Galaxy merging is widely accepted to be a key driving factor in galaxy formation and evolution, while the feedback from AGN is thought to regulate the BH-bulge coevolution and the star formation process. In this context, we focused on 1SXPSJ050819.8+
172149, a local (z=0.0175) Seyfert 1.9 galaxy (L_bol~4x10^43 ergs/s). The source belongs to an IR-luminous interacting pair of galaxies, characterized by a luminosity for the whole system (due to the combination of star formation and accretion) of log(L_IR/L_sun)=11.2. We present the first detailed description of the 0.3-10keV spectrum of 1SXPSJ050819.8+172149, monitored by Swift with 9 pointings performed in less than 1 month. The X-ray emission of 1SXPSJ050819.8+172149 is analysed by combining all the Swift pointings, for a total of ~72ks XRT net exposure. The averaged Swift-BAT spectrum from the 70-month survey is also analysed. The slope of the continuum is ~1.8, with an intrinsic column density NH~2.4x10^22 cm-2, and a deabsorbed luminosity L(2-10keV)~4x10^42 ergs/s. Our observations provide a tentative (2.1sigma) detection of a blue-shifted FeXXVI absorption line (rest-frame E~7.8 keV), suggesting the discovery for a new candidate powerful wind in this source. The physical properties of the outflow cannot be firmly assessed, due to the low statistics of the spectrum and to the observed energy of the line, too close to the higher boundary of the Swift-XRT bandpass. However, our analysis suggests that, if the detection is confirmed, the line could be associated with a high-velocity (vout~0.1c) outflow most likely launched within 80r_S. To our knowledge this is the first detection of a previously unknown ultrafast wind with Swift. The high NH suggested by the observed equivalent width of the line (EW~ -230eV, although with large uncertainties), would imply a kinetic output strong enough to be comparable to the AGN bolometric luminosity.
Although absorbed quasars are extremely important for our understanding of the energetics of the Universe, the main physical parameters of their central engines are still poorly known. In this work we present and study a complete sample of 14 quasars
(QSOs) that are absorbed in the X-rays (column density NH>4x10^21 cm-2 and X-ray luminosity L(2-10 keV)>10^44 ergs/s; XQSO2) belonging to the XMM-Newton Bright Serendipitous Survey (XBS). From the analysis of their ultraviolet-to-mid-infrared spectral energy distribution we can separate the nuclear emission from the host galaxy contribution, obtaining a measurement of the fundamental nuclear parameters, like the mass of the central supermassive black hole and the value of Eddington ratio, lambda_Edd. Comparing the properties of XQSO2s with those previously obtained for the X-ray unabsorbed QSOs in the XBS, we do not find any evidence that the two samples are drawn from different populations. In particular, the two samples span the same range in Eddington ratios, up to lambda_Edd=0.5; this implies that our XQSO2s populate the forbidden region in the so-called effective Eddington limit paradigm. A combination of low grain abundance, presence of stars inwards of the absorber, and/or anisotropy of the disk emission, can explain this result.
We present the results of the Suzaku observation of the Seyfert 2 galaxy NGC 4507. This source is one of the X-ray brightest Compton-thin Seyfert 2s and a candidate for a variable absorber. Suzaku caught NGC 4507 in a highly absorbed state characteri
sed by a high column density (NH sim8 x10^23 cm^-2), a strong reflected component (Rsim 1.9) and a high equivalent width Fe K alpha emission line (EWsim 500 eV). The Fe K alpha emission line is unresolved at the resolution of the Suzaku CCDs (sigma < 30 eV or FWHM < 3000 km s^-1) and most likely originates in a distant absorber. The Fe K beta emission line is also clearly detected and its intensity is marginally higher than the theoretical value for low ionisation Fe. A comparison with previous observations performed with XMM-Newton and BeppoSAX reveals that the X-ray spectral curvature changes on a timescale of a few months. We analysed all these historical observations, with standard models as well as with a most recent model for a toroidal reprocessor and found that the main driver of the observed 2-10 keV spectral variability is a change of the line-of-sight obscuration, varying from sim4x10^23 cm^-2 to sim9 x 10^23 cm^-2. The primary continuum is also variable, although its photon index does not appear to vary, while the Fe K alpha line and reflection component are consistent with being constant across the observations. This suggests the presence of a rather constant reprocessor and that the observed line of sight NH variability is either due to a certain degree of clumpiness of the putative torus or due to the presence of a second clumpy absorber.
We present the analysis of Suzaku and XMM-Newton observations of the broad-line radio galaxy (BLRG) 3C 111. Its high energy emission shows variability, a harder continuum with respect to the radio quiet AGN population, and weak reflection features. S
uzaku found the source in a minimum flux level; a comparison with the XMM-Newton data implies an increase of a factor of 2.5 in the 0.5-10 keV flux, in the 6 months separating the two observations. The iron K complex is detected in both datasets, with rather low equivalent width(s). The intensity of the iron K complex does not respond to the change in continuum flux. An ultra-fast, high-ionization outflowing gas is clearly detected in the XIS data; the absorber is most likely unstable. Indeed, during the XMM-Newton observation, which was 6 months after, the absorber was not detected. No clear roll-over in the hard X-ray emission is detected, probably due to the emergence of the jet as a dominant component in the hard X-ray band, as suggested by the detection above ~ 100 keV with the GSO on-board Suzaku, although the present data do not allow us to firmly constrain the relative contribution of the different components. The fluxes observed by the gamma-ray satellites CGRO and Fermi would be compatible with the putative jet component if peaking at energies E ~ 100 MeV. In the X-ray band, the jet contribution to the continuum starts to be significant only above 10 keV. If the detection of the jet component in 3C 111 is confirmed, then its relative importance in the X-ray energy band could explain the different observed properties in the high-energy emission of BLRGs, which are otherwise similar in their other multiwavelength properties. Comparison between X-ray and gamma-ray data taken at different epochs suggests that the strong variability observed for 3C 111 is probably driven by a change in the primary continuum.
This paper reports on two XMM-Newton observations of the Seyfert 1 Galaxy H0557-385 obtained in 2006, which show the source at an historical low flux state, more than a factor of 10 lower than a previous XMM-Newton look in 2002. The low flux spectrum
presents a strong Fe Kalpha line associated to a Compton reflection continuum. An additional spectral line around 6.6 keV is required to fit Kalpha emission from Fe XXV. The spectral curvature below 6 keV implies obscuration by neutral gas with a column density of 8*10^{23}cm^{-2} partially covering the primary emission, which still contributes for a few percent of the soft X-ray emission. Absorption by ionised material on the line of sight is required to fit the deep trough below 1 keV. The comparison of the two spectral states shows that the flux transition is to be ascribed entirely to intervening line-of-sight clouds with high column density.
This paper was withdrawn due to a misidentification of the source.
PG1535+547 is a bright NLS1 galaxy, whose high energy emission shows strong variability in shape and flux. ROSAT data classified it as soft X-ray weak QSO (objects whose X-ray-to-optical flux ratio is smaller than in typical QSO): their X-ray spectra
are often characterized by highly ionized, complex absorbers and/or reflection from the disk, whose relative importance is currently debated. In both cases, the presence of such features implies that we are looking at matter located in the innermost regions of the AGN. In this paper we want to clarify the nature of the X-ray emission of PG1535+547, and constrain the physical properties of regions where the emission originates. We present new XMM observations, from which we obtained 2 spectra separated by about 1 week, that we compare with a previous XMM observation. The data support the complex and variable nature of the X-ray emission. The broad band flux increases by a factor ~2.3 in 3 years, and then decreases by a factor ~1.3 in about 1 week. In the new EPIC spectra strong absorption features at E<3keV and a complex spectral shape in the Fe line energy range are evident, coupled with a drop in the emission at higher energies. We describe all the states assuming either a warm absorber plus a relativistically blurred ionized reflection, or a two-phase warm absorber partially covering the source plus a scattered component. The variability is ascribed to the warm absorbers, that vary their physical properties on timescales of years and days. In the reflection scenario all the states require a high fraction of reflection. The strong variability in the X-ray band opposed to a more constant optical emission implies that PG1535+547 can not actually be classified as a soft X-ray weak AGN.
