arXiv subjects

E. Costantini

Publications and source records attributed to E. Costantini.

At least 91 records · Page 5Linked to original sources

arXiv2013

The Hot and Energetic Universe: Astrophysics of feedback in local AGN

Understanding the astrophysics of feedback in active galactic nuclei (AGN) is key to understanding the growth and co-evolution of supermassive black holes and galaxies. AGN-driven winds/outflows are potentially the most effective way of transporting energy and momentum from the nuclear scales to the host galaxy, quenching star formation by sweeping away the gas reservoir. Key questions in this field are: 1) how do accretion disks around black holes launch winds/outflows, and how much energy do these carry? 2) How are the energy and metals accelerated in winds/outflows transferred and deposited into the circumgalactic medium? X-ray observations are a unique way to address these questions because they probe the phase of the outflows which carries most of the kinetic energy. We show how a high throughput, high spectral resolution instrument like the X-ray Integral Field Unit (X-IFU) on Athena+ will allow us to address these questions by determining the physical parameters (ionization state, density, temperature, abundances, velocities, geometry, etc.) of the outflows on a dynamical time-scale, in a broad sample of nearby bright AGN. The X-IFU will also allow direct spectral imaging of the impact of these winds on the host galaxy for local AGN, forming a template for understanding AGN at higher redshifts where wind shocks cannot be resolved.

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arXiv2013

The Hot and Energetic Universe: The astrophysics of supernova remnants and the interstellar medium

The study of both supernova remnants and the hot and cold phases of the interstellar medium are essential for understanding the final stages of stellar evolution and their feedback on the evolution of galaxies through injection of energy and heavy elements. These studies are also crucial for understanding the physics of supernovae, their cosmological implication, and the origin of galactic cosmic rays. The unique capabilities of Athena+ will allow us to explore a new parameter space. Spatially-resolved high-resolution spectroscopy using Athena+ X-IFU of young remnants will allow to characterize individual parcels of ejected material in the line of sight in terms of kinematics, ionization and composition, providing access to the three dimensional geometry of the explosion. Athena+ will also allow studying shock physics and particle acceleration in supernova remnants, as well as their interaction with their environment. Athena+ X-IFU will also characterize the ionization mechanisms competing in forming the complex structures of the hot interstellar medium, likely to keep the echo of past star formation activity, both in our Galaxy and nearby ones. For the first time the dust and gas of the densest cold medium, like in the Galactic Centre environment, will be studied. Athena+ X-IFU will observe, along with the Mg K and Si K edges, which are the main tracers of the silicates content of the ISM, the Fe K edge with unprecedented sensitivity and energy-resolution. This will allow us to study for the first time the nature of Fe-bearing dust in such regions.

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arXiv2013

Simultaneous XMM-Newton and HST-COS observation of 1H0419-577: the absorbing and emitting ionized gas

In this paper we analyze the X-ray, UV and optical data of the Seyfert 1.5 galaxy 1H0419-577, with the aim of detecting and studying an ionized-gas outflow. The source was observed simultaneously in the X-rays with XMM and in the UV with HST-COS. Optical data were also acquired with the XMM Optical Monitor. We detected a thin, lowly ionized warm absorber (log xi ~ 0.03, log NH ~19.9 cm^-2) in the X-ray spectrum, consistent to be produced by the same outflow already detected in the UV. Provided the gas density estimated in the UV, the outflow is consistent to be located in the host galaxy, at ~ kpc scale. Narrow emission lines were detected in the X-rays, in the UV and also in the optical spectrum. A single photoionized-gas model cannot account for all the narrow lines emission, indicating that the narrow line region is probably a stratified environment, differing in density and ionization. X-ray lines are unambiguously produced in a more highly ionized gas phase than the one emitting the UV lines. The analysis suggests also that the X-ray emitter may be just a deeper portion of the same gas layer producing the UV lines. Optical lines are probably produced in another, disconnected gas system. The different ionization condition, and the ~ pc scale location suggested by the line width for the narrow lines emitters, argue against a connection between the warm absorber and the narrow line region in this source.

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arXiv2013

ISM composition through X-ray spectroscopy of LMXBs

The diffuse interstellar medium (ISM) is an integral part of the evolution of the entire Galaxy. Metals are produced by stars and their abundances are the direct testimony of the history of stellar evolution. However, the interstellar dust composition is not well known and the total abundances are yet to be accurately determined. We probe ISM dust composition, total abundances, and abundance gradients through the study of interstellar absorption features in the high-resolution X-ray spectra of Galactic low-mass X-ray binaries (LMXBs). We use high-quality grating spectra of nine LMXBs taken with XMM-Newton. We measure the column densities of O, Ne, Mg, and Fe with an empirical model and estimate the Galactic abundance gradients. The column densities of the neutral gas species are in agreement with those found in the literature. Solids are a significant reservoir of metals like oxygen and iron. Respectively, 15-25 % and 65-90 % of the total amount of O I and Fe I is found in dust. The dust amount and mixture seem to be consistent along all the lines-of-sight (LOS). Our estimates of abundance gradients and predictions of local interstellar abundances are in agreement with those measured at longer wavelengths. Our work shows that X-ray spectroscopy is a very powerful method to probe the ISM. For instance, on a large scale the ISM appears to be chemically homogeneous showing similar gas ionization ratios and dust mixtures. The agreement between the abundances of the ISM and the stellar objects suggests that the local Galaxy is also chemically homogeneous.

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arXiv2012

Multiwavelength campaign on Mrk 509 XII. Broad band spectral analysis

(Abridged) The simultaneous UV to X-rays/gamma rays data obtained during the multi-wavelength XMM/INTEGRAL campaign on the Seyfert 1 Mrk 509 are used in this paper and tested against physically motivated broad band models. Each observation has been fitted with a realistic thermal comptonisation model for the continuum emission. Prompted by the correlation between the UV and soft X-ray flux, we use a thermal comptonisation component for the soft X-ray excess. The UV to X-rays/gamma-rays emission of Mrk 509 can be well fitted by these components. The presence of a relatively hard high-energy spectrum points to the existence of a hot (kT~100 keV), optically-thin (tau~0.5) corona producing the primary continuum. On the contrary, the soft X-ray component requires a warm (kT~1 keV), optically-thick (tau~15) plasma. Estimates of the amplification ratio for this warm plasma support a configuration close to the "theoretical" configuration of a slab corona above a passive disk. An interesting consequence is the weak luminosity-dependence of its emission, a possible explanation of the roughly constant spectral shape of the soft X-ray excess seen in AGNs. The temperature (~ 3 eV) and flux of the soft-photon field entering and cooling the warm plasma suggests that it covers the accretion disk down to a transition radius $R_{tr}$ of 10-20 $R_g$. This plasma could be the warm upper layer of the accretion disk. On the contrary the hot corona has a more photon-starved geometry. The high temperature ($\sim$ 100 eV) of the soft-photon field entering and cooling it favors a localization of the hot corona in the inner flow. This soft-photon field could be part of the comptonised emission produced by the warm plasma. In this framework, the change in the geometry (i.e. $R_{tr}$) could explain most of the observed flux and spectral variability.

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arXiv2012

Multiwavelength campaign on Mrk 509: Reverberation of the Fe Kalpha line

We report on a detailed study of the Fe K emission/absorption complex in the nearby, bright Seyfert 1 galaxy Mrk 509. The study is part of an extensive XMM-Newton monitoring consisting of 10 pointings (~60 ks each) about once every four days, and includes also a reanalysis of previous XMM-Newton and Chandra observations. Mrk 509 shows a clear (EW=58 eV) neutral Fe Kalpha emission line that can be decomposed into a narrow (sigma=0.027 keV) component (found in the Chandra HETG data) plus a resolved (sigma=0.22 keV) component. We find the first successful measurement of a linear correlation between the intensity of the resolved line component and the 3-10 keV flux variations on time-scales of years down to a few days. The Fe Kalpha reverberates the hard X-ray continuum without any measurable lag, suggesting that the region producing the resolved Fe Kalpha component is located within a few light days-week (r<~10^3 rg) from the Black Hole (BH). The lack of a redshifted wing in the line poses a lower limit of >40 rg for its distance from the BH. The Fe Kalpha could thus be emitted from the inner regions of the BLR, i.e. within the ~80 light days indicated by the Hbeta line measurements. In addition to these two neutral Fe Kalpha components, we confirm the detection of weak (EW~8-20 eV) ionised Fe K emission. This ionised line can be modeled with either a blend of two narrow FeXXV and FeXXVI emission lines or with a single relativistic line produced, in an ionised disc, down to a few rg from the BH. Finally, we observe a weakening/disappearing of the medium and high velocity high ionisation Fe K wind features found in previous XMM-Newton observations. This campaign has made possible the first reverberation measurement of the resolved component of the Fe Kalpha line, from which we can infer a location for the bulk of its emission at a distance of r~40-1000 rg from the BH.

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arXiv2012

Multiwavelength campaign on Mrk 509 IX. The Galactic foreground

The diffuse gas in and nearby the Milky Way plays an important role in the evolution of the entire Galaxy. It has a complex structure characterized by neutral, weakly and highly ionized gas, dust, and molecules. We probe this gas through the observation of its absorption lines in the high-energy spectra of background sources. We use high-quality spectra of AGN Mrk 509, located at high Galactic latitudes obtained with XMM-Newton, HST and FUSE. We use advanced absorption models consisting of photo- and collisional-ionization. We constrain the column density ratios of the different phases of the interstellar medium (ISM) and measure the abundances of C, N, O, Ne, Mg, Al, Si, S, and Fe. We detect seven discrete interstellar clouds with different velocities. One is a typical low-velocity cloud (LVC) and three belong to the family of the intermediate-velocity clouds (IVCs) found near the Galactic disk. These four clouds show large deviation from Solar abundances in the gas phase, mostly caused by dust depletion. The other three clouds are ionized high-velocity clouds (HVCs) and are located either in the Galactic environment or in the Local Group halo as suggested by the signatures of collisional ionization. The similar abundances and ionization structure of the HVCs suggest a common location and origin: they might belong to the remainder of an extragalactic cloud which was captured by the Galaxy. We have shown that combined UV / X-ray spectroscopy is a powerful tool to investigate the ISM. In common Galactic clouds, like LVCs and IVCs, the ISM shows a complex structure consisting of at least three different temperature phases.

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arXiv2012

Multiwavelength campaign on Mrk 509 VIII. Location of the X-ray absorber

The bright Seyfert 1 galaxy Mrk 509 was monitored by XMM-Newton and other satellites in 2009 to constrain the location of the outflow. We have studied the response of the photoionised gas to changes in the ionising flux produced by the central regions. We used the 5 discrete ionisation components A-E detected in the time-averaged spectrum taken with the RGS. Using the ratio of fluxed EPIC and RGS spectra, we put tight constraints on the variability of the absorbers. Monitoring with the Swift satellite started 6 weeks before the XMM-Newton observations, allowing to use the ionising flux history and to develop a model for the time-dependent photoionisation. Components A and B are too weak for variability studies, but the distance for component A is known from optical imaging of the [O III] line to be ~3 kpc. During the 5 weeks of the XMM-Newton observations we found no evidence of changes in the 3 X-ray dominant ionisation components C-E, despite a huge soft X-ray intensity increase of 60% in the middle of our campaign. This excludes high-density gas close to the black hole. Instead, using our time-dependent modelling, we find low density and derive firm lower limits to the distance of these components. Component D shows evidence for variability on longer time scales, yielding an upper limit to the distance. For component E we derive an upper limit to the distance based on the argument that the thickness of the absorbing layer must be less than its distance to the black hole. Combining these results, at the 90% confidence level, component C has a distance of >70 pc, component D between 5-33 pc, and component E >5 pc but smaller than 21-400 pc, depending upon modelling details. These results are consistent with the upper limits from the HST/COS observations of our campaign and point to an origin of the dominant, slow (v<1000 km/s) outflow components in the NLR or torus-region of Mrk 509.

astro-ph.CO↗

arXiv2012

Characterizing the UV and X-ray Outflow in Mrk 509

We observed Mrk 509 during the fall of 2009 during a multiwavelength campaign using XMM-Newton, Chandra, HST/COS, SWIFT, and Integral. The 600-ks XMM/RGS spectrum finds two kinematic components and a discrete distribution of ionized absorbers. Our high S/N COS spectrum detects additional complexity in the known UV absorption troughs from a variety of sources in Mrk 509, including the outflow from the active nucleus, the ISM and halo of the host galaxy, and infalling clouds or stripped gas from a merger that are illuminated by the AGN. The UV absorption only partially covers the emission from the AGN nucleus with covering fractions lower than those previously seen with STIS, and are comparable to those seen with FUSE. Given the larger apertures of COS and FUSE compared to STIS, we favor scattered light from an extended region near the AGN as the explanation for the partial covering. As observed in prior X-ray and UV spectra, the UV absorption has velocities comparable to the X-ray absorption, but the bulk of the ultraviolet absorption is in a lower ionization state with lower total column density than the gas responsible for the X-ray absorption. Variability compared to prior UV spectra lets us set limits on the location, density, mass flux, and kinetic energy of the outflowing gas. For component 1 at $-400 \rm km s^{-1}$, the kinetic energy flux of both the UV and the X-ray outflow is insufficient to have a significant impact on further evolution of the host galaxy.

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arXiv2011

XMM-Newton observation of 4U 1820-30: Broad band spectrum and the contribution of the cold interstellar medium

We present the analysis of the bright X-ray binary 4U 1820-30, based mainly on XMM-Newton-RGS data, but using complementary data from XMM-Epic, Integral, and Chandra-HETG, to investigate different aspects of the source. The broad band continuum is well fitted by a classical combination of black body and Comptonized emission. The continuum shape and the high flux of the source (L/L_Edd\sim0.16) are consistent with a "high state" of the source. We do not find significant evidence of iron emission at energies >=6.4 keV. The soft X-ray spectrum contain a number of absorption features. Here we focus on the cold-mildly ionized gas. The neutral gas column density is N_H\sim1.63x10^21 cm^-2. The detailed study of the oxygen and iron edge reveals that those elements are depleted, defined here as the ratio between dust and the total ISM cold phase, by a factor 0.20\pm0.02 and 0.87\pm0.14, respectively. Using the available dust models, the best fit points to a major contribution of Mg-rich silicates, with metallic iron inclusion. Although we find that a large fraction of Fe is in dust form, the fit shows that Fe-rich silicates are disfavored. The measured Mg:Fe ratio is 2.0\pm0.3. Interestingly, this modeling may point to a well studied dust constituent (GEMS), sometimes proposed as a silicate constituent in our Galaxy. Oxygen and iron are found to be slightly over- and under-abundant, respectively (1.23 and 0.85 times the solar value) along this line of sight. We also report the detection of two absorption lines, tentatively identified as part of an outflow of mildly ionized gas (ξ\sim-0.5) at a velocity of \sim1200 km/s.

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arXiv2011

Jets and outflows in Radio Galaxies: implications for AGN feedback

One of the main debated astrophysical problems is the role of the AGN feedback in galaxy formation. It is known that massive black holes have a profound effect on the formation and evolution of galaxies, but how black holes and galaxies communicate is still an unsolved problem. For Radio Galaxies, feedback studies have mainly focused on jet/cavity systems in the most massive and X-ray luminous galaxy clusters. The recent high-resolution detection of warm absorbers in some Broad Line Radio Galaxies allow us to investigate the interplay between the nuclear engine and the surrounding medium from a different perspective. We report on the detection of warm absorbers in two Broad Line Radio Galaxies, 3C 382 and 3C 390.3, and discuss the physical and energetic properties of the absorbing gas. Finally, we attempt a comparison between radio-loud and radio-quiet outflows.

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arXiv2011

Suzaku broad-band observations of the Seyfert 1 galaxies Mrk 509 and Mrk 841

We report an analysis and modelling of new Suzaku observations of the Seyfert 1 galaxies Mrk509 and Mrk841, taken between April and November 2006,for Mrk509,and between January and July 2007,for Mrk841,for a total exposure time of ~100 ks each.Data from XIS and HXD/PIN instruments,going from 0.5 to 60 keV,represent the highest spectral resolution simultaneous broad-band X-ray spectrum for these objects.We fitted the broad-band spectrum of both sources with a double Comptonisation model,adding neutral reflection from distant material and a two-phase warm absorber.We then studied the two competing models developed to explain the soft excess in terms of atomic processes:a blurred ionised disc reflection and an ionised absorption by a high velocity material.When fitting the data in the 3-10 keV range with a power law spectrum,and extrapolating this result to low energies,a soft excess is clearly observed below 2 keV:its strength is however weak compared to previous observations of both sources.A moderate hard excess is seen at energies greater than 10 keV,together with a neutral Fe K_a narrow emission line at E~6.4 keV and a broad Fe emission line.For Mrk509,the broad Fe emission line is required in all the three physical models in order to have a good fit to the data:this finding suggests that the blurred reflection model correctly describes the soft excess,but that it underestimates the broad Fe emission line.For the smeared absorption model,this suggests instead that the continuum spectrum absorbed by the outflowing gas should contain indeed a reflected component.For Mrk841,all three models that we tested provide a good fit to the data,and we cannot invalidate any of them.A broad emission line is required in the double Comptonisation and smeared absorption models,while the blurred reflection model consistently fits the broad-band spectrum,without adding any extra emission-line component.

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arXiv2011

Probing the unified model in NGC 7314

We present a study of the complex absorbed X-ray spectrum of the Narrow Line Seyfert 1 galaxy NGC 7314. We collected available public X-ray data from the archives of XMM-Newton, Suzaku, and ASCA. The spectra were analyzed using the fitting package SPEX. We find evidence of intrinsic neutral and ionized absorption in the XMM-Newton EPIC-pn spectrum. The ionized gas presents three significantly distinct ionization phases, although its kinematic properties could not be disentangled. At least two of these phases are also detected in the RGS spectrum, although with less significance due to the low statistics. The ASCA and Suzaku spectra show larger neutral absorption but no ionized gas signatures. The Fe Kalpha emission line is detected in all the observations and, additionally, Fe XXVI in the EPIC-pn spectrum, and Fe Kbeta in the Suzaku XIS spectrum. Using this observational evidence we construct a consistent picture of the geometry of the system in the context of the unified model of active galactic nuclei. The different observational properties are thus interpreted as clouds of neutral gas moving across our line of sight, which would be grazing a clumpy dusty torus.

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arXiv2011

Warm Absorber Energetics in Broad Line Radio Galaxies

We review the soft X-ray properties of 3C 390.3, 3C 120, 3C 382 and 3C 445, the only Broad Line Radio Galaxies (BLRG) for which good quality gratings data are currently available. The XMM-Newton/RGS data of 3C 390.3 and 3C 120 were re-analyzed searching for warm absorbers, already discovered in 3C 382 and 3C 445. We confirm the absence of ionized absorption features in 3C 120, but find signatures of outflowing gas (v_out \sim 10^2 km s^-1) in 3C 390.3. Its warm absorber (Logξ\sim 2 erg cm s^-1, N_H\sim 10^20 cm^-2), similar to that observed in 3C 382, is probably placed in the Narrow Line Regions. Its gas content is slower and less dense than the accretion disk wind discovered in 3C 445. Independently from the location of the warm gas, the outflowing masses (\dotM_out) of BLRGs are significantly (but improbably) predominant with respect to the accretion masses (\dotM_acc), suggesting a clumpy configuration of the warm absorber. However, even assuming overestimated values of \dotM_out, the kinetic luminosity of the outflow (\dotE_out) is well below 1% of the kinetic power of the jet (P_jet). Thus, the jet remains the major driver of the radio-loud AGN feedback at least on pc scale and beyond. The warm absorber parameters (N_H, ξ) of BLRGs span similar range of values of type 1 radio-quiet AGNs. However, when the mass outflow rate of BLRGs and Seyfert 1s is plotted as a function of the radio-loudness, R=Log [νL_ν(5GHz)/L_(2-10keV)], the mass outflow rate seems to increase with radio power.

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arXiv2011

Multiwavelength campaign on Mrk 509 VII. Relative abundances of the warm absorber

Context. The study of abundances in the nucleus of active galaxies allows us to investigate the evolution of abundance by comparing local and higher redshift galaxies. However, the methods used so far have substantial drawbacks or rather large uncertainties. Some of the measurements are at odds with the initial mass function derived from the older stellar population of local elliptical galaxies. Aims. We determine accurate and reliable abundances of C, N, Ne, and Fe relative to O from the narrow absorption lines observed in the X-ray spectra of Mrk 509. Methods. We use the stacked 600 ks XMM-Newton RGS and 180 ks Chandra LETGS spectra. Thanks to simultaneous observations with INTEGRAL and the optical monitor on-board XMM-Newton for the RGS observations and HST-COS and Swift for the LETGS observations, we have an individual spectral energy distribution for each dataset. Owing to the excellent quality of the RGS spectrum, the ionisation structure of the absorbing gas is well constrained, allowing for a reliable abundance determination using ions over the whole observed range of ionisation parameters. Results. We find that the relative abundances are consistent with the proto-solar abundance ratios: C/O = 1.19$\pm$0.08, N/O = 0.98$\pm$0.08, Ne/O = 1.11$\pm$0.10, Mg/O = 0.68$\pm$0.16, Si/O = 1.3$\pm$0.6, Ca/O = 0.89$\pm$0.25, and Fe/O = 0.85$\pm$0.06, with the exception of S, which is slightly under-abundant, S/O = 0.57$\pm$0.14. Our results, and their implications, are discussed and compared to the results obtained using other techniques to derive abundances in galaxies.

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arXiv2011

Multiwavelength campaign on Mrk 509. I. Variability and spectral energy distribution

(Abridged) Active galactic nuclei show a wealth of interesting physical processes, some of which are poorly understood. We want to address a number of open questions, including the location and physics of the outflow from AGN, the nature of the continuum emission, the geometry and physical state of the X-ray broad emission line region, the Fe-K line complex, the metal abundances of the nucleus and finally the interstellar medium of our own Galaxy. We study one of the best targets for these aims, the Seyfert 1 galaxy Mrk 509 with a multiwavelength campaign using five satellites (XMM-Newton, INTEGRAL, Chandra, HST and Swift) and two ground-based facilities (WHT and PAIRITEL). Our observations cover more than five decades in frequency, from 2 um to 200 keV. The combination of high-resolution spectroscopy and time variability allows us to disentangle and study the different components. Our campaign covers 100 days from September to December 2009, and is centred on a simultaneous set of deep XMM-Newton and INTEGRAL observations with regular time intervals, spanning seven weeks. We obtain a continuous light curve in the X-ray and UV band, showing a strong, up to 60% flux increase in the soft X-ray band during the three weeks in the middle of our deepest monitoring campaign, and which is correlated with an enhancement of the UV flux. This allows us to study the time evolution of the continuum and the outflow. By stacking the observations, we have also obtained one of the best X-ray and UV spectra of a Seyfert galaxy ever obtained. In this paper we also study the effects of the spectral energy distribution (SED) that we obtained on the photo-ionisation equilibrium. Thanks to our broad-band coverage, uncertainties on the SED do not strongly affect the determination of this equilibrium.

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arXiv2011

Multiwavelength campaign on Mrk 509. II. Analysis of high-quality Reflection Grating Spectrometer spectra

We study the bright Seyfert 1 galaxy Mrk~509 with the Reflection Grating Spectrometers (RGS) of XMM-Newton using the RGS multi-pointing mode of XMM-Newton for the first time in order to constrain the properties of the outflow in this object. We want to obtain the most accurate spectral properties from the 600 ks spectrum of Mrk 509 which has excellent statistical quality. We derive an accurate relative calibration for the effective area of the RGS, derive an accurate absolute wavelength calibration, improve the method for adding time-dependent spectra and enhance the efficiency of the spectral fitting by two orders of magnitude. We show the major improvement of the spectral data quality due to the use of the new RGS multi-pointing mode of XMM-Newton. We illustrate the gain in accuracy by showing that with the improved wavelength calibration the two velocity troughs observed in UV spectra are resolved.

astro-ph.CO↗

arXiv2011

Multiwavelength campaign on Mrk 509. III. The 600 ks RGS spectrum: unravelling the inner region of an AGN

We present the results of our 600 ks RGS observation as part of the multiwavelength campaign on Mrk 509. The very high quality of the spectrum allows us to investigate the ionized outflow with an unprecedented accuracy due to the long exposure and the use of the RGS multipointing mode. We detect multiple absorption lines from the interstellar medium and from the ionized absorber in Mrk 509. A number of emission components are also detected, including broad emission lines consistent with an origin in the broad line region, the narrow OVII forbidden emission line and also (narrow) radiative recombination continua. The ionized absorber consists of two velocity components (v = -13 \pm 11 km/s and v = -319 \pm 14 km/s), which both are consistent with earlier results, including UV data. There is another tentative component outflowing at high velocity, -770 \pm 109 km/s, which is only seen in a few highly ionized absorption lines. The outflow shows discrete ionization components, spanning four orders of magnitude in ionization parameter. Due to the excellent statistics of our spectrum, we demonstrate for the first time that the outflow in Mrk 509 in the important range of log xi between 1-3 cannot be described by a smooth, continuous absorption measure distribution, but instead shows two strong, discrete peaks. At the highest and lowest ionization parameters we cannot differentiate smooth and discrete components.

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