We present a spectral and imaging analysis of the XMM-Newton and Chandra observations of the Seyfert 2 galaxy ESO138-G001, with the aim of characterizing the circumnuclear material responsible for the soft (0.3-2.0 keV) and hard (5-10 keV) X-ray emis
sion. We confirm that the source is absorbed by Compton-thick gas. However, if a self-consistent model of reprocessing from cold toroidal material is used (MYTorus), a possible scenario requires the absorber to be inhomogenous, its column density along the line of sight being larger than the average column density integrated over all lines- of-sight through the torus. The iron emission line may be produced by moderately ionised iron (FeXII-FeXIII), as suggested by the shifted centroid energy and the low K{beta}/K{alpha} flux ratio. The soft X-ray emission is dominated by emission features, whose main excitation mechanism appears to be photoionisation, as confirmed by line diagnostics and the use of self-consistent models (CLOUDY).
NuSTAR observed the bright Compton-thin, narrow line Seyfert 1 galaxy, NGC 5506, for about 56 ks. In agreement with past observations, the spectrum is well fit by a power law with Gamma~1.9, a distant reflection component and narrow ionized iron line
s. A relativistically blurred reflection component is not required by the data. When an exponential high energy cutoff is added to the power law, a value of 720(+130,-190) keV (90% confidence level) is found. Even allowing for systematic uncertainties, we find a 3 sigma lower limit to the high-energy cutoff of 350 keV, the highest lower limit to the cutoff energy found so far in an AGN by NuSTAR.
MCG-6-30-15, at a distance of 37 Mpc (z=0.008), is the archetypical Seyfert 1 galaxy showing very broad Fe K$alpha$ emission. We present results from a joint NuSTAR and XMM-Newton observational campaign that, for the first time, allows a sensitive, t
ime-resolved spectral analysis from 0.35 keV up to 80 keV. The strong variability of the source is best explained in terms of intrinsic X-ray flux variations and in the context of the light bending model: the primary, variable emission is reprocessed by the accretion disk, which produces secondary, less variable, reflected emission. The broad Fe K$alpha$ profile is, as usual for this source, well explained by relativistic effects occurring in the innermost regions of the accretion disk around a rapidly rotating black hole. We also discuss the alternative model in which the broadening of the Fe K$alpha$ is due to the complex nature of the circumnuclear absorbing structure. Even if this model cannot be ruled out, it is disfavored on statistical grounds. We also detected an occultation event likely caused by BLR clouds crossing the line of sight.
We present simultaneous XMM-Newton and NuSTAR observations of the `bare Seyfert 1 galaxy, Ark 120, a system in which ionized absorption is absent. The NuSTAR hard X-ray spectral coverage allows us to constrain different models for the excess soft X-r
ay emission. Among phenomenological models, a cutoff power law best explains the soft X-ray emission. This model likely corresponds to Comptonization of the accretion disk seed UV photons by a population of warm electrons: using Comptonization models, a temperature of ~0.3 keV and an optical depth of ~13 are found. If the UV-to-X-ray optxagnf model is applied, the UV fluxes from the XMM-$Newton$ Optical Monitor suggest an intermediate black hole spin. Contrary to several other sources observed by NuSTAR, no high energy cutoff is detected, with a lower limit of 190 keV.
We present the XMM-Newton RGS and EPIC pn spectra of a long (simeq 100 ks) observation of one of the soft X-ray brightest Compton-thick Seyfert 2 galaxies, NGC 424. As a first step, we performed a phenomenological analysis of the data to derive the p
roperties of all the spectral components. On the basis of these results, we fitted the spectra with self-consistent photoionisation models, produced with CLOUDY. The high-energy part of the spectrum is dominated by a pure neutral Compton reflection component and a neutral iron K-alpha line, together with K-alpha emission from neutral Ni, suggesting a significant Ni/Fe overabundance. The soft X-ray RGS spectrum comes mostly from line emission from H-like and He-like C, N, O, and Ne, as well as from the Fe L-shell. The presence of narrow RRC from O VIII, O VII, and C VI, the last two with resolved widths corresponding to temperatures around 5-10 eV, is a strong indication of a gas in photoionisation equilibrium, as confirmed by the prevalence of the forbidden component in the O VII triplet. Two gas phases with different ionisation parameters are needed to reproduce the spectrum with a self-consistent photoionisation model, any contribution from a gas in collisional equilibrium being no more than 10% of the total flux in the 0.35-1.55 keV band. When this self-consistent model is applied to the 0.5-10 keV band of the EPIC pn spectrum, a third photoionised phase is needed to account for emission lines with higher ionisation potential, although K-alpha emission from S XV and Fe XXVI remains under-predicted.
