Supermassive Black Hole Winds in X-rays: SUBWAYS

II. HST UV spectroscopy of winds at intermediate redshifts

¹ Space Telescope Science Institute, 3700 San Martin Drive, Baltimore, MD 21218, USA
e-mail: mmehdipour@stsci.edu
² Department of Physics and Astronomy “Augusto Righi” (DIFA), University of Bologna, Via Gobetti, 93/2, 40129 Bologna, Italy
³ INAF-Osservatorio di Astrofisica e Scienza dello Spazio di Bologna, Via Gobetti, 93/3, 40129 Bologna, Italy
⁴ European Space Agency (ESA), European Space Astronomy Centre (ESAC), 28691 Villanueva de la Cañada, Madrid, Spain
⁵ Department of Astrophysical Sciences, Princeton University, 4 Ivy Lane, Princeton, NJ 08544-1001, USA
⁶ Department of Physics, Institute for Astrophysics and Computational Sciences, The Catholic University of America, Washington, DC 20064, USA
⁷ Department of Astronomy, The Ohio State University, 140 West 18th Avenue, Columbus, OH 43210, USA
⁸ Center for Cosmology and Astroparticle Physics, 191 West Woodruff Avenue, Columbus, OH 43210, USA
⁹ Department of Physics, Technion-Israel Institute of Technology, 32000 Haifa, Israel
¹⁰ Dipartimento di Matematica e Fisica, Università degli Studi Roma Tre, via della Vasca Navale 84, 00146 Roma, Italy
¹¹ Department of Physics and Astronomy, College of Charleston, Charleston, SC 29424, USA
¹² SRON Netherlands Institute for Space Research, Niels Bohrweg 4, 2333 CA Leiden, The Netherlands
¹³ Anton Pannekoek Institute, University of Amsterdam, Postbus 94249, 1090 GE Amsterdam, The Netherlands
¹⁴ INAF – Osservatorio Astrofisico di Arcetri, Largo Enrico Fermi 5, 50125 Firenze, Italy
¹⁵ Departament de Física, EEBE, Universitat Politècnica de Catalunya, Av. Eduard Maristany 16, 08019 Barcelona, Spain
¹⁶ INAF – Istituto di Astrofisica e Planetologia Spaziali (IAPS), via Fosso del Cavaliere, Roma 00133, Italy
¹⁷ Department of Physics and Astronomy, Georgia State University, Atlanta, GA 30303, USA
¹⁸ Université Grenoble Alpes, CNRS, IPAG, 38000 Grenoble, France
¹⁹ Centro de Astrobiologia (CAB), CSIC-INTA, Camino Bajo del Castillo s/n, 28692 Villanueva de la Cañada, Madrid, Spain
²⁰ Leiden Observatory, Leiden University, PO Box 9513 2300 RA Leiden, The Netherlands
²¹ School of Physics and Astronomy, University of Leicester, Leicester LE1 7RH, UK
²² Instituto de Astronomía, Universidad Nacional Autónoma de México, Circuito Exterior, Ciudad Universitaria, Ciudad de México 04510, Mexico
²³ INAF – Osservatorio Astronomico di Roma, Via Frascati 33, 00040 Monte Porzio Catone, Italy
²⁴ Space Science Data Center, Agenzia Spaziale Italiana, Via del Politecnico snc, 00133 Roma, Italy
²⁵ Centro de Astrobiología, (CAB, CSIC–INTA), Departamento de Astrofísica, Cra. de Ajalvir Km. 4, 28850 Torrejón de Ardoz, Madrid, Spain
²⁶ INAF-Osservatorio Astronomico di Brera, Via E. Bianchi 46, 23807 Merate (LC), Italy
²⁷ Max-Planck-Institut für Extraterrestrische Physik, Giessenbachstrasse, 85748 Garching, Germany
²⁸ Physics Department, Tor Vergata University of Rome, Via della Ricerca Scientifica 1, 00133 Rome, Italy
²⁹ Department of Astronomy, University of Maryland, College Park, MD 20742, USA
³⁰ NASA – Goddard Space Flight Center, Code 662, Greenbelt, MD 20771, USA
³¹ INFN – Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Rome, Italy

Received: 23 September 2022
Accepted: 2 November 2022

Abstract

We present a UV spectroscopic study of ionized outflows in 21 active galactic nuclei (AGN), observed with the Hubble Space Telescope (HST). The targets of the Supermassive Black Hole Winds in X-rays (SUBWAYS) sample were selected with the aim to probe the parameter space of the underexplored AGN between the local Seyfert galaxies and the luminous quasars at high redshifts. Our targets, spanning redshifts of 0.1–0.4 and bolometric luminosities (L_bol) of 10⁴⁵–10⁴⁶ erg s⁻¹, have been observed with a large multi-wavelength campaign using XMM-Newton, NuSTAR, and HST. Here, we model the UV spectra and look for different types of AGN outflows that may produce either narrow or broad UV absorption features. We examine the relations between the observed UV outflows and other properties of the AGN. We find that 60% of our targets show a presence of outflowing H I absorption, while 40% exhibit ionized outflows seen as absorption by either C IV, N V, or O VI. This is comparable to the occurrence of ionized outflows seen in the local Seyfert galaxies. All UV absorption lines in the sample are relatively narrow, with outflow velocities reaching up to −3300 km s⁻¹. We did not detect any UV counterparts to the X-ray ultra-fast outflows (UFOs), most likely due to their being too highly ionized to produce significant UV absorption. However, all SUBWAYS targets with an X-ray UFO that have HST data demonstrate the presence of UV outflows at lower velocities. We find significant correlations between the column density (N) of the UV ions and L_bol of the AGN, with N_H I decreasing with L_bol, while N_O VI is increasing with L_bol. This is likely to be a photoionization effect, where toward higher AGN luminosities, the wind becomes more ionized, resulting in less absorption by neutral or low-ionization ions and more absorption by high-ionization ions. In addition, we find that N of the UV ions decreases as their outflow velocity increases. This may be explained by a mechanical power that is evacuating the UV-absorbing medium. Our observed relations are consistent with multiphase AGN feeding and feedback simulations indicating that a combination of both radiative and mechanical processes are in play.