68 research outputs found
Relation between winds and jets in radio-loud AGN
We investigate the relation between the two modes of outflow (wind and jet)
in radio-loud active galactic nuclei (AGN). For this study we have carried out
a systematic and homogeneous analysis of XMM-Newton spectra of a sample of 16
suitable radio-loud Seyfert-1 AGN. The ionised winds in these AGN are
parameterised through high-resolution X-ray spectroscopy and photoionisation
modelling. We discover a significant inverse correlation between the column
density NH of the ionised wind and the radio-loudness parameter R of the jet.
We explore different possible explanations for this NH-R relation and find that
ionisation, inclination, and luminosity effects are unlikely to be responsible
for the observed relation. We argue that the NH-R relation is rather a
manifestation of the magnetic driving mechanism of the wind from the accretion
disk. Change in the magnetic field configuration from toroidal to poloidal,
powering either the wind or the jet mode of the outflow, is the most feasible
explanation for the observed decline in the wind NH as the radio jet becomes
stronger. Our findings provide evidence for a wind-jet bimodality in radio-loud
AGN and shine new light on the link between these two modes of outflow. This
has far-reaching consequences for the accretion disk structure and the wind
ejection mechanism.Comment: Accepted for publication in Astronomy & Astrophysics (A&A), 10 pages,
4 figure
Modelling the disk atmosphere of the low mass X-ray binary EXO 0748-676
Low mass X-ray binaries exhibit ionized emission from an extended disk
atmosphere that surrounds the accretion disk. However, its nature and geometry
is still unclear. In this work we present a spectral analysis of the extended
atmosphere of EXO 0748-676 using high-resolution spectra from archival
XMM-Newton observations. We model the RGS spectrum that is obtained during the
eclipses. This enables us to model the emission lines that come only from the
extended atmosphere of the source, and study its physical structure and
properties. The RGS spectrum reveals a series of emission lines consistent with
transitions of O VIII, O VII, Ne IX and N VII. We perform both Gaussian line
fitting and photoionization modelling. Our results suggest that there are two
photoionization gas components, out of pressure equilibrium with respect to
each other. One with ionization parameter of 2.5 and a large opening angle, and
one with 1.3. The second component is possibly covering a smaller fraction of
the source. From the density diagnostics of the O vii triplet using
photoionization modelling, we detect a rather high density plasma of > 10^13
cm^-3 for the lower ionization component. This latter component also displays
an inflow velocity. We propose a scenario where the high ionization component
constitutes an extended upper atmosphere of the accretion disk. The lower
ionization component may instead be a clumpy gas created from the impact of the
accretion stream with the disk.Comment: A&A accepted, 10 pages, 9 figure
The multi-epoch X-ray tale of I Zwicky 1 outflows
The narrow-line Seyfert 1 galaxy I Zwicky 1 shows a unique and complex system
of ionised gas in outflow, which consists of an ultra-fast wind and a
two-component warm absorber. In the last two decades, XMM-Newton monitored the
source multiple times enabling the study of the long-term variability of the
various outflows. Plasma in photoionisation equilibrium with the ionising
source responds and varies accordingly to any change of the ionising
luminosity. However, detailed modelling of the past RGS data has shown no
correlation between the plasma ionisation state and the ionising continuum,
revealing a complex long-term variability of the multi-phase warm absorber.
Here, we present a new observation of I Zwicky 1 by XMM-Newton taken in early
2020 characterised by a lower X-ray flux state. The soft X-ray spectrum from
the RGS reveals the two components of the warm absorber with and . Comparing our results with the previous
observations, the ionisation state of the two absorbing gas components is
continuously changing, following the same unpredictable behaviour. The new
results strengthen the scenario in which the ionisation state of the warm
absorber is driven by the density of the gas rather than the ionising
luminosity. In particular, the presence of a radiation driven, inhomogeneous
clumpy outflow may explain both the variability in ionisation throughout the
years and the line-locked N V system observed in the UV band. Finally, the
EPIC-pn spectrum reveals an ultra-fast wind with an outflow velocity of and ionisation parameter of .Comment: 16 pages, 11 figures, 3 tables, accepted for publication in MNRA
Time-dependent photoionization spectroscopy of the Seyfert galaxy NGC 3783
We present an investigation into the spectroscopic properties of
non-equilibrium photoionization processes operating in a time-evolving mode.
Through a quantitative comparison between equilibrium and time-evolving models,
we find that the time-evolving model exhibits a broader distribution of charge
states compared to the equilibrium model, accompanied by a slight shift in the
peak ionization state depending on the source variability and gas density. The
time-evolving code, tpho in SPEX, has been successfully employed to analyze the
spectral properties of warm absorbers in the Seyfert galaxy NGC 3783. The
incorporation of variability in the tpho model improves the fits of the
time-integrated spectra, providing more accurate descriptions to the average
charge states of several elements, in particular for Fe which is peaked around
Fe XIX. The inferred densities and distances of the relevant X-ray absorber
components are estimated to be approximately a few 1E11 per cubic meter and
less than 1 pc, respectively. Furthermore, the updated fit suggests a potential
scenario in which the observed absorbers are being expelled from the central
AGN at the escape velocities. This implies that these absorbers might not play
a significant role in the AGN feedback mechanism.Comment: accepted for publication in Astronomy and Astrophysic
First High-resolution Spectroscopy of X-Ray Absorption Lines in the Obscured State of NGC 5548
Multiwavelength spectroscopy of NGC 5548 revealed remarkable changes due to the presence of an obscuring wind from the accretion disk. This broadened our understanding of obscuration and outflows in active galactic nuclei. Swift monitoring of NGC 5548 shows that over the last 10 yr, the obscuration has gradually declined. This provides a valuable opportunity for analyses that have not been feasible before because of too much obscuration. The lowered obscuration, together with the high-energy spectral coverage of Chandra HETG, facilitates the first study of X-ray absorption lines in the obscured state. The comparison of the lines (Mg xi, Mg xii, Si xiii, and Si xiv) between the new and historical spectra reveals interesting changes, most notably the He-like absorption being significantly diminished in 2022. Our study finds that the changes are caused by an increase in both the ionization parameter and the column density of the warm-absorber outflow in the obscured state. This is contrary to the shielding scenario that is evident in the appearance of the UV lines, where the inner obscuring wind shields outflows that are farther out, thus lowering their ionization. The X-ray absorption lines in the HETG spectra appear to be unaffected by the obscuration. The results suggest that the shielding is complex because various components of the ionized outflow are affected differently. We explore various possibilities for the variability behavior of the X-ray absorption lines and find that the orbital motion of a clumpy ionized outflow traversing our line of sight is the most likely explanation
Charge exchange in the ultraviolet : implication for interacting clouds in the core of NGC 1275
Charge exchange emission is known to provide a key diagnostic to the interface between hot and cold matter in many astrophysical environments. Most of the recent charge exchange studies focus on its emission in the X-ray band, but few on the UV part, although the latter can also provide a powerful probe of the charge exchange process. An atomic calculation, as well as an application to observed data, are presented to explore and describe the potential use of the UV data for the study of cosmic charge exchange. Using the newest charge exchange model in the SPEX code v3.03, we re-analyze an archival Hubble STIS data of the central region of NGC 1275. The NGC 1275 spectrum shows hints for three possible weak lines at about 1223.6~{\AA}, 1242.4~{\AA}, and 1244.0~{\AA}, each with a significance of about . The putative features are best explained by charge exchange between highly ionized hydrogen, neon, and sulfur with neutral matter. The wavelengths of the charge exchange lines are found robustly with uncertainties ~{\AA}. The possible charge exchange emission shows a line-of-sight velocity offset of about km s with respect to the NGC 1275 nucleus, which resembles one of the Ly absorbers reported in Baum et al. (2005). This indicates that the charge exchange lines might be emitted as the same position of the absorber, which could be ascribed to outflowing gas from the nucleus
Accretion and outflow of gas in Markarian 509
A major uncertainty in models for photoionised outflows in AGN is the
distance of the gas to the central black hole. We present 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.
Mrk 509 was monitored by XMM-Newton, Integral, Chandra, HST/COS and Swift in
2009. We have studied the response of the photoionised gas to the changes in
the ionising flux produced by the central regions. We were able to put tight
constraints on the variability of the absorbers from day to year time scales.
This allowed us to develop a model for the time-dependent photoionisation in
this source.
We find that the more highly ionised gas producing most X-ray line opacity is
at least 5 pc away from the core; upper limits to the distance of various
absorbing components range between 20 pc up to a few kpc. The more lowly
ionised gas producing most UV line opacity is at least 100 pc away from the
nucleus.
These results point to an origin of the dominant, slow (v<1000 km/s) outflow
components in the NLR or torus-region of Mrk 509. We find that while the
kinetic luminosity of the outflow is small, the mass carried away is likely
larger than the 0.5 Solar mass per year accreting onto the black hole.
We also determined the chemical composition of the outflow as well as
valuable constraints on the different emission regions. We find for instance
that the resolved component of the Fe-K line originates from a region 40-1000
gravitational radii from the black hole, and that the soft excess is produced
by Comptonisation in a warm (0.2-1 keV), optically thick (tau~10-20) corona
near the inner part of the disk.Comment: 4 pages, 1 figure, Proceedings of IAUS 290 "Feeding Compact Objects:
Accretion on All Scales", C. M. Zhang, T. Belloni, M. Mendez & S. N. Zhang
(eds.
Simultaneous Millimeter-wave and X-ray monitoring of the Seyfert Galaxy NGC 7469
We report on daily monitoring of the Seyfert galaxy NGC 7469, around 95 GHz
and 143 GHz, with the IRAM 30 m radio telescope, and with the Swift X-Ray and
UV/Optical telescopes, over an overlapping period of 45 days. The source was
observed on 36 days with IRAM, and the flux density in both mm bands was on
average mJy, but varied by , and by up to a factor of 2
between days. The present IRAM variability parameters are consistent with
earlier CARMA monitoring, which had only 18 data points. The X-ray light curve
of NGC 7469 over the same period spans a factor of 5 in flux with small
uncertainties. Similar variability in the mm-band and in the X-rays lends
support to the notion of both sources originating in the same physical
component of the AGN, likely the accretion disk corona. Simultaneous monitoring
in eight UV/optical bands shows much less variability than the mm and X-rays,
implying this light originates from a different AGN component, likely the
accretion disk itself. We use a tentative 14 day lag of the X-ray light curve
with respect to the 95 GHz light curve to speculate on coronal implications.
More precise mm-band measurements of a sample of X-ray-variable AGN are needed,
preferably also on time scales of less than a day where X-rays vary
dramatically, in order to properly test the physical connection between the two
bands
Accretion and outflow of gas in Markarian 509
A major uncertainty in models for photoionised outflows in AGN is the distance of the gas to the central black hole. We present 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. Mrk 509 was monitored by XMM-Newton, Integral, Chandra, HST/COS and Swift in 2009. We have studied the response of the photoionised gas to the changes in the ionising flux produced by the central regions. We were able to put tight constraints on the variability of the absorbers from day to year time scales. This allowed us to develop a model for the time-dependent photoionisation in this source. We find that the more highly ionised gas producing most X-ray line opacity is at least 5 pc away from the core; upper limits to the distance of various absorbing components range between 20 pc up to a few kpc. The more lowly ionised gas producing most UV line opacity is at least 100 pc away from the nucleus. These results point to an origin of the dominant, slow (v<1000 km s−1) outflow components in the NLR or torus-region of Mrk 509. We find that while the kinetic luminosity of the outflow is small, the mass carried away is likely larger than the 0.5 Solar mass per year accreting onto the black hole. We also determined the chemical composition of the outflow as well as valuable constraints on the different emission regions. We find for instance that the resolved component of the Fe-K line originates from a region 40-1000 gravitational radii from the black hole, and that the soft excess is produced by Comptonisation in a warm (0.2-1 keV), optically thick (τ~ 10-20) corona near the inner part of the dis
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