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Context.Mrk 841is a bright Seyfert 1 galaxy known to harbor a strong soft excess and a variable Kαiron line. Historical UV, X and γ-rays observations show clear variation of its spectrum in flux and in shape on a monthly time scale.

Context.This paper reports on a partially simultaneous observation of the bright Seyfert 1 Galaxy Mrk 590, performed by XMM-Newton and Chandra.

The observation of the Narrow-Line Seyfert 1 galaxy IRAS 13349+2438 performed by XMM-Newton European Photon Imaging Camera between 0.3-10 keV, is presented here. The broadband spectrum of the source is dominated at low energies ($E \leq2$keV) by a strong excess of emission and by complex emission/absorption features between ~5.5-8.0 keV. The soft X-ray spectrum is consistent with ionized absorption found by the Reflection Grating Spectrometer (Sako et al. 2001a). We focus on the 2-10 keV spectrum which shows clear evidence for a broad, complex FeKαline, previously unseen by ASCA, and for an Fe K-shell edge detected at ~7.3-7.4 keV (rest-frame). The presence of this edge could be explained by either partial covering or ionized/relativistic reflection models, with the latter being preferred and with a resulting power law slope of $\Gamma \sim 2.2$. The line profile is complex, with a broad bump between ~5.5-6.5 keV and a narrow emission line at ~7 keV, separated by a sharp drop at ~6.8 keV. This profile is compatible with two possible scenarios: i) a broad, ionized and gravitationally redshifted Laor diskline plus a narrow and ionized emission line; ii) a broad, ionized and single Schwarzschild (double-peaked) diskline with a superimposed narrow absorption line.

Context.Markarian 509 and Markarian 841 are two bright Seyfert 1 galaxies with X-ray spectra characterised by a strong soft excess and a variable Fe Kαline, as shown by several X-ray observatories in the past.

We study the X-ray emission of a representative sample of 27 local luminous infrared galaxies (LIRGs). The median IR luminosity of our sample is log LIR/L⊙= 11.2, therefore the low-luminosity end of the LIRG class is well represented. We used new XMM-Newtondata as well as Chandra and XMM-Newtonarchive data. The soft X-ray (0.5–2 keV) emission of most of the galaxies (>80%), including LIRGs hosting a Seyfert 2 nucleus, is dominated by star-formation-related processes. These LIRGs follow the star-formation rate (SFR) versus soft X-ray luminosity correlation observed in local starbursts. We find that  ~15% of the non-Seyfert LIRGs (3 out of 20) have an excessively hard X-ray emission relative to that expected from star-formation, which might indicate the presence of an obscured AGN. The rest of the non-Seyfert LIRGs follow the SFR versus hard X-ray (2–10 keV) luminosity correlation of local starbursts. The non-detection of the 6.4 keV Fe Kαemission line in the non-Seyfert LIRGs allows us to put an upper limit on the bolometric luminosity of an obscured AGN, Lbol<1043erg s-1. That is, if these galaxies were hosting a low-luminosity AGN, its contribution to the total luminosity would be less than 10%. Finally we estimate that the AGN contribution to the total luminosity for our sample of local LIRGs is between 7% and 10%.

Context.In about half of the Seyfert galaxies, the X-ray emission is absorbed by an optically thin, ionized medium, the so-called “warm absorber”, whose origin and location is still a matter of debate.

Context.Spectroscopy of X-ray emission lines emitted from accretion discs around supermassive black holes is one of the most powerful probes of the accretion flow physics and geometry, while also providing in principle observational constraints on the black hole spin. Previous studies have suggested that relativistically broadened line profiles are fairly common in nearby unobscured Seyfert galaxies. Their strength, as parametrised by the equivalent width (EW) against the total underlying continuum, spans a range of almost two orders of magnitude.

Context.Accretion models predict that fluorescence lines broadened by relativistic effects should arise from reflection of X-ray emission onto the inner region of the accretion disc surrounding the central black hole of active galactic nuclei (AGN). The theory behind the origin of relativistic lines is well established, and observational evidence from a moderate number of sources seems to support the existence of these lines.

Context. Soft X-ray high resolution spectroscopy of obscured AGNs shows a complex soft X-ray spectrum dominated by emission lines of He and H-like transitions of elements from carbon to neon, as well as L-shell transitions due to iron ions.Aims. In this paper we characterize the XMM-Newton RGS spectrum of the Seyfert 1 galaxy NGC 4051 observed during a low flux state and infer the physical properties of the emitting and absorbing gas in the soft X-ray regime.Methods. X-ray high-resolution spectroscopy offers a powerful diagnostic tool because the observed spectral features strongly depend on the physical properties of matter (ionization parameter U, electron density ne, hydrogen column density NH), which in turn are tightly related to the location and size of the X-ray emitting clouds. We carried out a phenomenological study to identify the atomic transitions detected in the spectra. This study suggests that the spectrum is dominated by emission from a photoionized plasma. Then we used the photoionization code Cloudy to produce synthetic models for the emission line component and the warm absorber observed during phases of high intrinsic luminosity.Results. The low state spectrum cannot be described by a single photoionization component. A multi-ionization phase gas with an ionization parameter in the range of log U~ 0.63–1.90 and a column density log NH= 22.10–22.72 cm-2is required, while the electron density neremains unconstrained. A warm absorber medium is required by the fit with the parameters log U~ 0.85, log NH= 23.40 and log ne$\la$5. The model is consistent with an X-ray emitting region at a distance $\ga$5 × 10-2pc from the central engine.