Context. It is generally believed that the supermassive black holes in active galactic nuclei (AGN) and stellar-mass black holes in X-ray binaries (XRBs) work in a similar way. Aims. While XRBs ...evolve rapidly and several sources have undergone a few complete cycles from quiescence to an outburst and back, most AGN remain in the same state over periods of years and decades, due to their longer characteristic timescale proportional to their size. However, the study of the AGN spectral states is still possible with a large sample of sources. Multi-wavelength observations are needed for this purpose since the AGN thermal disc emission dominates in the ultraviolet energy range, while the up-scattered hot-corona emission is detected in X-rays. Methods. We compared simultaneous UV and X-ray measurements of AGN obtained by the XMM-Newton satellite. The non-thermal power-law flux was constrained from the 2−12 keV X-ray luminosity, while the thermal disc component was estimated from the UV flux at ≈ 2900 Å. The hardness (defined as a ratio between the X-ray and UV plus X-ray luminosity) and the total luminosity were used to construct the AGN state diagrams. For sources with reliable mass measurements, the Eddington ratio was used instead of the total luminosity. Results. The state diagrams show that the radio-loud sources have on average higher hardness, due to the lack of the thermal disc emission in the UV band, and have flatter intrinsic X-ray spectra. In contrast, the sources with high luminosity and low hardness are radio-quiet AGN with the UV spectrum consistent with the multi-temperature thermal disc emission. The hardness-Eddington ratio diagram reveals that the average radio-loudness is stronger for low-accreting sources, while it decreases when the accretion rate is close to the Eddington limit. Conclusions. Our results indicate that the general properties of AGN accretion states are similar to those of XRBs. This suggests that the AGN radio dichotomy of radio-loud and radio-quiet sources can be explained by the evolution of the accretion states.
Recent X-ray observations show absorbing winds with velocities up to mildly relativistic values of the order of ∼0.1c 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 ≃ 0.4c, with mean and median values of v
out ≃ 0.133c and v
out ≃ 0.117c, respectively. The material is highly ionized, with an average ionization parameter of logξ ≃ 4.5 erg s−1 cm, and the column densities are larger than N
H > 1022 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.
We present a sample of 8 nearby Seyfert 2 galaxies observed by HST and Chandra. All of the sources present soft X-ray emission which is coincident in extension and overall morphology with the O iii ...emission. The spectral analysis reveals that the soft X-ray emission of all the objects is likely to be dominated by a photoionized gas. This is strongly supported by the 190 ks combined XMM-Newton/RGS spectrum of Mrk 3, which different diagnostic tools confirm as being produced in a gas in photoionization equilibrium with an important contribution from resonant scattering. We tested with the code cloudy a simple scenario where the same gas photoionized by the nuclear continuum produces both the soft X-ray and the O iii emission. Solutions satisfying the observed ratio between the two components exist, and require the density to decrease with radius roughly like r-2, similarly to what often found for the Narrow Line Region.
ABSTRACT
We present the results of the latest NuSTAR monitoring campaign of the Compton-thick Seyfert 2 galaxy NGC 1068, composed of four ∼50 ks observations performed between 2017 July and 2018 ...February to search for flux and spectral variability on time-scales from 1 to 6 months. We detect one unveiling and one eclipsing event with time-scales less than 27 and 91 d, respectively, ascribed to Compton-thick material with NH = (1.8 ± 0.8) × 1024 and ≥ (2.4 ± 0.5) × 1024 cm−2 moving across our line of sight. This gas is likely located in the innermost part of the torus or even further inward, thus providing further evidence of the clumpy structure of the circumnuclear matter in this source. Taking advantage of simultaneous Swift–XRT observations, we also detected a new flaring ULX, at a distance d ∼ 30 arcsec (i.e. ∼2 kpc) from the nuclear region of NGC 1068, with a peak X-ray intrinsic luminosity of (3.0 ± 0.4) × 1040 erg s−1 in the 2–10 keV band.
We present results from a homogeneous analysis of the broad-band 0.3–10 keV CCD resolution as well as of the soft X-ray high-resolution grating spectra of a hard X-ray flux-limited sample of 26 ...Seyfert galaxies observed with XMM–Newton. Our goal is to characterize warm absorbers (WAs) along the line of sight to the active nucleus. We significantly detect WAs in 65 per cent of the sample sources. Our results are consistent with WAs being present in at least half of the Seyfert galaxies in the nearby Universe, in agreement with previous estimates. We find a gap in the distribution of the ionization parameter in the range 0.5 < log ξ < 1.5 which we interpret as a thermally unstable region for WA clouds. This may indicate that the WA flow is probably constituted by a clumpy distribution of discrete clouds rather than a continuous medium. The distribution of the WA column densities for the sources with broad Fe Kα lines are similar to those sources which do not have broadened emission lines. Therefore, the detected broad Fe Kα emission lines are bona fide and not artefacts of ionized absorption in the soft X-rays. The WA parameters show no correlation among themselves, with the exception of the ionization parameter versus column density. The shallow slope of the log ξ versus log v
out linear regression (0.12 ± 0.03) is inconsistent with the scaling laws predicted by radiation or magnetohydrodynamic-driven winds. Our results also suggest that WA and ultra fast outflows do not represent extreme manifestation of the same astrophysical system.
ABSTRACT Winds outflowing from active galactic nuclei (AGNs) may carry significant amounts of mass and energy out to their host galaxies. In this paper we report the detection of a sub-relativistic ...outflow observed in the narrow line Seyfert 1 galaxy IRAS 17020+4544 as a series of absorption lines corresponding to at least five absorption components with an unprecedented wide range of associated column densities and ionization levels and velocities in the range of 23,000-33,000 km s−1, detected at X-ray high spectral resolution (E/ΔE ∼ 1000) with the ESA's observatory XMM-Newton. The charge states of the material constituting the wind clearly indicate a range of low to moderate ionization states in the outflowing gas and column densities that are significantly lower than observed in highly ionized ultra-fast outflows. We estimate that at least one of the outflow components may carry sufficient energy to substantially suppress star formation and heat the gas in the host galaxy. IRAS 17020+4544 therefore provides an interesting example of feedback by a moderately luminous AGN that is hosted in a spiral galaxy, a case barely envisaged in most evolution models, which often predict that feedback processes take place in massive elliptical galaxies hosting luminous quasars in a post-merger phase.
We present a NuSTAR and XMM–Newton monitoring campaign in 2014/2015 of the Compton-thick Seyfert 2 galaxy, NGC 1068. During the 2014 August observation, we detect with NuSTAR a flux excess above ...20 keV (32 ± 6 per cent) with respect to the 2012 December observation and to a later observation performed in 2015 February. We do not detect any spectral variation below 10 keV in the XMM–Newton data. The transient excess can be explained by a temporary decrease of the column density of the obscuring material along the line of sight (from N
H ≃ 1025 cm−2 to N
H = 6.7 ± 1.0 × 1024 cm−2), which allows us for the first time to unveil the direct nuclear radiation of the buried active galactic nucleus in NGC 1068 and to infer an intrinsic 2–10 keV luminosity L
$_{\rm X}=7^{+7}_{-4} \times 10^{43}$
erg s−1.
We discuss the X-ray properties of 49 local ($z<0.035$) Seyfert 2 galaxies with HST/WFC2 high-resolution optical coverage. It includes the results of 26 still unpublished Chandra and XMM-Newton ...observations, which yield 25 (22) new X-ray detections in the 0.5–2 keV (2–10 keV) energy band. Our sample covers a range in the 2–10 keV observed flux, F2-10, from $3 \times 10^{-11}$ to $6 \times 10^{-15}$ erg cm-2 s-1. The percentage of objects that are likely obscured by Compton-thick matter (column density, $N_{\rm H} \ge \sigma_t^{-1} \simeq 1.6 \times 10^{24}$ cm-2) is $\simeq$50%, and reaches $\simeq$80% for $\log\, (F_{2-10}) < 12.3$. Hence, Kα fluorescent iron lines with large Equivalent Width (${\it EW} > 0.6$ keV) are common in our sample (6 new detections at a confidence level ≥2σ). They are explained as due to reflection off the illuminated side of optically thick material. We confirm a correlation between the presence of a ~100-pc scale nuclear dust in the WFC2 images and Compton-thin obscuration. We interpret this correlation as due to the large covering fraction of gas associated with the dust lanes. The X-ray spectra of highly obscured AGN invariably present a prominent soft excess emission above the extrapolation of the hard X-ray component. This soft component can account for a very large fraction of the overall X-ray energy budget. As this component is generally unobscured – and therefore likely produced in extended gas structures – it may lead to a severe underestimation of the nuclear obscuration in $z \sim 1$ absorbed AGN, if standard X-ray colors are used to classify them. As a by-product of our study, we report the discovery of a soft X-ray, luminous ($\simeq$7$\,\times\, 10^{40}$ erg s-1) halo embedding the interacting galaxy pair Mkn 266.
Context. Recent XMM-Newton observations have revealed that IRAS 17020+4544 is a very unusual example of black hole wind-produced feedback by a moderately luminous AGN in a spiral galaxy. Aims. Since ...the source is known to be a radio emitter, we investigated the presence and the properties of a non-thermal component. Methods. We observed IRAS 17020+4544 with the Very Long Baseline Array at 5, 8, 15, and 24 GHz within a month of the 2014 XMM-Newton observations. We further analysed archival data taken in 2000 and 2012. Results. We detect the source at 5 GHz and on short baselines at 8 GHz. At 15 and 24 GHz, the source is below our baseline sensitivity for fringe fitting, indicating a lack of prominent compact features. The morphology is that of an asymmetric double, with significant diffuse emission. The spectrum between 5 and 8 GHz is rather steep (S(ν) ~ ν− (1.0 ± 0.2)). Our reanalysis of the archival data at 5 and 8 GHz provides results consistent with the new observations, suggesting that flux density and structural variability are not important in this source. We put a limit on the separation speed between the main components of <0.06c. Conclusions. IRAS 17020+4544 shows interesting features of several classes of objects: its properties are typical of compact steep spectrum sources, low power compact sources, and radio-emitting narrow line Seyfert 1 galaxies. However, it cannot be classified in any of these categories, and remains a one-of-a-kind object.
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