Searching for Evidence of Energetic Feedback in Distant Galaxies: A Galaxy Wide Outflow in a z~2 Ultraluminous Infrared Galaxy

TL;DR

This study presents evidence of a large-scale energetic outflow in a z~2 ultraluminous infrared galaxy, supporting models that require such outflows to regulate galaxy and black hole growth at high redshift.

Contribution

It provides the first detailed observation of a galaxy-wide outflow in a typical high-redshift ULIRG, expanding understanding beyond rare radio galaxies.

Findings

Large-scale outflow extends 4-8 kpc with high velocity and broad [OIII] emission.

Outflow energy (~10^59 ergs) can be driven by AGN winds or supernovae, not radio jets.

Outflow energy is comparable to galaxy spheroid binding energy, impacting galaxy evolution.

Abstract

Leading models of galaxy formation require large-scale energetic outflows to regulate the growth of distant galaxies and their central black holes. However, current observational support for this hypothesis at high redshift is mostly limited to rare z>2 radio galaxies. Here we present Gemini-North NIFS Intregral Field Unit (IFU) observations of the [OIII] emission from a z~2 ultraluminous infrared galaxy (L_IR>10^12 solar luminosities) with an optically identified Active Galactic Nucleus (AGN). The spatial extent (~4-8 kpc) of the high velocity and broad [OIII] emission are consistent with that found in z>2 radio galaxies, indicating the presence of a large-scale energetic outflow in a galaxy population potentially orders of magnitude more common than distant radio galaxies. The low radio luminosity of this system indicates that radio-bright jets are unlikely to be responsible for driving the outflow. However, the estimated energy input required to produce the large-scale outflow signatures (of order ~10^59 ergs over ~30 Myrs) could be delivered by a wind radiatively driven by the AGN and/or supernovae winds from intense star formation. The energy injection required to drive the outflow is comparable to the estimated binding energy of the galaxy spheroid, suggesting that it can have a significant impact on the evolution of the galaxy. We argue that the outflow observed in this system is likely to be comparatively typical of the high-redshift ULIRG population and discuss the implications of these observations for galaxy formation models.