Searching for molecular outflows in Hyper-Luminous Infrared Galaxies

TL;DR

This study investigates molecular outflows in five Hyper-Luminous Infrared Galaxies using Herschel data, detecting outflows in three and suggesting AGN activity as the primary driver.

Contribution

First to analyze molecular outflows in Hyper-Luminous Infrared Galaxies using Herschel OH observations, highlighting outflow velocities independent of star formation rates.

Findings

Detected OH doublet in 3 out of 5 galaxies.

Identified molecular outflows with velocities up to ~1500 km/s.

Outflows likely driven by embedded AGN rather than star formation.

Abstract

We present constraints on the molecular outflows in a sample of five Hyper-Luminous Infrared Galaxies using Herschel observations of the OH doublet at 119 {\mu}m. We have detected the OH doublet in three cases: one purely in emission and two purely in absorption. The observed emission profile has a significant blueshifted wing suggesting the possibility of tracing an outflow. Out of the two absorption profiles, one seems to be consistent with the systemic velocity while the other clearly indicates the presence of a molecular outflow whose maximum velocity is about ~1500 km/s. Our analysis shows that this system is in general agreement with previous results on Ultra-luminous Infrared Galaxies and QSOs, whose outflow velocities do not seem to correlate with stellar masses or starburst luminosities (star formation rates). Instead the galaxy outflow likely arises from an embedded AGN.