||Revealing an Energetic Galaxy-Wide Outflow in a z ≈ 2 Ultraluminous Infrared Galaxy
||427, Accretion and Ejection in AGN: a Global View
||Alexander, D. M.; Swinbank, A. M.; Smail, I.; McDermid, R.; Nesvadba, N. P. H.
||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 [O iii]λ5007 emission from
a z ≈ 2 ultraluminous infrared galaxy (ULIRG; LIR > 1012 L☉) with an optically
identified Active Galactic Nucleus (AGN). The spatial extent (≈ 4–8 kpc) of the
high velocity and broad [O iii] 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 ≈ 1059 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.