Revisiting the Gas Dynamics of Henize 2-10: Possible Drivers of the Starburst

TL;DR

This study investigates the gas dynamics of Henize 2-10 using new radio observations to understand the possible causes of its starburst, challenging previous merger-based explanations and suggesting large-scale gas inflow as a trigger.

Contribution

The paper provides new VLA and archival CO data revealing complex gas dynamics, and offers a meta-analysis proposing gas inflow as a starburst trigger in Henize 2-10.

Findings

No HI tail detected, contradicting previous merger evidence.

HI is dynamically decoupled from CO features, indicating large-scale dynamical processes.

Large CO feature may be infalling gas triggering starburst activity.

Abstract

The triggers of starburst episodes are a key component to our understanding of the baryon cycle in galaxies. Galaxy mergers are a commonly suggested catalyst for starbursts, but once the galaxies coalesce into a single kinematically disturbed system, their merger history can be difficult to assess. This is particularly true for dwarf galaxies, which are expected to dominate the merger rate at all redshifts due to their large numbers. One such dwarf galaxy undergoing an enigmatic starburst episode is Henize 2-10, which appears to be isolated. Possible scenarios that might have caused the starburst episode include a previous merger or stochastic processes within the galaxy itself, such as self-regulation via feedback processes. We present new VLA 21-cm observations and unpublished archival CARMA CO data to investigate the dynamical state and star formation activity in the galaxy. We do not detect an HI tail consistent with the structure reported by Kobulnicky et al. (1995), which was suggested as evidence for a merger or interaction, but rather these new observations indicate an extended HI distribution. We also find that the HI appears dynamically decoupled from an extended CO feature (inferred to be a tidal tail in previous work), suggesting large-scale dynamical processes of some type are affecting the gas in this system. We provide a meta-analysis of available results to enhance our understanding of what might be triggering the starburst episode in Henize 2-10, and speculate that the large CO feature could be falling into the galaxy and potentially trigger starburst activity.