Another X-ray UFO without a momentum-boosted molecular outflow

ALMA CO(1–0) observations of the galaxy pair IRAS 05054+1718

¹ Department of Astrophysics, University of Vienna, Türkenschanzstrasse 17, 1180 Vienna, Austria
e-mail: francesca.bonanomi@univie.ac.at
² INAF – Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy
³ Department of Physics G. Occhialini, University of Milano-Bicocca, Piazza della Scienza 3, 20126 Milan, Italy
⁴ Institute of Theoretical Astrophysics, University of Oslo, PO Box 1029, Blindern, 0315 Oslo, Norway
⁵ INAF – Osservatorio Astronomico di Brera, Via Bianchi 46, 23807 Merate, (LC), Italy
⁶ Department of Physics, Institute for Astrophysics and Computational Sciences, The Catholic University of America, Washington, DC 20064, USA
⁷ Dipartimento di Fisica e Astronomia “Augusto Righi”, Alma Mater Studiorum, Università degli Studi di Bologna, Via Gobetti 93/2, 40129 Bologna, Italy
⁸ INAF – Osservatorio di Astrofisica e Scienza delle Spazio di Bologna, OAS, Via Gobetti 93/3, 40129 Bologna, Italy
⁹ Department of Astronomy, Oskar Klein Centre, Stockholm University, AlbaNova University Centre, 106 91 Stockholm, Sweden
¹⁰ European Space Astronomy Centre (ESA/ESAC), 28691 Villanueva de la Canada, Madrid, Spain

Received: 7 December 2022
Accepted: 28 February 2023

Abstract

We present Atacama Large Millimetre/submillimetre Array (ALMA) CO(1–0) observations of the nearby infrared luminous (LIRG) galaxy pair IRAS 05054+1718 (also known as CGCG 468-002), as well as a new analysis of X-ray data of this source collected between 2012 and 2021 using the Nuclear Spectroscopic Telescope Array (NuSTAR), Swift, and the XMM-Newton satellites. The western component of the pair, NED01, hosts a Seyfert 1.9 nucleus that is responsible for launching a powerful X-ray ultra-fast outflow (UFO). Our X-ray spectral analysis suggests that the UFO could be variable or multi-component in velocity, ranging from v/c ∼ −0.12 (as seen in Swift) to v/c ∼ −0.23 (as seen in NuSTAR), and constrains its momentum flux to be ṗ_out^X−ray ∼ (4 ± 2) × 10³⁴ g cm s⁻². The ALMA CO(1–0) observations, obtained with an angular resolution of 2.2″, although targeting mainly NED01, also include the eastern component of the pair, NED02, a less-studied LIRG with no clear evidence of an active galactic nucleus (AGN). We study the CO(1–0) kinematics in the two galaxies using the 3D-BAROLO code. In both sources we can model the bulk of the CO(1–0) emission with rotating disks and, after subtracting the best-fit models, we detect compact residual emission at S/N = 15 within ∼3 kpc of the centre. A molecular outflow in NED01, if present, cannot be brighter than such residuals, implying an upper limit on its outflow rate of Ṁ_out^mol ≲ 19 ± 14 M_⊙ yr⁻¹ and on its momentum rate of ṗ_out^mol ≲ (2.7 ± 2.4) × 10³⁴ g cm s⁻¹. Combined with the revised energetics of the X-ray wind, we derive an upper limit on the momentum rate ratio of ṗ_out^mol/ṗ_out^X−ray < 0.67. We discuss these results in the context of the expectations of AGN feedback models, and we propose that the X-ray disk wind in NED01 has not significantly impacted the molecular gas reservoir (yet), and we can constrain its effect to be much smaller than expectations of AGN ‘energy-driven’ feedback models. We also consider and discuss the hypothesis of asymmetries of the molecular disk not properly captured by the 3D-BAROLO code. Our results highlight the challenges in testing the predictions of popular AGN disk-wind feedback theories, even in the presence of good-quality multi-wavelength observations.