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Browsing by Author "Bianchi, S."

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    A fast and long-lived outflow from the supermassive black hole in NGC 5548
    Kaastra, J. S.; Kriss, G. A.; Cappi, M.; Mehdipour, M.; Petrucci, P. O.; Steenbrugge, K. C.; Arav, Nahum; Behar, E.; Bianchi, S.; Boissay, R.; Branduardi-Raymont, G.; Chamberlain, C.; Costantini, E.; Ely, J. C.; Ebrero, J.; Di Gesu, L.; Harrison, F. A.; Kaspi, S.; Malzac, J.; De Marco, B.; Matt, G.; Nandra, K.; Paltani, S.; Person, R.; Peterson, B. M.; Pinto, C.; Ponti, G.; Nunez, F. P.; De Rosa, A.; Seta, H.; Ursini, F.; de Vries, C. P.; Walton, D. J.; Whewell, M. (Amer Assoc Advancement Science, 2014-07-04)
    Supermassive black holes in the nuclei of active galaxies expel large amounts of matter through powerful winds of ionized gas. The archetypal active galaxy NGC 5548 has been studied for decades, and high-resolution X-ray and UV observations have previously shown a persistent ionized outflow. An observing campaign in 2013 with six space observatories shows the nucleus to be obscured by a long-lasting, clumpy stream of ionized gas never seen before. It blocks 90% of the soft X-ray emission and causes simultaneous deep, broad UV absorption troughs. The outflow velocities of this gas are up to five times faster than those in the persistent outflow, and at a distance of only a few light days from the nucleus, it may likely originate from the accretion disk.
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    Multiwavelength campaign on Mrk 509 I. Variability and spectral energy distribution
    Kaastra, J. S.; Petrucci, P. O.; Cappi, M.; Arav, Nahum; Behar, E.; Bianchi, S.; Bloom, J.; Blustin, A. J.; Branduardi-Raymont, G.; Costantini, E.; Dadina, M.; Detmers, R. G.; Ebrero, J.; Jonker, P. G.; Klein, C.; Kriss, G. A.; Lubinski, P.; Malzac, J.; Mehdipour, M.; Paltani, S.; Pinto, C.; Ponti, G.; Ratti, E. M.; Smith, R. A. N.; Steenbrugge, K. C.; de Vries, C. P. (EDP Sciences, 2011-10)
    Context. Active galactic nuclei (AGN) show a wealth of interesting physical processes, some of which are poorly understood. In a broader context, they play an important role in processes that are far beyond their immediate surroundings, owing to the high emitted power. Aims. 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 as seen through the signatures it imprints on the X-ray and UV spectra of AGN. Methods. 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 μm 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. Results. 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. Conclusions. Here we present our very successful campaign and in a series of subsequent papers we will elaborate on different aspects of our study.
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    Multiwavelength campaign on Mrk 509 III. The 600 ks RGS spectrum: unravelling the inner region of an AGN
    Detmers, R. G.; Kaastra, J. S.; Steenbrugge, K. C.; Ebrero, J.; Kriss, G. A.; Arav, Nahum; Behar, E.; Costantini, E.; Branduardi-Raymont, G.; Mehdipour, M.; Bianchi, S.; Cappi, M.; Petrucci, P. O.; Ponti, G.; Pinto, C.; Ratti, E. M.; Holczer, T. (EDP Sciences, 2011-10)
    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 O VII forbidden emission line and also (narrow) radiative recombination continua. The ionized absorber consists of two velocity components (upsilon = -13 +/- 11 km s(-1) and upsilon = -319 +/- 14 km s(-1)), which both are consistent with earlier results, including UV data. There is another tentative component outflowing at high velocity, -770 +/- 109 km s(-1), 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. 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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    Multiwavelength campaign on Mrk 509 V. Chandra-LETGS observation of the ionized absorber
    Ebrero, J.; Kriss, G. A.; Kaastra, J. S.; Detmers, R. G.; Steenbrugge, K. C.; Costantini, E.; Arav, Nahum; Bianchi, S.; Cappi, M.; Branduardi-Raymont, G.; Mehdipour, M.; Petrucci, P. O.; Pinto, C.; Ponti, G. (EDP Sciences, 2011-10)
    Context. We present here the results of a 180 ks Chandra-LETGS observation as part of a large multi-wavelength campaign on Mrk 509. Aims. We study the warm absorber in Mrk 509 and use the data from a simultaneous HST-COS observation in order to assess whether the gas responsible for the UV and X-ray absorption are the same. Methods. We analyzed the LETGS X-ray spectrum of Mrk 509 using the SPEX fitting package. Results. We detect several absorption features originating in the ionized absorber of the source, along with resolved emission lines and radiative recombination continua. The absorption features belong to ions with, at least, three distinct ionization degrees. The lowest ionized component is slightly redshifted (Δv = 73 km s-1) and is not in pressure equilibrium with the others, and therefore it is not likely part of the outflow, possibly belonging to the interstellar medium of the host galaxy. The other components are outflowing at velocities of −196 and −455 km s-1, respectively. The source was observed simultaneously with HST-COS, finding 13 UV kinematic components. At least three of them can be kinematically associated with the observed X-ray components. Based on the HST-COS results and a previous FUSE observation, we find evidence that the UV absorbing gas might be co-located with the X-ray absorbing gas and belong to the same structure.
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    Multiwavelength campaign on Mrk 509 VI. HST/COS observations of the far-ultraviolet spectrum
    Kriss, G. A.; Arav, Nahum; Kaastra, J. S.; Ebrero, J.; Pinto, C.; Borguet, B.; Edmonds, Douglas; Costantini, E.; Steenbrugge, K. C.; Detmers, R. G.; Behar, E.; Bianchi, S.; Blustin, A. J.; Branduardi-Raymont, G.; Cappi, M.; Mehdipour, M.; Petrucci, P. O.; Ponti, G. (EDP Sciences, 2011-10)
    We present medium-resolution (lambda/Delta lambda similar to 20 000) ultraviolet spectra covering the 1155-1760 angstrom spectral range of the Seyfert 1 galaxy Mrk 509 obtained using the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST). Our observations were obtained simultaneously with a Low Energy Transmission Grating Spectrometer observation using the Chandra X-ray Observatory, and they are part of a multiwavelength campaign in September through December 2009 which also included observations with XMM-Newton, Swift, and INTEGRAL. Our spectra are the highest signal-to-noise observations to date of the intrinsic absorption components seen in numerous prior ultraviolet observations. To take advantage of the high S/N, we describe special calibrations for wavelength, flat-field and line-spread function corrections that we applied to the COS data. We detect additional complexity in the absorption troughs compared to prior observations made with the Space Telescope Imaging Spectrograph (STIS) on HST. We attribute the UV absorption to a variety of sources in Mrk 509, including an outflow from the active nucleus, the interstellar medium and halo of the host galaxy, and possible infalling clouds or stripped gaseous material from a merger that are illuminated by the ionizing radiation of the active nucleus. Variability between the STIS and COS observation of the most blue-shifted component (#1) allows us to set an upper limit on its distance of <250 pc. Similarly, variability of component 6 between FUSE observations limits its distance to <1.5 kpc. The absorption lines in all components only partially cover the emission from the active nucleus with covering fractions that are lower than those seen in the prior STIS observations and are comparable to those seen in spectra from the Far Ultraviolet Spectroscopic Explorer (FUSE). Given the larger apertures of COS and FUSE compared to STIS, we favor scattered light from an extended region near the active nucleus 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. We conclude that the outflow from the active nucleus is a multiphase wind.
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    Multiwavelength campaign on Mrk 509 VII. Relative abundances of the warm absorber
    Steenbrugge, K. C.; Kaastra, J. S.; Detmers, R. G.; Ebrero, J.; Ponti, G.; Costantini, E.; Kriss, G. A.; Mehdipour, M.; Pinto, C.; Branduardi-Raymont, G.; Behar, E.; Arav, Nahum; Cappi, M.; Bianchi, S.; Petrucci, P. O.; Ratti, E. M.; Holczer, T. (EDP Sciences, 2011-10)
    Context. The study of abundances in the nucleus of active galaxies allows us to investigate the evolution of the 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  ±  0.08, N/O = 0.98  ±  0.08, Ne/O = 1.11  ±  0.10, Mg/O = 0.68  ±  0.16, Si/O = 1.3  ±  0.6, Ca/O = 0.89  ±  0.25, and Fe/O = 0.85  ±  0.06, with the exception of S, which is slightly under-abundant, S/O = 0.57  ±  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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    Multiwavelength campaign on Mrk 509 VIII. Location of the X-ray absorber
    Kaastra, J. S.; Detmers, R. G.; Mehdipour, M.; Arav, Nahum; Behar, E.; Bianchi, S.; Branduardi-Raymont, G.; Cappi, M.; Costantini, E.; Ebrero, J.; Kriss, G. A.; Paltani, S.; Petrucci, P. O.; Pinto, C.; Ponti, G.; Steenbrugge, K. C.; de Vries, C. P. (EDP Sciences, 2012-03)
    Aims. More than half of all active galactic nuclei show strong photoionised outflows. A major uncertainty in models for these outflows is the distance of the gas to the central black hole. We use the results of a massive multiwavelength monitoring campaign on the bright Seyfert 1 galaxy Mrk 509 to constrain the location of the outflow components dominating the soft X-ray band. Methods. Mrk 509 was monitored by XMM-Newton and other satellites in 2009. We have studied the response of the photoionised gas to the changes in the ionising flux produced by the central regions. We used the five discrete ionisation components A–E that we detected in the time-averaged spectrum taken with the RGS instrument. By using the ratio of fluxed EPIC-pn and RGS spectra, we were able to put tight constraints on the variability of the absorbers. Monitoring with the Swift satellite started six weeks before the XMM-Newton observations. This allowed us to use the history of the ionising flux and to develop a model for the time-dependent photoionisation in this source. Results. Components A and B are too weak for variability studies, but the distance for component A is already known from optical imaging of the [O iii] line to be about 3 kpc. During the five weeks of the XMM-Newton observations we found no evidence of changes in the three X-ray dominant ionisation components C, D, and 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 that the density is very low, and we derive firm lower limits to the distance of these components. For component D we find evidence for variability on longer time scales by comparing our spectra to archival data taken in 2000 and 2001, 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 is between 5–33 pc, and component E has a distance  >5 pc but smaller than 21–400 pc, depending upon modelling details. These results are consistent with the upper limits that we derived from the HST/COS observations of our campaign and point to an origin of the dominant, slow (v < 1000 km s-1) outflow components in the NLR or torus-region of Mrk 509.
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    Multiwavelength campaign on Mrk 509 X. Lower limit on the distance of the absorber from HST COS and STIS spectroscopy
    Arav, Nahum; Borguet, Benoit C. J.; Kriss, G. A.; Kaastra, J. S.; Behar, E.; Cappi, M.; Costantini, E.; Detmers, R. G.; Ebrero, J.; Mehdipour, M.; Paltani, S.; Petrucci, P. O.; Pinto, C.; Ponti, G.; Steenbrugge, K. C.; de Vries, C. P.; Bianchi, S. (EDP Sciences, 2012-08)
    Aims. Active galactic nuclei (AGN) often show evidence of photoionized outflows. A major uncertainty in models for these outflows is the distance (R) to the gas from the central black hole. In this paper we use the HST/COS data from a massive multi-wavelength monitoring campaign on the bright Seyfert I galaxy Mrk 509, in combination with archival HST/STIS data, to constrain the location of the various kinematic components of the outflow. Methods. We compare the expected response of the photoionized gas to changes in ionizing flux with the changes measured in the data using the following steps: 1) We compare the column densities of each kinematic component measured in the 2001 STIS data with those measured in the 2009 COS data; 2) We use time-dependent photionization calculations with a set of simulated lightcurves to put statistical upper limits on the hydrogen number density (nH) that are consistent with the observed small changes in the ionic column densities; 3) From the upper limit on nH, we calculate a lower limit on the distance to the absorber from the central source via the prior determination of the ionization parameter. Our method offers two improvements on traditional timescale analysis. First, we account for the physical behavior of AGN lightcurves. Second, our analysis accounts for the quality of measurement in cases where no changes are observed in the absorption troughs. Results. The very small variations in trough ionic column densities (mostly consistent with no change) between the 2001 and 2009 epochs allow us to put statistical lower limits on R between 100–200 pc for all the major UV absorption components at a confidence level of 99%. These results are mainly consistent with the independent distance estimates derived for the warm absorbers from the simultaneous X-ray spectra. Based on the 100–200 pc lower limit for all the UV components, this absorber cannot be connected with an accretion disc wind. The outflow might have originated from the disc, but based on simple ballistic kinematics, such an event had to occur at least 300 000 years ago in the rest frame of the source.
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    Multiwavelength campaign on Mrk 509 XI. Reverberation of the Fe K alpha line
    Ponti, G.; Cappi, M.; Costantini, E.; Bianchi, S.; Kaastra, J. S.; De Marco, B.; Fender, R. P.; Petrucci, P. O.; Kriss, G. A.; Steenbrugge, K. C.; Arav, Nahum; Behar, E.; Branduardi-Raymont, G.; Dadina, M.; Ebrero, J.; Lubinski, P.; Mehdipour, M.; Paltani, S.; Pinto, C.; Tombesi, F. (EDP Sciences, 2013-01)
    Context. 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 4 days, and includes a reanalysis of previous XMM-Newton and Chandra observations. Aims. We aim at understanding the origin and location of the Fe K emission and absorption regions. Results. Mrk 509 shows a clear (EW = 58 ± 4 eV) neutral Fe Kα emission line that can be decomposed into a narrow (σ = 0.027 keV) component (found in the Chandra HETG data) plus a resolved (σ = 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 Kα reverberates the hard X-ray continuum without any measurable lag, suggesting that the region producing the resolved Fe Kα component is located within a few light days to a week (r ≲ 103rg) 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 Kα could thus be emitted from the inner regions of the BLR, i.e. within the  ~80 light days indicated by the Hβ line measurements. In addition to these two neutral Fe Kα components, we confirm the detection of weak (EW ~ 8–20 eV) ionised Fe K emission. This ionised line can be modelled with either a blend of two narrow Fe xxv and Fe xxvi emission lines (possibly produced by scattering from distant material) or with a single relativistic line produced, in an ionised disc, down to a few rg from the BH. In the latter interpretation, the presence of an ionised standard α-disc, down to a few rg, is consistent with the source high Eddington ratio. Finally, we observe a weakening/disappearing of the medium- and high-velocity high-ionisation Fe K wind features found in previous XMM-Newton observations. Conclusions. This campaign has made the first reverberation measurement of the resolved component of the Fe Kα line possible, 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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    Multiwavelength campaign on Mrk 509: XVI. Continued HST/COS monitoring of the far-ultraviolet spectrum
    Kriss, G. A.; Arav, Nahum; Edmonds, Douglas; Ely, J. C.; Kaastra, J. S.; Bianchi, S.; Cappi, M.; Costantini, E.; Ebrero, J.; Mehdipour, M.; Paltani, S.; Petrucci, P. O.; Ponti, G. (EDP Sciences, 2019-03-07)
    Aims. To elucidate the location, physical conditions, mass outflow rate, and kinetic luminosity of the outflow from the active nucleus of the Seyfert 1 galaxy Mrk 509, we used coordinated UV and X-ray spectral observations in 2012 to follow up our lengthier campaign conducted in 2009. Methods. We observed Mrk 509 with the Cosmic Origins Spectrograph (COS) on the Hubble Space Telescope (HST) on 2012-09-03 and 2012-10-11 coordinated with X-ray observations using the High Energy Transmission Grating on the Chandra X-ray Observatory. Our far-ultraviolet spectra used grating G140L on COS to cover wavelengths from 920-2000 Å at a resolving power of ∼2000, and gratings G130M and G160M to cover 1160-1750 Å at a resolving power of ∼15, 000. Results. We detect variability in the blueshifted UV absorption lines on timescales spanning 3-12 years. The inferred densities in the absorbing gas are greater than log n cm -3 ∼ 3. For ionization parameters ranging over log U =-1.5 to-0.2, we constrain the distances of the absorbers to be closer than 220 pc to the active nucleus. Conclusions. The impact on the host galaxy appears to be confined to the nuclear region. © 2019 G. A. Kriss et al.