Disc wind or disc line? The extraordinary Fe-K feature of Mrk 1513

¹ INAF Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone, RM, Italy
e-mail: riccardo.middei@ssdc.asi.it
² Space Science Data Center, Agenzia Spaziale Italiana, Via del Politecnico snc, 00133 Roma, Italy
³ INAF – Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
⁴ Quasar Science Resources SL for ESA, European Space Astronomy Centre (ESAC), Science Operations Department, 28692 Villanueva de la Cañada, Madrid, Spain
⁵ Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, Via della Vasca Navale 84, 00146 Roma, Italy
⁶ Department of Physics, Institute for Astrophysics and Computational Sciences, The Catholic University of America, Washington, DC 20064, USA
⁷ INAF, Osservatorio Astronomico di Brera, Via Bianchi 46, 23807 Merate, LC, Italy
⁸ Dipartimento di Fisica, Università di Trento, Via Sommarive 14, 38123 Trento, Italy

Received: 14 September 2023
Accepted: 28 September 2023

Abstract

We discuss the origin of a very unusual spectral structure observed in the Fe-K band of the Seyfert galaxy Mrk 1513, a local (z = 0.063) active galactic nucleus (AGN) that is efficiently accreting matter onto its central supermassive black hole (L_bol/L_Edd ∼ 0.5). We consider the highest quality X-ray observation of this source available to date, performed in 2003 by XMM–Newton. The hard X-ray spectrum is characterised by a remarkable spectral drop at ∼7 keV, which can be interpreted as either the onset of a broad absorption trough or the blue wing of a relativistic emission line. Overall, this complex feature is significant at > 5σ, and it is qualitatively reminiscent of a P Cygni profile. A serendipitous spectrum of lower quality taken by XMM–Newton in 2015 qualitatively confirms the presence of similar Fe-K structures. Although it is not possible to distinguish between the two physical scenarios on sheer statistical grounds with the current data, several considerations lend weight to the possibility that Mrk 1513 is actually hosting a persistent outflow at accretion-disc scales, thus adding to the select number of known AGN in which a wide-angle X-ray wind has been identified so far.