X-ray variability plane revisited: Role of obscuration

2019 ◽  
Vol 15 (S356) ◽  
pp. 367-367
Author(s):  
Omaira González-Martn
Keyword(s):  
Line Of Sight ◽  
Scaling Relations ◽  
X Ray ◽  
Bolometric Luminosity ◽  
Set Constraints ◽  
Physical Mechanisms ◽  
Power Spectral ◽  
First Time

AbstractScaling relations are the most powerful astrophysical tools to set constraints to the physical mechanisms of astronomical sources and to infer properties for objects where they cannot be accessed directly. We have re-investigated one of these scaling relations using powerful type 1 Seyferts; the so-called X-ray variability plane (or mass-luminosity-timescale relation, McHardy et al.2006). This relation links the power-spectral density (PSD) break frequency with the SMBH mass and the bolometric luminosity. We used all available XMM-Newton observations to study the PSD and spectra in short segments within each observation. This allows us to report for the first time that the PSD break frequency varies for each object, showing variations in 19 out of the 22 AGN analyzed. Our analysis of the variability plane confirms the relation between the break frequency and the SMBH mass and finds that the obscuration along the line of sight (or the variations on the obscuration using its standard deviation) is also a required parameter. We constrain a new variability plane of the form: log(vBreak) = – A log (MBH) + B log (NH) – C (or log(vBreak) = – A log (MBH) + B Δ (NH) + C). The X-ray variability plane found by McHardy et al. (2006) is roughly recovered when we use unobscured segments. We speculate the PSD shape is related with the outflowing wind close to the accretion disk at least for these powerful type 1 AGN (Gonzalez-Martin et al. 2018).

scholarly journals BAT AGN Spectroscopic Survey – XIX. Type 1 versus type 2 AGN dichotomy from the point of view of ionized outflows

2019 ◽  
Vol 491 (4) ◽  
pp. 5867-5880 ◽  
Author(s):  
A F Rojas ◽  
E Sani ◽  
I Gavignaud ◽  
C Ricci ◽  
I Lamperti ◽  
...  
Keyword(s):  
High Redshift ◽  
Maximum Velocity ◽  
Point Of View ◽  
Physical Parameters ◽  
X Ray ◽  
Narrow Component ◽  
Bolometric Luminosity ◽  
First Time

ABSTRACT We present a detailed study of ionized outflows in a large sample of ∼650 hard X-ray-detected active galactic neuclei (AGNs). Using optical spectroscopy from the BAT AGN Spectroscopic Survey (BASS), we are able to reveal the faint wings of the [O iii] emission lines associated with outflows covering, for the first time, an unexplored range of low AGN bolometric luminosity at low redshift (z ∼0.05). We test if and how the incidence and velocity of ionized outflow is related to AGN physical parameters: black hole mass ($\rm \mathit{ M}_{BH}$), gas column density ($\rm \mathit{ N}_{H}$), Eddington ratio ($\rm \lambda _{Edd}$), [O iii], X-ray, and bolometric luminosities. We find a higher occurrence of ionized outflows in type 1.9 (55 per cent) and type 1 AGNs (46 per cent) with respect to type 2 AGNs (24 per cent). While outflows in type 2 AGNs are evenly balanced between blue and red velocity offsets with respect to the [O iii] narrow component, they are almost exclusively blueshifted in type 1 and type 1.9 AGNs. We observe a significant dependence between the outflow occurrence and accretion rate, which becomes relevant at high Eddington ratios [log($\rm \lambda _{Edd}$) ≳ −1.7]. We interpret such behaviour in the framework of covering factor-Eddington ratio dependence. We do not find strong trends of the outflow maximum velocity with AGN physical parameters, as an increase with bolometric luminosity can be only identified when including samples of AGNs at high luminosity and high redshift taken from literature.

AGN1 vs AGN2 dichotomy as seen from the point of view of ionized outflows

2019 ◽  
Vol 15 (S356) ◽  
pp. 96-96
Author(s):  
Eleonora Sani
Keyword(s):  
Accretion Rate ◽  
Point Of View ◽  
Emission Lines ◽  
Black Hole Mass ◽  
X Ray ◽  
Bolometric Luminosity ◽  
Wide Range ◽  
Strong Contrast

AbstractI present a detailed study of ionized outflows in a large sample of 650 hard X-ray detected AGN. Taking advantage of the legacy value of the BAT AGN Spectroscopic Survey (BASS, DR1), we are able to reveal the faintest wings of the [OIII] emission lines associated with outflows. The sample allows us to derive the incidence of outflows covering a wide range of AGN bolometric luminosity and test how the outflow parameters are related with various AGN power tracers, such as black hole mass, Eddington ratio, luminosity. I’ll show how ionized outflows are more frequently found in type 1.9 and type 1 AGN (50% and 40%) with respect to the low fraction in type 2 AGN (20%). Within such a framework, I’ll demonstrate how type 2 AGN outflows are almost evenly balanced between blue- and red-shifted winds. This, in strong contrast with type 1 and type 1.9 AGN outflows which are almost exclusively blue-shifted. Finally, I’ll prove how the outflow occurrence is driven by the accretion rate, whereas the dependence of outflow properties with respect to the other AGN power tracers happens to be quite mild.

scholarly journals EXPRESS: Pulmonary Hypertension Associated With Neurofibromatosis Type 2

2021 ◽  
pp. 204589402110295
Author(s):  
Hirohisa Taniguchi ◽  
Tomoya Takashima ◽  
Ly Tu ◽  
Raphaël Thuillet ◽  
Asuka Furukawa ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Neurofibromatosis Type ◽  
Pulmonary Vascular Remodeling ◽  
Life Threatening ◽  
History Of ◽  
Pulmonary Arterial ◽  
First Time

Although precapillary pulmonary hypertension (PH) is a rare but severe complication of patients with neurofibromatosis type 1 (NF1), its association with NF2 remains unknown. Herein, we report a case of a 44-year-old woman who was initially diagnosed with idiopathic pulmonary arterial hypertension (IPAH) and treated with PAH-specific combination therapy. However, a careful assessment for a relevant family history of the disease and genetic testing reveal that this patient had a mutation in the NF2 gene. Using immunofluorescence and Western blotting, we demonstrated a decrease in endothelial NF2 protein in lungs from IPAH patients compared to control lungs, suggesting a potential role of NF2 in PAH development. To our knowledge, this is the first time that precapillary PH has been described in a patient with NF2. The altered endothelial NF2 expression pattern in PAH lungs should stimulate work to better understand how NF2 is contributing to the pulmonary vascular remodeling associated to these severe life-threatening conditions.

scholarly journals X-ray properties of He ii λ 1640 emitting galaxies in VANDELS

2020 ◽  
Vol 496 (3) ◽  
pp. 3796-3807
Author(s):  
A Saxena ◽  
L Pentericci ◽  
D Schaerer ◽  
R Schneider ◽  
R Amorin ◽  
...  
Keyword(s):  
Formation Rate ◽  
Galactic Nuclei ◽  
X Ray ◽  
Star Forming ◽  
Set Constraints ◽  
Significant Difference ◽  
Low Metallicity ◽  
Matched Samples ◽  
X Ray Binaries

ABSTRACT We explore X-ray emission from a sample of 18 He ii λ1640 emitting star-forming galaxies at z ∼ 2.3–3.6 from the VANDELS survey in the Chandra Deep Field South, to set constraints on the role of X-ray sources in powering the He ii emission. We find that 4 He ii emitters have tentative detections with S/N ∼ 2 and have X-ray luminosities, LX = 1.5−4.9 × 1041 erg s−1. The stacked luminosity of all 18 He ii emitters is 2.6 × 1041 erg s−1, and that of a subset of 13 narrow He ii emitters (FHWM(He ii) < 1000 km s−1) is 3.1 × 1041 erg s−1. We also measure stacked LX for non-He ii emitters through bootstrapping of matched samples, and find LX = 2.5 × 1041 erg s−1, which is not significantly different from LX measured for He ii emitters. The LX per star formation rate for He ii emitters (log (LX/SFR) ∼ 40.0) and non-emitters (log (LX/SFR) ∼ 39.9) are also comparable and in line with the redshift evolution and metallicity dependence predicted by models. Due to the non-significant difference between the X-ray emission from galaxies with and without He ii, we conclude that X-ray binaries or weak or obscured active galactic nuclei are unlikely to be the dominant producers of He ii ionizing photons in VANDELS star-forming galaxies at z ∼ 3. Given the comparable physical properties of both He ii emitters and non-emitters reported previously, alternative He ii ionizing mechanisms such as localized low-metallicity stellar populations, Pop-III stars, etc. may need to be explored.

scholarly journals Duck Hepatitis A Virus Type 1 Induces eIF2α Phosphorylation-Dependent Cellular Translation Shutoff via PERK/GCN2

2021 ◽  
Vol 12 ◽  
Author(s):  
Yuanzhi Liu ◽  
Anchun Cheng ◽  
Mingshu Wang ◽  
Sai Mao ◽  
Xumin Ou ◽  
...  
Keyword(s):  
Virus Type ◽  
Hepatitis A ◽  
Hepatitis A Virus ◽  
Translation Efficiency ◽  
Eif2α Phosphorylation ◽  
Duck Hepatitis ◽  
Cellular Translation ◽  
First Time

Duck hepatitis A virus type 1 (DHAV-1) is one of the most deadly pathogens that endanger the duck industry. Most viruses usually turn off host translation after infection to facilitate viral replication and translation. For the first time report to our knowledge, DHAV-1 can induce eIF2α phosphorylation and inhibit cellular translation in duck embryo fibroblasts (DEFs). Moreover, the activity of DHAV-1 in the cells caused obvious eIF2α phosphorylation, which has nothing to do with the viral protein. Subsequently, we screened two kinases (PERK and GCN2) that affect eIF2α phosphorylation through inhibitors and shRNA. Notably, the role of GCN2 in other picornaviruses has not been reported. In addition, when the phosphorylation of eIF2α induced by DHAV-1 is inhibited, the translation efficiency of DEFs restores to a normal level, indicating that DHAV-1 induced cellular translation shutoff is dependent on eIF2α phosphorylation.

scholarly journals Defective TiO2 Core-Shell Magnetic Photocatalyst Modified with Plasmonic Nanoparticles for Visible Light-Induced Photocatalytic Activity

Catalysts ◽  
2020 ◽  
Vol 10 (6) ◽  
pp. 672 ◽  
Author(s):  
Zuzanna Bielan ◽  
Agnieszka Sulowska ◽  
Szymon Dudziak ◽  
Katarzyna Siuzdak ◽  
Jacek Ryl ◽  
...  
Keyword(s):  
Photocatalytic Activity ◽  
Photoelectron Spectroscopy ◽  
Diffuse Reflectance Spectroscopy ◽  
Phenol Degradation ◽  
Magnetic Core ◽  
Magnetic Photocatalyst ◽  
X Ray ◽  
Transmission Electron ◽  
First Time

In the presented work, for the first time, the metal-modified defective titanium(IV) oxide nanoparticles with well-defined titanium vacancies, was successfully obtained. Introducing platinum and copper nanoparticles (NPs) as surface modifiers of defective d-TiO2 significantly increased the photocatalytic activity in both UV-Vis and Vis light ranges. Moreover, metal NPs deposition on the magnetic core allowed for the effective separation and reuse of the nanometer-sized photocatalyst from the suspension after the treatment process. The obtained Fe3O4@SiO2/d-TiO2-Pt/Cu photocatalysts were characterized by X-ray diffractometry (XRD) and specific surface area (BET) measurements, UV-Vis diffuse reflectance spectroscopy (DR-UV/Vis), X-ray photoelectron spectroscopy (XPS) and transmission electron microscopy (TEM). Further, the mechanism of phenol degradation and the role of four oxidative species (h+, e−, •OH, and •O2−) in the studied photocatalytic process were investigated.

scholarly journals Mechanochemical Synthesis and Structure of the Tetrahydrate and Mesoporous Anhydrous Metforminium(2+)-N,N’-1,4-Phenylenedioxalamic Acid Cocrystal Salt: The Role of Hydrogen Bonding and N→π* Charge Assisted Interactions

2020 ◽  
Author(s):  
Sayuri Chong-Canto ◽  
Efrén V. García-Báez ◽  
Francisco J. Martínez-Martínez ◽  
Ángel Ramos-Organillo ◽  
Itzia I. Padilla-Martínez
Keyword(s):  
Hydrogen Bonding ◽  
Mechanochemical Synthesis ◽  
Water Molecules ◽  
X Ray ◽  
X Ray Crystallography ◽  
Adsorption Desorption ◽  
First Time ◽  
Selective Formation ◽  
Crystallization From Solution

A new cocrystal salt of metformin, an antidiabetic drug, and N,N’-(1,4-phenylene)dioxalamic acid, was synthesized by mechanochemical synthesis, purified by crystallization from solution and characterized by single X-ray crystallography. The structure revealed a salt-type cocrystal composed of one dicationic metformin unit, two monoanionic units of the acid and four water molecules namely H2Mf(HpOXA)2∙4H2O. X-ray powder, IR, 13C-CPMAS, thermal and BET adsorption-desorption analyses were performed to elucidate the structure of the molecular and supramolecurar structure of the anhydrous microcrystalline mesoporous solid H2Mf(HpOXA)2. The results suggest that their structures, conformation and hydrogen bonding schemes are very similar between them. To the best of our knowledge, the selective formation of the monoanion HpOXA⁻, as well as its structure in the solid, is herein reported for the first time. Regular O(-)∙∙∙C(), O(-)∙∙∙N+ and bifacial O(-)∙∙∙C()∙∙∙O(-) of n→* charge-assisted interactions are herein described in H2MfA cocrystal salts which could be responsible of the interactions of metformin in biologic systems. The results, support the participation of n→* charge-assisted interactions independently, and not just as a short contact imposed by the geometric constraint due to the hydrogen bonding patterns.

scholarly journals On the Coronal Activity of RS CVn Systems

1991 ◽  
Vol 130 ◽  
pp. 501-503
Author(s):  
Osman Demircan ◽  
Ethem Derman
Keyword(s):  
Effective Temperature ◽  
Strongly Correlated ◽  
X Ray ◽  
Bolometric Luminosity ◽  
Long Period ◽  
Emission Area ◽  
Coronal Activity ◽  
New Evidence ◽  
Photospheric Radius

An analysis of the X-ray emission of a large sample of single MS stars shows that X-ray luminosity is strongly correlated with the photospheric radius (Fleming et al., 1989) which implies the dependence of activity on bolometric luminosity Lbol, effective temperature Teff, and thus stellar mass M (Micela et al., 1985; Bookbinder et al., 1986). The role of the emission area on the coronal activity of RS CVn systems has been noted independently by Majer et al. (1986), and Demircan (1986).By using new data on some well known RS CVn systems, we produce new evidence that above idea is indeed valid. A plot of X-ray luminosity Lx versus (B – V) for the sample of well known RS CVn systems in Fig. 1 shows that cooler, long period, more evolved systems with larger surface area have stronger X-ray emission.

Growth Morphologies, Fragmentation Patterns, and Hardness in Sodium Hydrogen Urate Monohydrate

2015 ◽  
Vol 1721 ◽  
Author(s):  
A. B. Brune ◽  
W.T. Petuskey
Keyword(s):  
Morphological Data ◽  
X Ray Diffraction ◽  
X Ray ◽  
Sodium Hydrogen ◽  
Dislocation Arrays ◽  
Fragmentation Patterns ◽  
Microscopy Techniques ◽  
First Time

ABSTRACTMechanical properties and new morphological data on synthetic sodium hydrogen urate monohydrate are reported and interpreted. Crystals formed in supersaturated aqueous solutions were identified by powder x-ray diffraction. Intact grains and separate needles were examined by several microscopy techniques, some reported here for the first time. The dominant morphology was spherulite-type, comprising tapered, branched blades (needles) radiating out of a common core. The pointed blade tips were truncated by (011) planes, corresponding to hydrogen-bonded planes. Branching was at about a 5° angle or its multiples, suggesting it accommodated by dislocation arrays at the low angle boundaries, as is often seen in twinning. Vicker’s micro-hardness, extrapolated to zero porosity, was 0.90 GPa, which is greater than the hardness measured by nano-indentation. Present results are anticipated to be useful in interpreting the mechanical characteristics of the material crystallized in vivo and its action concerning gout, and affording inferences on the role of the milieu on morphologies, fragmentation, and hardness.

Effects on the amorphous Ga2O3 film surfaces by sub-IB-metal-nano-layers

MRS Advances ◽  
2019 ◽  
Vol 4 (5-6) ◽  
pp. 285-292
Author(s):  
L. I. Juárez-Amador ◽  
M. Galván-Arellano ◽  
Y. M. Hernández-Rodríguez ◽  
J. A. Andraca-Adame ◽  
G. Romero-Paredes ◽  
...  
Keyword(s):  
Room Temperature ◽  
Rf Sputtering ◽  
Sem Analysis ◽  
X Ray Diffraction ◽  
Amorphous Films ◽  
X Ray ◽  
Plasmon Frequency ◽  
First Time ◽  
Amorphous Character

AbstractThis work reports by the first time a method to control the geometry of Ga2O3 films nanocrystallites at 350 °C. The formation of controlled shaped nano-crystallites of γ-Ga2O3 from amorphous Ga2O3 films grown by RF-Sputtering at room temperature driven by nano-layers of group IB metals (Cu, Ag or Au) is studied. The reported results can be explained by the role of subsurface metal nano-layers and the non-equilibrium nature of the sputtering processes. To study the effects on the surface structure and their optical properties arrays of amorphous-Ga2O3/IB-metal/amorphous-Ga2O3 were annealed in dry N2 atmosphere at 350 °C by 50, 100 and 150 min. The experimental results can be explained by the evolution of the amorphous character of the films amorphous films towards the nanocrystalline γ-Ga2O3 phase driven by the metal nano-layer seed nature. As the annealing time was increased the transition from amorphous-Ga2O3 to the nanocrystalline γ-Ga2O3 phase was detected by X-ray diffraction analysis. The transition to the nanocrystalline γ-Ga2O3 is demonstrated by the formation of octahedral, triangle and ball shape nanocrystallites with sizes of ∼5 to 50 nm according to FE-SEM analysis. The influence of the metal nano-layer is clearly seen by the shift of the plasmon frequency resonance produced by the Ga2O3/IB-metal/Ga2O3 arrays in the region from 400 to 600 nm caused by the modification of the interface Ga2O3/IB-metal produced by the applied annealing stages.

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