Multi-wavelength campaign on NGC 7469

II. Column densities and variability in the X-ray spectrum

¹ Department of Physics, Technion, 32000 Haifa, Israel
e-mail: uperetz@tx.technion.ac.il
² Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
³ SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
⁴ Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
⁵ Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA
⁶ Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
⁷ Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey, RH5 6NT, UK
⁸ INAF-IASF Bologna, via Gobetti 101, 40129 Bologna, Italy
⁹ Nicolaus Copernicus Astronomical Center, Polish Academy of Sciences, Bartycka 18, 00-716 Warsaw, Poland
¹⁰ Department of Astronomy, University of Geneva, 16 Chemin d’Ecogia, 1290 Versoix, Switzerland
¹¹ European Space Astronomy Centre, PO Box 78, 28691 Villanueva de la Cañada, Madrid, Spain
¹² School of Physics and Astronomy, Tel Aviv University, 69978 Tel Aviv, Israel
¹³ Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
¹⁴ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany

Received: 26 July 2017
Accepted: 27 September 2017

Abstract

We have investigated the ionic column density variability of the ionized outflows associated with NGC 7469, to estimate their location and power. This could allow a better understanding of galactic feedback of AGNs to their host galaxies. Analysis of seven XMM-Newton grating observations from 2015 is reported. We used an individual-ion spectral fitting approach, and compared different epochs to accurately determine variability on timescales of years, months, and days. We find no significant column density variability in a ten-year period implying that the outflow is far from the ionizing source. The implied lower bound on the ionization equilibrium time, ten years, constrains the lower limit on the distance to be at least 12 pc, and up to 31 pc, much less but consistent with the 1 kpc wide starburst ring. The ionization distribution of column density is reconstructed from measured column densities, nicely matching results of two 2004 observations, with one large high ionization parameter (ξ) component at 2 < log ξ< 3.5, and one at 0.5 < log ξ< 1 in cgs units. The strong dependence of the expression for kinetic power, ∝ 1 /ξ, hampers tight constraints on the feedback mechanism of outflows with a large range in ionization parameter, which is often observed and indicates a non-conical outflow. The kinetic power of the outflow is estimated here to be within 0.4 and 60% of the Eddington luminosity, depending on the ion used to estimate ξ.