ALBERT

Description: Ongoing studies with XMM–Newton have shown that powerful accretion disc winds, as revealed through highly ionized Fe K-shell absorption at E  ≥ 6.7 keV, are present in a significant fraction of active galactic nuclei (AGNs) in the local Universe (Tombesi et al. 2010a ). In Gofford et al., we analysed a sample of 51 Suzaku -observed AGNs and independently detected Fe K absorption in ~40 per cent of the sample, and we measured the properties of the absorbing gas. In this work, we build upon these results to consider the properties of the associated wind. On average, the fast winds ( v w  〉 0.01 c ) are located 〈 r 〉 ~ 10 15–18  cm (typically ~10 2–4 r s ) from their black hole, their mass outflow rates are of the order of $\langle \skew{3}\dot{M}_{\rm w}\rangle \sim 0.01\hbox{--}1$  M  yr –1 or ${\sim }(0.01\hbox{--}1)\skew{3}\dot{M}_{\rm Edd}$ and kinetic power is constrained to 〈 L w 〉 ~ 10 43–45  erg s –1 , equivalent to ~(0.1–10 per cent) L Edd . We find a fundamental correlation between the source bolometric luminosity and the wind velocity, with $v_{\rm w} \propto L_{\rm bol}^{\alpha }$ and $\alpha =0.4^{+0.3}_{-0.2}$ (90 per cent confidence), which indicates that more luminous AGN tend to harbour faster Fe K winds. The mass outflow rate $\skew{3}\dot{M}_{\rm w}$ , kinetic power L w and momentum flux $\dot{p}_{\rm w}$ of the winds are also consequently correlated with L bol , such that more massive and more energetic winds are present in more luminous AGN. We investigate these properties in the framework of a continuum-driven wind, showing that the observed relationships are broadly consistent with a wind being accelerated by continuum-scattering. We find that, globally, a significant fraction (~85 per cent) of the sample can plausibly exceed the L w / L bol  ~ 0.5 per cent threshold thought necessary for feedback, while 45 per cent may also exceed the less conservative ~5 per cent of L bol threshold as well. This suggests that the winds may be energetically significant for AGN–host-galaxy feedback processes.

Description: The study of winds in active galactic nuclei (AGNs) is of utmost importance as they may provide the long sought-after link between the central black hole and the host galaxy, establishing the AGN feedback. Recently, Laha et al. reported the X-ray analysis of a sample of 26 Seyferts observed with XMM–Newton , which are part of the so-called warm absorbers in X-rays (WAX) sample. They claim the non-detection of Fe K absorbers indicative of ultrafast outflows in four observations previously analysed by Tombesi et al. They mainly impute the Tombesi et al. detections to an improper modelling of the underlying continuum in the E = 4–10 keV band. We therefore re-address here the robustness of these detections and we find that the main reason for the claimed non-detections is likely due to their use of single events only spectra, which reduces the total counts by 40 per cent. Performing a re-analysis of the data in the whole E = 0.3–10 keV energy band using their models and spectra including also double events, we find that the blueshifted Fe K absorption lines are indeed detected at 〉99 per cent. This work demonstrates the robustness of these detections in XMM–Newton even including complex model components such as reflection, relativistic lines and warm absorbers.

Description: We present a detailed analysis of a recent, 2013 Suzaku campaign on the nearby ( z  = 0.184) luminous ( L bol  ~ 10 47 erg s –1 ) quasar PDS 456. This consisted of three observations, covering a total duration of ~1 Ms and a net exposure of 455 ks. During these observations, the X-ray flux was unusually low, suppressed by a factor of 〉10 in the soft X-ray band when compared to previous observations. We investigated the broad-band continuum by constructing a spectral energy distribution (SED), making use of the optical/UV photometry and hard X-ray spectra from the later simultaneous XMM–Newton and NuSTAR campaign in 2014. The high-energy part of this low-flux SED cannot be accounted for by physically self-consistent accretion disc and corona models without attenuation by absorbing gas, which partially covers a substantial fraction of the line of sight towards the X-ray continuum. At least two layers of absorbing gas are required, of column density log ( N H,low /cm –2 ) = 22.3 ± 0.1 and log ( N H,high /cm –2 ) = 23.2 ± 0.1, with average line-of-sight covering factors of ~80 per cent (with typical ~5 per cent variations) and 60 per cent (±10–15 per cent), respectively. During these observations PDS 456 displays significant short-term X-ray spectral variability, on time-scales of ~100 ks, which can be accounted for by variable covering of the absorbing gas along the line of sight. The partial covering absorber prefers an outflow velocity of $v_{\rm pc} = 0.25^{+0.01}_{-0.05}\,c$ at the 〉99.9 per cent confidence level over the case where v pc  = 0. This is consistent with the velocity of the highly ionized outflow responsible for the blueshifted iron K absorption profile. We therefore suggest that the partial covering clouds could be the denser, or clumpy part of an inhomogeneous accretion disc wind. Finally estimates are placed upon the size-scale of the X-ray emission region from the source variability. The radial extent of the X-ray emitter is found to be of the order ~15–20 R g , although the hard X-ray (〉2 keV) emission may originate from a more compact or patchy corona of hot electrons, which is typically ~6–8 R g in size.

Description: Recent X-ray observations show absorbing winds with velocities up to mildly relativistic values of the order of ~0.1 c in a limited sample of six broad-line radio galaxies. They are observed as blueshifted Fe  xxv–xxvi K-shell absorption lines, similarly to the ultrafast outflows (UFOs) reported in Seyferts and quasars. In this work we extend the search for such Fe K absorption lines to a larger sample of 26 radio-loud active galactic nuclei (AGN) observed with XMM–Newton and Suzaku . The sample is drawn from the Swift Burst Alert Telescope 58-month catalogue and blazars are excluded. X-ray bright Fanaroff–Riley Class II radio galaxies constitute the majority of the sources. Combining the results of this analysis with those in the literature we find that UFOs are detected in 〉27 per cent of the sources. However, correcting for the number of spectra with insufficient signal-to-noise ratio, we can estimate that the incidence of UFOs is this sample of radio-loud AGN is likely in the range f ~= (50 ± 20) per cent. A photoionization modelling of the absorption lines with xstar allows us to estimate the distribution of their main parameters. The observed outflow velocities are broadly distributed between v out 1000 km s –1 and v out ~= 0.4 c , with mean and median values of v out ~= 0.133 c and v out ~= 0.117 c , respectively. The material is highly ionized, with an average ionization parameter of log ~= 4.5 erg s –1  cm, and the column densities are larger than N H  〉 10 22  cm –2 . Overall, these characteristics are consistent with the presence of complex accretion disc winds in a significant fraction of radio-loud AGN and demonstrate that the presence of relativistic jets does not preclude the existence of winds, in accordance with several theoretical models.

Description: We present a combined Suzaku and Swift BAT broad-band E  = 0.6–200 keV spectral analysis of three 3C 111 observations obtained in 2010. The data are well described with an absorbed power-law continuum and a weak ( R  ~= 0.2) cold reflection component from distant material. We constrain the continuum cutoff at E C  ~= 150–200 keV, which is in accordance with X-ray Comptonization corona models and supports claims that the jet emission is only dominant at much higher energies. Fe xxvi Lyα emission and absorption lines are also present in the first and second observations, respectively. The modelling and interpretation of the emission line is complex and we explore three possibilities. If originating from ionized-disc reflection, this should be emitted at r in  ≥ 50 r g or, in the lamp-post configuration, the illuminating source should be at a height of h  ≥ 30 r g above the black hole. Alternatively, the line could be modelled with a hot collisionally ionized plasma with temperature $kT = 22.0^{+6.1}_{-3.2}$ keV or a photoionized plasma with $\log \xi = 4.52^{+0.10}_{-0.16}$ erg s –1 cm and column density N H  〉 3 10 23 cm –2 . However, the first and second scenarios are less favoured on statistical and physical grounds, respectively. The blueshifted absorption line in the second observation can be modelled as an ultrafast outflow (UFO) with ionization parameter $\log \xi = 4.47^{+0.76}_{-0.04}$ erg s –1 cm, column density $N_\mathrm{H} = (5.3^{+1.8}_{-1.3})\times 10^{22}$ cm –2 and outflow velocity v out  = 0.104 ± 0.006 c . Interestingly, the parameters of the photoionized emission model remarkably match those of the absorbing UFO, supporting the possibility that the same material could be responsible for both emission and absorption. We suggest an outburst scenario in which an accretion disc wind, initially lying out of the line of sight and observed in emission, then crosses our view to the source and it is observed in absorption as a mildly relativistic UFO.

Description: The existence of ionized X-ray absorbing layers of gas along the line of sight to the nuclei of Seyfert galaxies is a well established observational fact. This material is systematically outflowing and shows a large range in parameters. However, its actual nature and dynamics are still not clear. In order to gain insights into these important issues we performed a literature search for papers reporting the parameters of the soft X-ray warm absorbers (WAs) in 35 type 1 Seyferts and compared their properties to those of the ultra-fast outflows (UFOs) detected in the same sample. The fraction of sources with WAs is 〉60 per cent, consistent with previous studies. The fraction of sources with UFOs is 〉34 per cent, 〉67 per cent of which also show WAs. The large dynamic range obtained when considering all the absorbers together, spanning several orders of magnitude in ionization, column, velocity and distance allows us, for the first time, to investigate general relations among them. In particular, we find significant correlations indicating that the closer the absorber is to the central black hole, the higher the ionization, column, outflow velocity and consequently the mechanical power. In all the cases, the absorbers continuously populate the whole parameter space, with the WAs and the UFOs lying always at the two ends of the distribution. These evidence strongly suggest that these absorbers, often considered of different types, could actually represent parts of a single large-scale stratified outflow observed at different locations from the black hole. The UFOs are likely launched from the inner accretion disc and the WAs at larger distances, such as the outer disc and/or torus. We argue that the observed parameters and correlations are, to date, consistent with both radiation pressure through Compton scattering and magnetohydrodynamic processes contributing to the outflow acceleration, the latter playing a major role. Most of the absorbers, especially the UFOs, show a sufficiently high mechanical power (at least ~0.5 per cent of the bolometric luminosity) to provide a significant contribution to active galactic nuclei (AGN) feedback and thus to the evolution of the host galaxy. In this regard, we find possible evidence for the interaction of the AGN wind with the surrounding environment on large scales.

Description: We present the results of a new spectroscopic study of Fe K-band absorption in active galactic nuclei (AGN). Using data obtained from the Suzaku public archive we have performed a statistically driven blind search for Fe  xxv Heα and/or Fe  xxvi Lyα absorption lines in a large sample of 51 Type 1.0-1.9 AGN. Through extensive Monte Carlo simulations we find that statistically significant absorption is detected at E 6.7 keV in 20/51 sources at the P MC ≥ 95 per cent level, which corresponds to ~40 per cent of the total sample. In all cases, individual absorption lines are detected independently and simultaneously amongst the two (or three) available X-ray imaging spectrometer detectors, which confirms the robustness of the line detections. The most frequently observed outflow phenomenology consists of two discrete absorption troughs corresponding to Fe  xxv Heα and Fe  xxvi Lyα at a common velocity shift. From xstar fitting the mean column density and ionization parameter for the Fe K absorption components are log ( N H /cm –2 ) 23 and log (/erg cm s –1 ) 4.5, respectively. Measured outflow velocities span a continuous range from 〈1500 km s –1 up to ~100 000 km s –1 , with mean and median values of ~0.1 c and ~0.056 c, respectively. The results of this work are consistent with those recently obtained using XMM–Newton and independently provides strong evidence for the existence of very highly ionized circumnuclear material in a significant fraction of both radio-quiet and radio-loud AGN in the local universe.