovered AVR of NGC 4030 support the hypothesis that stellar populations initially inherit the velocity dispersion {\sigma} of the progenitor cold molecular gas, which depends on formation time and galactocentric distance, subsequently experiencing kinematic heating by cumulative gravitational interactions during their lifetime. While advancing our understanding of the AVR, these findings offer a new framework for investigating disk heating mechanisms, and their role in the evolution of galactic disks.