A broadband X-ray view of the NLSy1 1E 0754.6+3928

¹ Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Rome, Italy
e-mail: riccardo.middei@uniroma3.it
² Dipartimento di Fisica, Università di Roma “Tor Vergata”, via della Ricerca Scientifica 1, 00133 Rome, Italy
³ INAF Astronomical Observatory of Rome, Via Frascati 33, 00078 Monteporzio Catone, Italy
⁴ Department of Astronomy, University of Maryland, College Park, MD 20742, USA
⁵ NASA/Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA
⁶ INAF – Osservatorio Astronomico di Brera, Via Brera 28, 20121 Milano, Italy
⁷ Centro de Astrobiología (CSIC-INTA), Dep. de Astrofísica; LAEFF, Villanueva de la Cañada, Madrid, Spain
⁸ ASI – Unità di Ricerca Scientifica, Via del Politecnico snc, 00133 Rome, Italy
⁹ European Space Agency (ESA), European Space Astronomy Centre (ESAC), 28691 Villanueva de la Cañada, Madrid, Spain
¹⁰ Univ. Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
¹¹ INAF/IASF Bologna, via Gobetti 101, 40129 Bologna, Italy

Received: 14 September 2019
Accepted: 9 January 2020

Abstract

Context. The soft X-ray band of many active galactic nuclei (AGNs) is affected by obscuration due to partially ionised matter crossing our line of sight. In this context, two past XMM-Newton observations that were six months apart and a simultaneous NuSTAR-Swift exposure of the Narrow Line Seyfert 1 galaxy 1E 0754.6+3928, which was approximately eight years later, revealed an intense and variable warm absorber (WA) and hints of additional absorbers in the Fe Kα band.

Aims. We aim to provide the first X-ray characterisation of this AGN by discussing its broadband (0.3–79 keV) spectrum and temporal properties.

Methods. We conduct a temporal and spectroscopic analysis on two ∼10 ks (net exposure) XMM-Newton snapshots performed in April and October 2006. We also study the high energy behaviour of 1E 0754.6+3928 and model its broadband spectrum by using simultaneous Swift-NuSTAR data. Both phenomenological and physically motivated models are tested.

Results. We find the presence of flux variability of ∼150% and 30% for 0.3–2 and 2–10 keV bands, respectively, and spectral changes at months timescales of ΔΓ ∼ 0.4. A reflection component that is consistent with being constant over years and arising from relatively cold material that is far from the central super massive black hole is detected. The main spectral feature shaping the 1E 0754.6+3928 spectrum is a WA. Such a component is persistent over the years and the variability of its ionisation and column density is observed down on months in the ranges 3 × 10²²cm⁻² ≲  N_H ≲ 7.2 × 10²²cm⁻² and 1.5 ≲ log (ξ/erg s⁻¹ cm) ≲ 2.1. Despite the short exposures, we find possible evidence of two additional high-ionisation and high-velocity outflow components in absorption.

Conclusions. Our analysis suggests the existence of a complex system of absorbers in 1E 0754.6+3928. Longer exposures are required in order to characterise, on more solid grounds, the absorbers in this AGN.