Shockingly Effective: Cluster Winds as Engines of Feedback in Starburst Galaxy VV 114

TL;DR

This study uses high-resolution spectroscopy and imaging to demonstrate that star cluster winds and supernovae drive galactic superwinds in the starburst galaxy VV 114, revealing the mechanisms of feedback in galaxy evolution.

Contribution

It provides direct observational evidence linking star cluster winds to galactic-scale feedback and superwinds in a local starburst galaxy, supported by detailed spectral and imaging analysis.

Findings

Star cluster winds account for at least 70% of shock luminosity.

Shock ionization is anticorrelated with star cluster density.

The superwind energy matches the kinetic power of cluster winds.

Abstract

We present high-resolution Keck Cosmic Web Imager (KCWI) and MUSE IFU spectroscopy of VV 114, a local infrared-luminous merger undergoing a vigorous starburst and showing evidence of galactic-scale feedback. The high-resolution data allow for spectral deblending of the optical emission lines and reveal a broad emission line component ($\sigma_{\rm{broad}} \sim$~100--300 km s$^{-1}$) with line ratios and kinematics consistent with a mixture of ionization by stars and radiative shocks. The shock fraction (percent ionization due to shocks) in the high velocity gas is anticorrelated with projected surface number density of resolved star clusters, and we find radial density profiles around clusters are well fit by models of adiabatically expanding cluster winds driven by massive stellar winds and supernovae (SNe). The total kinetic power estimated from the cluster wind models matches the wind+SNe mechanical energy deposition rate estimated from the soft band X-ray luminosity, indicating that at least 70\% of the shock luminosity in the galaxy is driven by the star clusters. \emph{Hubble Space Telescope} narrow band near-infrared imaging reveals embedded shocks in the dust-buried infrared nucleus of VV 114E. Most of the shocked gas is blueshifted with respect to the quiescent medium, and there is a close spatial correspondence between the shock map and the \emph{Chandra} soft band X-ray image, implying the presence of a galactic superwind. The energy budget of the superwind is in close agreement with the total kinetic power of the cluster winds, confirming the superwind is driven by the starburst.