68 research outputs found
Supermassive black hole winds in X-rays: SUBWAYS: II. HST UV spectroscopy of winds at intermediate redshifts
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 (Lbol) 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 Lbol of the AGN, with NH I decreasing with Lbol, while NO VI is increasing with Lbol. 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.Peer ReviewedPostprint (published version
Supermassive black hole winds in X-rays: SUBWAYS: I. Ultra-fast outflows in quasars beyond the local Universe
We present a new X-ray spectroscopic study of 22 luminous (2 × 1045 ¿ Lbol/erg s-1 ¿ 2 × 1046) active galactic nuclei (AGNs) at intermediate redshifts (0.1 ¿ z ¿ 0.4), as part of the SUpermassive Black hole Winds in the x-rAYS (SUBWAYS) sample, mostly composed of quasars and type 1 AGNs. Here, 17 targets were observed with XMM-Newton in 2019–2020, and the remaining 5 are from previous observations. The aim of this large campaign (1.45 Ms duration) is to characterise the various manifestations of winds in the X-rays driven from supermassive black holes in AGNs. In this paper we focus on the search for and characterisation of ultra-fast outflows (UFOs), which are typically detected through blueshifted absorption troughs in the Fe K band (E > 7 keV). By following Monte Carlo procedures, we confirm the detection of absorption lines corresponding to highly ionised iron (e.g. Fe¿XXV Ha and Fe¿XXVI Lya) in 7 out of 22 sources at the ¿95% confidence level (for each individual line). The global combined probability of such absorption features in the sample is > 99.9%. The SUBWAYS campaign, based on XMM-Newton, extends to higher luminosities and redshifts than previous local studies on Seyferts. We find a UFO detection fraction of ~30% of the total sample, which is in agreement with previous findings. This work independently provides further support for the existence of highly ionised matter propagating at mildly relativistic speeds (¿0.1c) in a considerable fraction of AGNs over a broad range of luminosities, which is believed to play a key role in the self-regulated AGN feeding-feedback cycle, as also supported by hydrodynamical multi-phase simulations.Peer ReviewedPostprint (published version
Active Galaxies in the UV
In this article we present different aspects of AGN studies demonstrating the
importance of the UV spectral range. Most important diagnostic lines for
studying the general physical conditions as well as the metalicities in the
central broad line region in AGN are emitted in the UV. The UV/FUV continuum in
AGN excites not only the emission lines in the immediate surrounding but it is
responsible for the ionization of the intergalactic medium in the early stages
of the universe. Variability studies of the emission line profiles of AGN in
the UV give us information on the structure and kinematics of the immediate
surrounding of the central supermassive black hole as well as on its mass
itself.Comment: 29 pages, 13 figures, Ap&SS in pres
X-ray/UV campaign on the Mrk 279 outflow: density diagnostics in Active Galactic Nuclei using O V K-shell absorption lines
One of the main problems in modeling the ionised outflows in Active Galactic
Nuclei is the unknown distance of the outflowing wind to the central source.
Only if the density is known this distance can be determined through the
ionisation parameter. Here we study density diagnostics based upon O V
transitions. O V is known to have metastable levels that are density dependent.
We study the population of those levels under photoionisation equilibrium
conditions and determine for which parameter range they can have a significant
population. We find that resonance line trapping plays an important role in
reducing the critical densities above which the metastable population becomes
important. We investigate the K-shell absorption lines from these metastable
levels. Provided that there is a sufficient population of the metastable
levels, the corresponding K-shell absorption lines are detectable and are well
separated from the main absorption line originating from the ground state. We
then present the Chandra LETGS spectrum of the Seyfert 1 galaxy Mrk 279 that
may show for the first time the presence of these metastable level absorption
lines. A firm identification is not yet possible due to both uncertainties in
the observed wavelength of the strongest line as well as uncertainties in the
predicted wavelength. If the line is indeed due to absorption from O V, then we
deduce a distance to the central source of one light week to a few light
months, depending upon the importance of additional heating processes.Comment: 10 pages, 8 figures, submitted to Astronomy & Astrophysics, main
journa
10 Yr transformation of the obscuring wind in NGC 5548
GalaxiesHigh Energy Astrophysic
Multiwavelength observations of the obscuring wind in the radio-quiet quasar MR 2251-178
High Energy Astrophysic
- …