Multi-wavelength campaign on NGC 7469

V. Analysis of the HST/COS observations: Super solar metallicity, distance, and trough variation models

¹ Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA
e-mail: arav@vt.edu
² Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
³ Department of Physics, Technion-Israel Institute of Technology, 32000 Haifa, Israel
⁴ SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 Utrecht, The Netherlands
⁵ Leiden Observatory, Leiden University, Post Office Box 9513, 2300 Leiden, The Netherlands
⁶ Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
⁷ Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
⁸ INAF-IASF Bologna, Via Gobetti 101, 40129 Bologna, Italy
⁹ N. Copernicus Astronomical Center of the Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw, Poland
¹⁰ Italian Space Agency (ASI), Via del Politecnico snc, Rome, Italy
¹¹ European Space Astronomy Centre, PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
¹² School of Physics and Astronomy and Wise Observatory, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel Aviv University, Tel Aviv 6997801, Israel
¹³ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
¹⁴ INAF, Osservatorio Astronomico di Brera Merate, Via E. Bianchi 46, 23807 Merate, Italy
¹⁵ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany

Received: 22 February 2019
Accepted: 19 July 2019

Abstract

Context. AGN outflows are thought to influence the evolution of their host galaxies and their super massive black holes. To better understand these outflows, we executed a deep multiwavelength campaign on NGC 7469. The resulting data, combined with those of earlier epochs, allowed us to construct a comprehensive physical, spatial, and temporal picture for this AGN wind.

Aims. Our aim is to determine the distance of the UV outflow components from the central source, their abundances and total column-density, and the mechanism responsible for their observed absorption variability.

Methods. We studied the UV spectra acquired during the campaign as well as from three previous epochs (2002–2010). Our main analysis tools are ionic column-density extraction techniques and photoionization models (both equilibrium and time-dependent models) based on the code CLOUDY.

Results. For component 1 (at –600 km s⁻¹) our findings include the following: metallicity that is roughly twice solar; a simple model based on a fixed total column-density absorber, reacting to changes in ionizing illumination that matches the different ionic column densities derived from four spectroscopic epochs spanning 13 years; and a distance of R = 6^+2.5_−1.5 pc from the central source. Component 2 (at –1430 km s⁻¹) has shallow troughs and is at a much larger R. For component 3 (at –1880 km s⁻¹) our findings include: a similar metallicity to component 1; a photoionization-based model can explain the major features of its complicated absorption trough variability and an upper limit of 60 or 150 pc on R. This upper limit is consistent and complementary to the X-ray derived lower limit of 12 or 31 pc for R. The total column density of the UV phase is roughly 1% and 0.1% of the lower and upper ionization components of the warm absorber, respectively.

Conclusions. The NGC 7469 outflow shows super-solar metallicity similar to the outflow in Mrk 279, carbon and nitrogen are twice and four times more abundant than their solar values, respectively. Similar to the NGC 5548 case, a simple model can explain the physical characteristics and the variability observed in the outflow.