Implication of a galaxy-scale negative feedback by one of the most powerful multi-phase outflows in a hyper-luminous infrared galaxy at the intermediate redshift

TL;DR

This study investigates a hyper-luminous infrared galaxy at intermediate redshift, revealing powerful multi-phase outflows driven by an active nucleus that likely regulate star formation and galaxy growth through negative feedback mechanisms.

Contribution

It provides detailed observations of the multi-phase outflows in a HyLIRG, demonstrating their potential to influence galaxy evolution via negative feedback.

Findings

Detection of fast ionized outflows extending several kpc.

Identification of massive molecular outflows with high mass-loss rates.

Evidence of outflows inducing shocks and affecting molecular gas excitation.

Abstract

Powerful, galactic outflows driven by Active Galactic Nuclei (AGNs) are commonly considered as a main mechanism to regulate star formation in massive galaxies. Ultra- and hyper-luminous IR galaxies (U/HyLIRGs) are thought to represent a transition phase of galaxies from a rapidly growing period to a quiescent status as gas swept out by outflows, providing a laboratory to investigate outflows and their feedback effects on the hosts. In this paper we report recent Gemini and ALMA observations of a HyLIRG, J1126 at $z=0.46842$, which has been identified with a puzzling co-existence of a fast ionized outflow ($>2000$ km s$^{-1}$) and an intense starburst (star formation rate of 800 $M_{\odot}$ yr$^{-1}$). The Gemini observation shows the fast ionized outflow is extended to several kpc with a mass-loss rate of 180 $M_{\odot}$ yr$^{-1}$. A massive molecular outflow with a high mass-loss rate (2500 $M_{\odot}$ yr$^{-1}$) is revealed by ALMA. The multi-phase outflows show large factors of momentum boost and loading of kinetic power, indicating a driving by thermal pressure of a nuclear hot wind and/or radiation pressure of a highly obscured AGN. In addition to ejection of kinetic energy, it is also found that the powerful outflow can induce an ionizing shock in the galaxy disk and enhance the excitation and dissociation of molecular gas. The powerful outflow probably results in an instantaneous negative feedback and shows potential to regulate the host growth in a long term.