Multi-wavelength campaign on NCG 7469

IV. The broad-band X-ray spectrum

¹ Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
e-mail: riccardo.middei@uniroma3.it
² INAF - IASF Bologna, via Gobetti 101, 40129 Bologna, Italy
³ Univ. Grenoble-Alpes, CNRS, IPAG, 38000 Grenoble, France
⁴ Department of Physics, Technion, Haifa 32000, Israel
⁵ Department of Physics, Virginia Tech, Blacksburg, VA 24061, USA
⁶ Department of Astronomy, University of Maryland, College Park, USA
⁷ Mullard Space Science Laboratory, University College London, Holmbury St. Mary, Dorking, Surrey RH5 6NT, UK
⁸ SRON Netherlands Institute for Space Research, Sorbonnelaan 2, 3584 CA Utrecht, The Netherlands
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, Villanueva de la Cañada, PO Box 78, 28691 Madrid, Spain
¹² Leiden Observatory, Leiden University, PO Box 9513, 2300 RA Leiden, The Netherlands
¹³ School of Physics & Astronomy and Wise Observatory, Raymond and Beverly Sackler Faculty of Exact Sciences, Tel-Aviv University, Tel-Aviv 69978, Israel
¹⁴ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
¹⁵ Max-Planck-Institut für extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany

Received: 29 January 2018
Accepted: 19 March 2018

Abstract

We conducted a multi-wavelength 6-month campaign to observe the Seyfert Galaxy NGC 7469, using the space-based observatories HST, Swift, XMM-Newton and NuSTAR. We report the results of the spectral analysis of the seven simultaneous XMM-Newton and NuSTAR observations. The source shows significant flux variability within each observation, but the average flux is less variable among the different pointings of our campaign. Our spectral analysis reveals a prominent narrow neutral Fe Kα emission line in all the spectra and weaker contributions from Fe Kβ, neutral Ni Kα, and ionized iron. We find no evidence for variability or relativistic effects acting on the emission lines, which indicates that they originate from distant material. In the joint analysis of XMM-Newton and NuSTAR data, a constant photon index is found (Γ = 1.78 ± 0.02) together with a high energy cut-off E_cut = 170₋₄₀⁺⁶⁰ keV. Adopting a self-consistent Comptonization model, these values correspond to an average coronal electron temperature of kT = 45₋₁₂⁺¹⁵ keV and, assuming a spherical geometry, an optical depth τ = 2.6 ± 0.9. The reflection component is consistent with being constant and the reflection fraction is in the range R = 0.3−0.6. A prominent soft excess dominates the spectra below 4 keV. This is best fit with a second Comptonization component, arising from a warm corona with an average kT = 0.67 ± 0.03 keV and a corresponding optical depth τ = 9.2 ± 0.2.