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Context.Numerical simulations of MHD accretion flows in the vicinity of a supermasssive black hole provide useful insights in to the problem of why and how systems – such as the Galactic center – are underluminous and variable. In particular, the simulations indicate that low angular-momentum accretion flow is highly variable both quantitatively and qualitatively. This variability and a relatively low mass-accretion rate are caused by interplay between a rotationally supported torus, its outflow, and a nearly non-rotating inflow.

We present a Chandra-LETGS observation of the Seyfert 1 galaxy Mrk 279. This observation was simultaneous with HST-STIS and FUSE observations, in the context of a multiwavelength study of this source. The Chandrapointings were spread over ten days for a total exposure time of ~360 ks. The maximal continuum flux variation is of the order of 30%. The spectrum of Mrk 279shows evidence of broad emission features, especially at the wavelength of the O viitriplet. We quantitatively explore the possibility that this emission is produced in the broad line region (BLR). We modeled the broad UV emission lines seen in the FUSE and HST-STIS spectra following the “locally optimally emitting cloud” approach. This method considers the emission from BLR as arising from “clouds” with a wide range of densities and distances from the source. We find that the X-ray lines luminosity derived from the best fit BLR model match the observed X-ray features, suggesting that the gas producing the UV lines is sufficient to account for the X-ray emission. The spectrum is absorbed by ionized gas whose total column density is ~5 $\times$1020cm-2. The absorption spectrum can be modeled by two distinct gas components (log $\xi\sim 0.47$and 2.49, respectively) both showing a significant outflow velocity. However, the data also allow for the presence of intermediate ionization components. The distribution of the column densities of such extra components as a function of the ionization parameter is not consistent with a continuous, power-law like, absorber, suggesting a complex structure for the gas outflow for Mrk 279.

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 $\ion{O}{v}$transitions. $\ion{O}{v}$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 $\ion{O}{v}$, 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.

Context.X-ray studies of active galactic nuclei (AGN) with powerful nuclear winds are important for constraining the physics of the inner accretion/ejection flow around supermassive black holes (SMBHs) and for understanding the impact of such winds on the AGN environment.

We present an analysis of the AGN broad-line regions of 6 powerful radio galaxies at z~ 2 (HzRGs), which is part of a study of a sample of 50 HzRGs with rest-frame optical imaging spectroscopy obtained at the VLT. In 6 galaxies we detect luminous (ℒ(Hα)  = few  × 1044erg s-1), spatially unresolved, broad (FWHM≥ 10 000 km s-1) Hαline emission from the nucleus (HαBLRs), consistent with broad-line regions of supermassive black holes with masses of few  ×  109M⊙and accretion luminosities of a few percent of the Eddington luminosity. In two galaxies we also detect HβBLRs, suggesting relatively low extinction of AV~ 1 mag, which agrees with constraints from X-ray observations. Overall, we find HαBLRs in  ~20% of the galaxies where Hαis observed. By relating black hole and bulge mass, we find a possible offset towards higher black-hole masses of at most  ~0.6 dex relative to nearby galaxies at a given host mass, although each individual galaxy is within the scatter of the local relationship. If not entirely from systematic effects, this would then suggest that the masses of the host galaxies have increased by at most a factor   ≈4 since z~ 2 relative to the black-hole masses, perhaps through accretion of satellite galaxies or because of a time lag between star formation in the host galaxy and AGN fueling. We also compare the radiative and mechanical energy output (from jets) of our targets with predictions of recent models of “synthesis” or “grand unified” AGN feedback, which postulate that AGN with similar radiative and mechanical energy output rates to those found in our HzRGs may be nearing the end of their period of active growth. We discuss evidence that they may reach this stage at the same time as their host galaxies.