AGN feedback in a galaxy merger: multi-phase, galaxy-scale outflows with a fast molecular gas blob ∼6 kpc away from IRAS F08572+3915^⋆

¹ Astronomy Department, Universidad de Concepción, Av. Esteban Iturra s/n Barrio Universitario, Casilla 160, Concepción, Chile
e-mail: rhc@astro-udec.cl
² Max-Planck-Institute for Extraterrestrial Physics (MPE), Gießenbachstraße 1, 85748 Garching, Germany
³ NOVA Optical Infrared Instrumentation Group at ASTRON, PO Box 2, 7990 AA Dwingeloo, The Netherlands
⁴ Department of Astronomy and Joint Space-Science Institute, Univ. of Maryland, College Park, MD 20742, USA
⁵ Institute of Astronomy and Kavli Institute for Cosmology Cambridge, University of Cambridge, Cambridge, UK
⁶ Space Telescope Science Institute, Baltimore, MD 21218, USA
⁷ Departamento de Física y Matemáticas, Univ. de Alcalá, Campus Universitario, 28871 Alcalá de Henares, Spain
⁸ Department of Physics, Rhodes College, Memphis, TN 38112, USA
⁹ INAF – Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy

Received: 1 August 2019
Accepted: 13 November 2019

Abstract

To understand the role that active galactic nuclei (AGN) feedback plays in galaxy evolution, we need in-depth studies of the multi-phase structure and energetics of galaxy-wide outflows. In this work, we present new, deep (∼50 h) NOEMA CO(1-0) line observations of the molecular gas in the powerful outflow driven by the AGN in the ultra-luminous infrared galaxy IRAS F08572+3915. We spatially resolve the outflow, finding that its most likely configuration is a wide-angle bicone aligned with the kinematic major axis of the rotation disk. The molecular gas in the wind reaches velocities up to approximately ±1200 km s⁻¹ and transports nearly 20% of the molecular gas mass in the system. We detect a second outflow component located ∼6 kpc northwest from the galaxy moving away at ∼900 km s⁻¹, which could be the result of a previous episode of AGN activity. The total mass and energetics of the outflow, which includes contributions from the ionized, neutral, and warm and cold molecular gas phases, is strongly dominated by the cold molecular gas. In fact, the molecular mass outflow rate is higher than the star formation rate, even if we only consider the gas in the outflow that is fast enough to escape the galaxy, which accounts for ∼40% of the total mass of the outflow. This results in an outflow depletion time for the molecular gas in the central ∼1.5 kpc region of only ∼3 Myr, a factor of ∼2 shorter than the depletion time by star formation activity.