41 research outputs found
On the presence of ultra-fast outflows in the WAX sample of Seyfert galaxies
The study of winds in active galactic nuclei (AGN) is of utmost importance as
they may provide the long sought-after link between the central black hole and
the host galaxy, establishing the AGN feedback. Recently, Laha et al. (2014)
reported the X-ray analysis of a sample of 26 Seyferts observed with
XMM-Newton, which are part of the so-called warm absorbers in X-rays (WAX)
sample. They claim the non-detection of Fe K absorbers indicative of ultra-fast
outflows (UFOs) in four observations previously analyzed by Tombesi et al.
(2010). They mainly impute the Tombesi et al. detections to an improper
modeling of the underlying continuum in the E=4-10 keV band. We therefore
re-address here the robustness of these detections and we find that the main
reason for the claimed non-detections is likely due to their use of single
events only spectra, which reduces the total counts by 40%. Performing a
re-analysis of the data in the whole E=0.3-10 keV energy band using their
models and spectra including also double events, we find that the blue-shifted
Fe K absorption lines are indeed detected at >99%. This work demonstrates the
robustness of these detections in XMM-Newton even including complex model
components such as reflection, relativistic lines and warm absorbers.Comment: 5 pages, 1 figure, accepted for publication in MNRA
Variable X-ray absorption in the mini-BAL QSO PG 1126-041
X-ray studies of active galactic nuclei (AGN) with powerful nuclear winds are
important for constraining the physics of the inner accretion/ejection flow
around supermassive black holes (SMBHs) and for understanding the impact of
such winds on the AGN environment. Our main scientific goal is to constrain the
properties of the circum-nuclear matter close to the SMBH in the mini-broad
absorption line quasar (mini-BAL QSO) PG 1126-041 using a multi-epoch
observational campaign with XMM-Newton. We performed temporally resolved X-ray
spectroscopy and simultaneous UV and X-ray photometry on the most complete set
of observations and on the deepest X-ray exposure of a mini-BAL QSO ever. We
found complex X-ray spectral variability on time scales of both months and
hours, which is best reproduced by means of variable massive ionized absorbers
along the line of sight. As a consequence, the observed optical-to-X-ray
spectral index is found to be variable with time. In the highest
signal-to-noise observation we detected highly ionized X-ray absorbing material
outflowing much faster (v ~ 16500 km/s) than the UV absorbing one (v ~ 5000
km/s). This highly ionized absorber is found to be variable on very short (a
few kiloseconds) time scales. Our findings are qualitatively consistent with
line-driven accretion disk winds scenarios. Our observations have opened the
time-resolved X-ray spectral analysis field for mini-BAL QSOs. Only with future
deep studies will we be able to map the dynamics of the inner flow and
understand the physics of AGN winds and their impact on the environment.Comment: Replaced to match the published versio
The Suzaku View of Highly Ionized Outflows in AGN
We present the results of a new spectroscopic study of Fe K-band absorption in active galactic nuclei (AGN). Using data obtained from the Suzaku public archive we have performed a statistically driven blind search for Fe XXV Healpha and/or Fe XXVI Lyalpha absorption lines in a large sample of 51 Type 1.01.9 AGN. Through extensive Monte Carlo simulations we find that statistically significant absorption is detected at E greater than or approximately equal to 6.7 keV in 20/51 sources at the P(sub MC) greater than or equal tov 95 per cent level, which corresponds to approximately 40 per cent of the total sample. In all cases, individual absorption lines are detected independently and simultaneously amongst the two (or three) available X-ray imaging spectrometer detectors, which confirms the robustness of the line detections. The most frequently observed outflow phenomenology consists of two discrete absorption troughs corresponding to Fe XXV Healpha and Fe XXVI Lyalpha at a common velocity shift. From xstar fitting the mean column density and ionization parameter for the Fe K absorption components are log (N(sub H) per square centimeter)) is approximately equal to 23 and log (Xi/erg centimeter per second) is approximately equal to 4.5, respectively. Measured outflow velocities span a continuous range from less than1500 kilometers per second up to approximately100 000 kilometers per second, with mean and median values of approximately 0.1 c and approximately 0.056 c, respectively. The results of this work are consistent with those recently obtained using XMM-Newton and independently provides strong evidence for the existence of very highly ionized circumnuclear material in a significant fraction of both radio-quiet and radio-loud AGN in the local universe
Apoferritin nanocage as streptomycin drug reservoir: Technological optimization of a new drug delivery system
The aim of this study is to formulate and characterize streptomycin-loaded apoferritin nanoparticles (ApoStrep NPs) for their potential therapeutic use in bacterial resistant infections (i.e. tuberculosis). ApoStrep NPs were prepared by disassembly/reassembly process via pH method and changing apoferritin/drug molar ratio, purified by dialyses process also associated with gel filtration chromatography and characterized in their chemico-physical and technological parameters as yield, size distribution, polidispersivity, morphology, internal structure, zeta potential and loading efficacy. The results showed that spherical reproducible NPs could be obtained by using apoferritin/drug molar ratio lower than 1:25 and purification based on the combination of dialysis and gel filtration chromatography. Photon correlation spectroscopy, Uv–visible detection and electron microscopy showed the maintenance of the native apoferritin chemico-physical properties and structure. When formulated with apoferritin/drug 1:10 and 1:25 molar ratio, ApoStrep NPs showed remarkable encapsulation efficacy (35% and 28%, respectively) along with kinetic profile of drug delivery, approximately 15% at 37 °C in 72 h, as evidenced by “in vitro” release experiments
Is global cardiovascular risk considered in current practice? Treatment and control of hypertension, hyperlipidemia, and diabetes according to patients’ risk level
Daria Roccatagliata1, Fausto Avanzini1, Lara Monesi1, Vittorio Caimi2, Davide Lauri1, Paolo Longoni3, Roberto Marchioli4, Massimo Tombesi2, Gianni Tognoni1, Maria Carla Roncaglioni1, on behalf of the Collaborative Group Risk and Prevention Study*1Istituto di Ricerche Farmacologiche “Mario Negri”, Milano, Italy; 2CSeRMEG Centro Studi e Ricerca in Medicina Generale, Monza, Italy; 3CoS Consorzio Sanità, Milano, Italy; 4Consorzio Mario Negri Sud, S. Maria Imbaro, Italy *A full list of investigators is reported in the AppendixObjectives: To assess the pharmacological treatment and the control of major modifiable cardiovascular risk factors in everyday practice according to the patients’ cardiovascular risk level.Methods: In a cross-sectional study general practitioners (GPs) had to identify a random sample of their patients with cardiovascular risk factors or diseases and collect essential data on the pharmacological treatment and control of hypertension, hyperlipidemia, and diabetes according to the patients’ cardiovascular risk level and history of cardiovascular disease. Participants were subjects of both sexes, aged 40–80 years, with at least one known cardiovascular risk factor or a history of cardiovascular diseases.Results: From June to December 2000, 162 Italian GPs enrolled 3120 of their patients (2470 hypertensives, 1373 hyperlipidemics, and 604 diabetics). Despite the positive association between the perceived level of global cardiovascular risk and lipid-lowering drug prescriptions in hyperlipidemic subjects (from 26% for lowest risk to 56% for highest risk p < 0.0001) or the prescription of combination therapy in hypertensives (from 41% to 70%, p < 0.0001) and diabetics (from 24% to 43%, p = 0.057), control was still inadequate in 48% of diabetics, 77% of hypertensives, and 85% of hyperlipidemics, with no increase in patients at highest risk. Trends for treatment and control were similar in patients with cardiovascular diseases.Conclusions: Even in high-risk patients, despite a tendency towards more intensive treatment, pharmacological therapy is still under used and the degree of control of blood pressure, cholesterol level and diabetes is largely unsatisfactory.Keywords: global cardiovascular risk, hypertension, hyperlipideamia, diabetes, general practice
Feeding and feedback in radio galaxies and mergers: an X-ray perspective
Observations performed in the last decades have shown that supermassive black holes (SMBHs) and cosmic structures are not separate elements of the Universe. While galaxies have sizes roughly ten orders of magnitude larger than SMBHs, black holes would not exist without matter feeding them, and cosmic structures would not be the same without feedback from SMBHs. Powerful winds/jets in active galactic nuclei (AGN) may be the basis of this co-evolution. X-ray observations trace both the cold/feeding and hot/ionized feedback phases. We show the Chandra HETG spectral analysis of two radio galaxies, 3C 390.3 and 3C 120. Complex emission/absorption features are present in the soft X-rays and Fe K band. We detect a hot gas with temperature kT 0.5-1keV from broad ionized Fe L-shell lines which may originate from a kpc scale shocked bubble inflated by the wind/jet. This is reminiscent of supernova bubbles. The shape and strength of the neutral Fe K line suggest that the material feeding the accretion disk, or torus, may be in the form of Compton-thick, clumpy clouds. Such systems may likely be late stage mergers and they allow us to extend the parameter space traced by winds in Seyferts and ULIRGs
The physics and astrophysics of X-ray outflows from Active Galactic Nuclei
The highly energetic outflows from Active Galactic Nuclei detected in X-rays
are one of the most powerful mechanisms by which the central supermassive black
hole (SMBH) interacts with the host galaxy. The last two decades of high
resolution X-ray spectroscopy with XMM and Chandra have improved our
understanding of the nature of these outflowing ionized absorbers and we are
now poised to take the next giant leap with higher spectral resolution and
higher throughput observatories to understand the physics and impact of these
outflows on the host galaxy gas. The future studies on X-ray outflows not only
have the potential to unravel some of the currently outstanding puzzles in
astronomy, such as the physical basis behind the MBH relation, the
cooling flow problem in intra-cluster medium (ICM), and the evolution of the
quasar luminosity function across cosmic timescales, but also provide rare
insights into the dynamics and nature of matter in the immediate vicinity of
the SMBH. Higher spectral resolution ( eV at keV) observations
will be required to identify individual absorption lines and study the
asymmetries and shifts in the line profiles revealing important information
about outflow structures and their impact. Higher effective area () will be required to study the outflows in distant quasars,
particularly at the quasar peak era (redshift ) when the AGN
population was the brightest. Thus, it is imperative that we develop next
generation X-ray telescopes with high spectral resolution and high throughput
for unveiling the properties and impact of highly energetic X-ray outflows. A
simultaneous high resolution UV + X-ray mission will encompass the crucial AGN
ionizing continuum, and also characterize the simultaneous detections of UV and
X-ray outflows, which map different spatial scales along the line of sight.Comment: A Science White Paper submitted to the Astro2020 Decadal Surve
First detection of X-ray polarization from the accreting neutron star 4U 1820-303
This paper reports the first detection of polarization in the X-rays for
atoll-source 4U 1820-303, obtained with the Imaging X-ray Polarimetry Explorer
(IXPE) at 99.999% confidence level (CL). Simultaneous polarimetric measurements
were also performed in the radio with the Australia Telescope Compact Array
(ATCA). The IXPE observations of 4U 1820-303 were coordinated with Swift-XRT,
NICER, and NuSTAR aiming to obtain an accurate X-ray spectral model covering a
broad energy interval. The source shows a significant polarization above 4 keV,
with a polarization degree of 2.0(0.5)% and a polarization angle of -55(7) deg
in the 4-7 keV energy range, and a polarization degree of 10(2)% and a
polarization angle of -67(7) deg in the 7-8 keV energy bin. This polarization
also shows a clear energy trend with polarization degree increasing with energy
and a hint for a position-angle change of about 90 deg at 96% CL around 4 keV.
The spectro-polarimetric fit indicates that the accretion disk is polarized
orthogonally to the hard spectral component, which is presumably produced in
the boundary/spreading layer. We do not detect linear polarization from the
radio counterpart, with a 99.97% upper limit of 50% at 7.25 GHz