publicationDate
stringlengths
1
2.79k
title
stringlengths
1
36.5k
abstract
stringlengths
1
37.3k
id
stringlengths
9
47
2014-02-11
Iron-line and continuum variations in the XMM-Newton and Suzaku spectra of the neutron-star low-mass X-ray binary 4U 1636-53
We used six simultaneous XMM-Newton and Rossi X-ray Timing Explorer plus five Suzaku observations to study the continuum spectrum and the iron emission line in the neutron-star low-mass X-ray binary 4U 1636-53. We modelled the spectra with two thermal components (representing the accretion disc and boundary layer), a C...
1402.2350v1
2014-06-16
Simulation Studies for Electromagnetic Design of INO ICAL Magnet and its Response to Muons
The iron calorimeter (ICAL) detector at the India-based Neutrino Observatory (INO) will be used to measure neutrino mass hierarchy. The magnet in the ICAL detector will be used to distinguish the {\mu^-} and {\mu^+} events induced by {\nu_{\mu}} and {\bar{\nu_{\mu}}}, respectively. Due to the importance of the magnet i...
1406.3965v3
2014-08-20
Nuclear inputs of key iron isotopes for core-collapse modeling and simulation
From the modeling and simulation results of presupernova evolution of massive stars, it was found that isotopes of iron, $^{54,55,56}$Fe, play a significant role inside the stellar cores, primarily decreasing the electron-to-baryon ratio ($Y_{e}$) mainly via electron capture processes thereby reducing the pressure supp...
1408.4534v1
2014-09-08
Electronic structure in one-Fe Brillouin zone of iron-pnictide superconductor CsFe$_2$As$_2$
The multiband nature of iron-pnictide superconductors is one of the keys to the understanding of their intriguing behavior. The electronic and magnetic properties heavily rely on the multiband interactions between different electron and hole pockets near the Fermi level. At the fundamental level, though many theoretica...
1409.2300v2
2014-11-20
Significant contribution of As 4p orbitals to the low-lying electronic structure of 112-type iron-based superconductor Ca0.9La0.1FeAs2
We report a systematic polarization-dependent angle-resolved photoemission spectroscopy study of the three-dimensional electronic structure of the recently discovered 112-type iron-based superconductor Ca1-xLaxFeAs2 (x = 0.1). Besides the commonly reported three hole-like and two electron-like bands in iron-based super...
1411.5525v1
2015-01-23
Tensile strain-induced softening of iron at high temperature
In weakly ferromagnetic materials, already small changes in the atomic configuration triggered by temperature or chemistry can alter the magnetic interactions responsible for the non-random atomic-spin orientation. Different magnetic states, in turn, can give rise to substantially different macroscopic properties. A cl...
1501.05774v2
2015-01-23
Quasiparticles in Iron Silicides: GW versus LDA
The angle-resolved photoemission spectroscopy, ARPES, is able to measure both the spectra and spectral weights of the quasiparticles in solids. Although it is common to interpret the band structure obtained within the density-functional-theory based methods as quasi-particle spectra, these methods are not able to provi...
1501.05898v3
2015-01-27
Direct observation of nanoscale interface phase in the superconducting chalcogenide K$_{x}$Fe$_{2-y}$Se$_2$ with intrinsic phase separation
We have used scanning micro x-ray diffraction to characterize different phases in superconducting K$_{x}$Fe$_{2-y}$Se$_2$ as a function of temperature, unveiling the thermal evolution across the superconducting transition temperature (T$_c\sim$32 K), phase separation temperature (T$_{ps}\sim$520 K) and iron-vacancy ord...
1501.06745v1
2015-02-26
Strong Interplay between Stripe Spin Fluctuations, Nematicity and Superconductivity in FeSe
Elucidating the microscopic origin of nematic order in iron-based superconducting materials is important because the interactions that drive nematic order may also mediate the Cooper pairing. Nematic order breaks fourfold rotational symmetry in the iron plane, which is believed to be driven by either orbital or spin de...
1502.07544v1
2015-03-18
Broad Iron Emission from Gravitationally Lensed Quasars Observed by Chandra
Recent work has demonstrated the potential of gravitationally lensed quasars to extend measurements of black hole spin out to high-redshift with the current generation of X-ray observatories. Here we present an analysis of a large sample of 27 lensed quasars in the redshift range 1.0<z<4.5 observed with Chandra, utiliz...
1503.05255v1
2015-05-12
Experimental Observation of Incoherent-Coherent Crossover and Orbital Dependent Band Renormalization in Iron Chalcogenide Superconductors
The level of electronic correlation has been one of the key questions in understanding the nature of superconductivity. Among the iron-based superconductors, the iron chalcogenide family exhibits the strongest electron correlations. To gauge the correlation strength, we performed systematic angle-resolved photoemission...
1505.03074v1
2015-06-02
Development of high-performance iron-based superconducting wires and tapes
Conventional powder-in-tube (PIT) method has been the most effective technique for fabricating iron-based superconducting wires and tapes. Tremendous advances have been made during the last few years, especially for 122 family pnictide tapes. Here we review some of the most recent and significant developments in making...
1506.00792v2
2015-07-06
A chemical trompe-l'œil: no iron spread in the globular cluster M22
We present the analysis of high-resolution spectra obtained with UVES and UVES-FLAMES at the Very Large Telescope of 17 giants in the globular cluster M22, a stellar system suspected to have an intrinsic spread in the iron abundance. We find that when surface gravities are derived spectroscopically (by imposing to obta...
1507.01596v1
2015-07-09
O and Fe abundance correlations and distributions inferred for the thick and thin disk
A linear [Fe/H]-[O/H] relation is found for different stellar populations in the Galaxy (halo, thick disk, thin disk) from a data sample obtained in a recent investigation (Ram{\'\i}rez et al. 2013). These correlations support previous results inferred from poorer samples: stars display a "main sequence" expressed as [...
1507.02405v1
2015-08-07
Spin reorientation driven by the interplay between spin-orbit coupling and Hund's rule coupling in iron pnictides
In most magnetically-ordered iron pnictides, the magnetic moments lie in the FeAs planes, parallel to the modulation direction of the spin stripes. However, recent experiments in hole-doped iron pnictides have observed a reorientation of the magnetic moments from in-plane to out-of-plane. Interestingly, this reorientat...
1508.01763v4
2015-08-26
Spatial competition of the ground states in 1111 iron pnictides
Using nuclear quadrupole resonance, the phase diagram of 1111 $R$FeAsO$_{1-x}$F$_x$ ($R$$=$La, Ce, Sm) iron pnictides is constructed as a function of the local charge distribution in the paramagnetic state, which features low-doping-like (LD-like) and high-doping-like (HD-like) regions. Compounds based on magnetic rare...
1508.06532v1
2015-10-04
To the measurement of the radius via an electron scattering
We propose an experiment for an accurate measurement of the proton radius. A key feature of our proposal is an iron-free magnetic spectrometer. Projected systematics uncertainties will allow a 1% level accuracy for the $r_p$ value.
1510.00890v1
2015-10-28
Superconducting state in Fe-based materials and spin-fluctuation theory of pairing
Short review of the spin-fluctuation theory of superconductive pairing in iron-based pnictides and chalcogenides.
1510.08279v1
2015-11-02
Comment on 'A new nanoscale metastable iron phase in carbon steels'
We show that the selected area diffraction patterns presented in a recent paper (T. Liu et al. Sci. Rep. 2015 5, 15331) do not prove the existence of a new hexagonal phase in martensitic steels. They can be actually simulated by twin effects.
1511.00591v1
2015-12-08
Photodisintegrated gamma rays and neutrinos from heavy nuclei in the gamma-ray burst jet of GRB 130427A
Detection of ~ 0.1-70 GeV prompt gamma-ray emission from the exceptionally bright gamma-ray burst (GRB) 130427A by the Fermi-Large Area Telescope provides an opportunity to explore the physical processes of GeV gamma-ray emission from the GRB jets. In this work we discuss interactions of Iron and Oxygen nuclei with obs...
1512.02434v3
2015-12-10
Robust Zero Energy Bound States Localized at Magnetic Impurities in Iron-based Superconductors
We investigate the effect of spin-orbit coupling on the in-gap bound states localized at magnetic impurities in multi-band superconductors with unconventional (sign-changed) and conventional (sign-unchanged) $s$-wave pairing symmetry, which may be relevant to iron-based superconductors. Without spin-orbit coupling, for...
1512.03450v2
2015-12-18
Seismic waves damping with arrays of inertial resonators
We investigate the elastic stop band properties of a theoretical cubic array of iron spheres connected to a bulk of concrete via iron or rubber ligaments. Each sphere can move freely within a surrounding air cavity, but ligaments couple it to the bulk and further facilitate bending and rotational motions. Associated lo...
1512.06078v2
2016-04-13
Magnetic properties and pairing tendencies of the iron-based superconducting ladder BaFe$_2$S$_3$: combined ab initio and density matrix renormalization group study
The recent discovery of superconductivity under high pressure in the two-leg ladder compound BaFe$_2$S$_3$ [H. Takahashi et al., Nature Materials 14, 1008 (2015)] opens a broad avenue of research, because it represents the first report of pairing tendencies in a quasi one-dimensional iron-based high critical temperatur...
1604.03621v2
2016-05-10
A unified model of grain alignment: radiative alignment of interstellar grains with magnetic inclusions
The radiative torque (RAT) alignment of interstellar grains with ordinary paramagnetic susceptibilities has been supported by earlier studies. The alignment of such grains depends on the so-called RAT parameter $q^{\max}$ that is determined by the grain shape. In this paper, we elaborate our model of RAT alignment for ...
1605.02828v2
2016-06-08
Observation of a Hidden Hole-Like Band Approaching the Fermi Level in K-Doped Iron Selenide Superconductor
One of the ultimate goals of the study of iron-based superconductors is to identify the common feature that produces the high critical temperature (Tc). In the early days, based on a weak-coupling viewpoint, the nesting between hole- and electron-like Fermi surfaces (FSs) leading to the so-called $s\pm$ state was consi...
1606.02405v1
2016-06-27
Coordinated Analysis of Two Graphite Grains from the CO3.0 LAP 031117 Meteorite: First Identification of a CO Nova Graphite and a Presolar Iron Sulfide Subgrain
Presolar grains constitute remnants of stars that existed before the formation of the solar system. In addition to providing direct information on the materials from which the solar system formed, these grains provide ground-truth information for models of stellar evolution and nucleosynthesis. Here we report the in-si...
1606.08310v1
2016-07-05
Delayed hepatic uptake of multi-phosphonic acid poly(ethylene glycol) coated iron oxide measured by real-time Magnetic Resonance Imaging
We report on the synthesis, characterization, stability and pharmacokinetics of novel iron based contrast agents for magnetic resonance imaging (MRI). Statistical copolymers combining multiple phosphonic acid groups and poly(ethylene glycol) (PEG) were synthesized and used as coating agents for 10 nm iron oxide nanocry...
1607.01656v1
2016-07-11
A quasi-periodic modulation of the iron line centroid energy in the black hole binary H 1743-322
Accreting stellar-mass black holes often show a `Type-C' quasi-periodic oscillation (QPO) in their X-ray flux, and an iron emission line in their X-ray spectrum. The iron line is generated through continuum photons reflecting off the accretion disk, and its shape is distorted by relativistic motion of the orbiting plas...
1607.02866v1
2016-12-20
Magnetism of PrFeAsO parent compound for iron-based superconductors: Mössbauer spectroscopy study
Moessbauer spectroscopy measurements were performed for the temperature range between 4.2 K and 300 K in a transmission geometry applying 14.41-keV resonant line in 57Fe for PrFeAsO the latter being a parent compound of the iron-based superconductors belonging to the '1111' family. It was found that an itinerant 3d mag...
1612.06776v3
2017-04-06
Towards Picogram Detection of Superparamagnetic Iron-Oxide Particles Using a Gradiometric Receive Coil
Superparamagnetic iron-oxide nanoparticles can be used in a variety of medical applications like vascular or targeted imaging. Magnetic particle imaging (MPI) is a promising tomographic imaging technique that allows visualizing the 3D nanoparticle distribution concentration in a non-invasive manner. The two main streng...
1704.01789v2
2017-07-10
Diagnosing the kinematics of the tori in active galactic nuclei with the velocity-resolved reverberation mapping of the narrow iron K$α$ line
The properties of the dusty tori in active galactic nuclei (AGNs) have been investigated in detail, mainly focusing on the geometry and components; however, the kinematics of the torus is still not clear. The narrow iron K$\alpha$ line at 6.4 keV is thought to be produced by the X-ray reflection from the torus. Thus, t...
1707.02665v1
2017-08-15
Effects of ultrasound waves intensity on the removal of Congo red color from the textile industry wastewater by Fe3O4@TiO2 core-shell nanospheres
Environmental pollutants, such as colors from the textile industry, affect water quality indicators like color, smell, and taste. These substances in the water cause the obstruction of filters and membranes and thereby reduce the efficiency of advanced water treatment processes. In addition, they are harmful to human h...
1708.04683v2
2017-09-21
Orbital loop currents in iron-based superconductors
We show that the antiferromagnetic state commonly observed in the phase diagrams of the iron-based superconductors necessarily triggers loop currents characterized by charge transfer between different Fe $ 3d $ orbitals. This effect is rooted on the glide-plane symmetry of these materials and on the existence of an ato...
1709.07266v2
2017-10-13
A Suzaku View of Accretion Powered X-ray Pulsar GX 1+4
We present results obtained from a Suzaku observation of the accretion powered X-ray pulsar GX 1+4. Broad-band continuum spectrum of the pulsar was found to be better described by a simple model consisting of a blackbody component and an exponential cutoff power-law than the previously used compTT continuum model. Thou...
1710.04820v2
2017-12-13
Quantum effects on dislocation motion from Ring-Polymer Molecular Dynamics
Quantum motion of atoms known as zero-point vibrations is recognized to be important at low temperatures in condensed matter systems comprised of light atoms or ions, affecting such properties and behaviors as proton-transfer reactions, vibrational spectra of water and ice, and mechanical properties of low temperature ...
1712.04629v2
2017-12-19
Cysteine and cystine adsorption on FeS$_{2}$(100)
Iron pyrite (FeS$_{2}$) is the most abundant metal sulfide on Earth. Owing to its reactivity and catalytic activity, pyrite has been studied in various research fields such as surface science, geochemistry, and prebiotic chemistry. Importantly, native iron-sulfur clusters are typically coordinated by cysteinyl ligands ...
1712.06785v1
2018-01-18
Iron-peak elements Sc, V, Mn, Cu and Zn in Galactic bulge globular clusters
Globular clusters are tracers of the history of star formation and chemical enrichment in the early Galaxy. Their abundance pattern can help understanding their chemical enrichment processes. In particular, the iron-peak elements have been relatively little studied so far in the Galactic bulge. The abundances of iron-p...
1801.06157v1
2018-02-17
J0023+0307: A mega metal-poor dwarf star from SDSS/BOSS
Only a handful of stars have been identified with an iron abundance [Fe/H]<-5, and only one at [Fe/H]<-7. These stars have very large carbon-to-iron ratios, with A(C)~7.0, most likely due to fallback in core-collapse supernovae, which makes their total metallicity Z much higher than their iron abundances. The failure t...
1802.06240v2
2018-03-26
The chemical composition of NGC5824, a globular cluster without iron spread but with an extreme Mg-Al anticorrelation
NGC5824 is a massive Galactic globular cluster suspected to have an intrinsic spread in its iron content, according to the strength of the calcium triplet lines. We present chemical abundances of 117 cluster giant stars using high-resolution spectra acquired with the multi-object spectrograph FLAMES. The metallicity di...
1803.09759v1
2018-04-30
X-ray short-time lags in the Fe-K energy band produced by scattering clouds in active galactic nuclei
X-rays illuminating the accretion disc in active galactic nuclei give rise to an iron K line and its associated reflection spectrum which are lagged behind the continuum variability by the light-travel time from the source to the disc. The measured lag timescales in the iron band can be as short as $\sim R_g/c$, where ...
1805.00046v1
2018-07-16
Revisiting the iron abundance in the hyper iron-poor star HE$~$1327-2326 with UV COS/$HST$ data
We present a new iron abundance analysis of the hyper metal-poor star HE$~$1327-2326, based on Fe II lines detected in its UV spectral range for the first time. In a Cosmic Origins Spectrograph (COS) spectrum, five new Fe II lines could be measured. A Si I line was also detected for the first time. We determine a 1D Lo...
1807.06153v1
2019-02-13
Strain Controlling Catalytic Efficiency of Water Oxidation for Ni1-xFexOOH alloy
A catalyst surface may be exposed to strain due to application of load or interfacing with a substrate with large lattice mismatch. In order to test the effect of strain on catalytic efficiency, we use Density Functional Theory +U (DFT+U) to model water oxidation on expanded and contracted surfaces of the Ni1-xFexOOH a...
1902.04788v1
2019-03-27
Design, Fabrication and Characterization of FeAl-based Metallic-Intermetallic Laminate (MIL) Composites
FeAl-based MIL composites of various iron alloys were fabricated with an innovative 'multiple-thin-foil' configuration and 'two-stage reaction' strategy.
1903.11724v1
2019-04-02
The Wolf-Rayet Stellar Response To The Iron Opacity Bump: Envelope Inflation, Winds, and Microturbulence
Early-type Wolf-Rayet(WR) stellar models harbor a super-Eddington layer in their outer envelopes due to a prominent iron opacity bump. In the past few decades, one-dimensional hydrostatic and time-steady hydrodynamic models have suggested a variety of WR responses to a super-Eddington force including envelope inflation...
1904.01703v1
2019-04-30
Scalable Majorana vortex modes in iron-based superconductors
A vortex in an s-wave superconductor with a surface Dirac cone can trap a Majorana bound state with zero energy leading to a zero-bias peak (ZBP) of tunneling conductance. The iron-based superconductor FeTe$_x$Se$_{1-x}$ is one of the material candidates hosting these Majorana vortex modes. It has been observed by rece...
1904.13374v3
2019-06-18
X-ray reprocessing: Through the eclipse spectra of high mass X-ray binaries with XMM-Newton
The study of X-ray reprocessing is one of the key diagnostic tools to probe the environment in X-ray binary systems. One difficult aspect of studying X-ray reprocessing is the presence of much brighter primary radiation from the compact star together with the reprocessed radiation. In contrast for eclipsing systems, th...
1906.07739v1
2019-11-13
Superparamagnetic iron oxide nanoparticles conjugated with doxorubicin for targeting breast cancer
Development of the next generations of cancer therapy modalities is currently a crucial requirement of oncology. Advances in nanotechnology are bringing us closer to the development of dual and multifunctional nanoparticles that are challenging the traditional distinction between diagnostic and treatment agents. The ch...
1911.05378v1
2020-03-06
Mössbauer parameters of $^{57}$Fe substituents in the topological insulator $Bi_2Se_3$
$^{57}$Fe M\"ossbauer spectroscopy can probe several \emph{local} structural, electronic and magnetic properties of Fe-containing systems. However, to establish a direct relationship between these properties and a system's geometric structure, the experimental M\"ossbauer parameters need to be analyzed \emph{via} elect...
2003.03458v1
2020-04-01
Phase transitions and spin-state of iron in FeO at the conditions of Earth's deep interior
Iron-bearing oxides undergo a series of pressure-induced electronic, spin and structural transitions that can cause seismic anomalies and dynamic instabilities in Earth's mantle and outer core. We employ x-ray diffraction and x-ray emission spectroscopy along with state-of-the-art density functional plus dynamical mean...
2004.00652v2
2020-06-05
Planetary mass-radius relations across the galaxy
Planet formation theory suggests that planet bulk compositions are likely to reflect the chemical abundance ratios of their host star's photosphere. Variations in the abundance of particular chemical species in stellar photospheres between different galactic stellar populations demonstrate that there are differences am...
2006.03601v2
2020-10-01
Near L-Edge Single and Multiple Photoionization of Doubly Charged Iron Ions
Using the photon-ion merged-beams technique at a synchrotron light source, we have measured relative cross sections for single and up to five-fold photoionization of Fe$^{2+}$ ions in the energy range 690--920 eV. This range contains thresholds and resonances associated with ionization and excitation of $2p$ and $2s$ e...
2010.00473v1
2020-10-13
Chemical Fingerprints of Formation in Rocky Super-Earths' Data
The composition of rocky exoplanets in the context of stars' composition provides important constraints to formation theories. In this study, we select a sample of exoplanets with mass and radius measurements with an uncertainty <25% and obtain their interior structure. We calculate compositional markers, ratios of iro...
2010.06480v1
2020-11-16
Role of anion in the pairing interaction of iron-based superconductivity
High-temperature iron-based superconductivity develops in a structure with unusual lattice-orbital geometry, based on a planar layer of Fe atoms with 3d orbitals and tetrahedrally coordinated by anions. Here we elucidate the electronic role of anions in the iron-based superconductors utilizing state-of-the-art scanning...
2011.07701v1
2020-11-26
Oxidising and carburising catalyst conditioning for the controlled growth and transfer of large crystal monolayer hexagonal boron nitride
Hexagonal boron nitride (h-BN) is well-established as a requisite support, encapsulant and barrier for 2D material technologies, but also recently as an active material for applications ranging from hyperbolic metasurfaces to room temperature single-photon sources. Cost-effective, scalable and high quality growth techn...
2011.13176v1
2020-12-23
Hot electron relaxation in normal state of iron pnictides: memory function approach
This study leads to the investigation of the non-equilibrium electron relaxation in the normal state of iron pnictides. Here we consider the relaxation of electrons due to their coupling with magnons and phonons in the metallic state of iron pnictides using the memory function approach. In the present model, electrons ...
2012.12650v1
2021-02-10
Influence of microstructure and atomic-scale chemistry on iron ore reduction with hydrogen at 700°C
With 1.85 billion tons produced per year, steel is the most important material class in terms of volume and environmental impact. While steel is a sustainability enabler, for instance through lightweight design, magnetic devices, and efficient turbines, its primary production is not. For 3000 years, iron has been reduc...
2102.05654v1
2021-04-06
Early volatile depletion on planetesimals inferred from C-S systematics of iron meteorite parent bodies
During the formation of terrestrial planets, volatile loss may occur through nebular processing, planetesimal differentiation, and planetary accretion. We investigate iron meteorites as an archive of volatile loss during planetesimal processing. The carbon contents of the parent bodies of magmatic iron meteorites are r...
2104.02706v1
2021-05-15
Two-step nucleation of the Earth's inner core
It has long been assumed the Earth's solid inner core started to grow when molten iron cooled to its melting point. However, the nucleation mechanism, which is a necessary step of crystallization, has not been well understood. Recent studies found it requires an unrealistic degree of undercooling to nucleate the stable...
2105.07296v2
2021-06-04
Disentangling Dense Multi-Cable Knots
Disentangling two or more cables requires many steps to remove crossings between and within cables. We formalize the problem of disentangling multiple cables and present an algorithm, Iterative Reduction Of Non-planar Multiple cAble kNots (IRON-MAN), that outputs robot actions to remove crossings from multi-cable knott...
2106.02252v1
2021-09-17
Quantum hardware calculations of periodic systems with partition-measurement symmetry verification: simplified models of hydrogen chain and iron crystals
Running quantum algorithms on real hardware is essential for understanding their strengths and limitations, especially in the noisy intermediate scale quantum (NISQ) era. Herein we focus on the practical aspect of quantum computational calculations of solid-state crystalline materials based on theory developed in our g...
2109.08401v4
2021-09-23
Large Exotic Spin Torques in Antiferromagnetic Iron Rhodium
Spin torque is a promising tool for driving magnetization dynamics for novel computing technologies. These torques can be easily produced by spin-orbit effects, but for most conventional spin source materials, a high degree of crystal symmetry limits the geometry of the spin torques produced. Magnetic ordering is one w...
2109.11108v1
2021-12-29
Composition of super-Earths, super-Mercuries, and their host stars
Because of their common origin, it was assumed that the composition of planet building blocks should, to a first order, correlate with stellar atmospheric composition, especially for refractory elements. In fact, information on the relative abundance of refractory and major rock-forming elements such as Fe, Mg, Si has ...
2112.14512v1
2022-01-06
Ironing out the details of unconventional superconductivity
Superconductivity is a remarkably widespread phenomenon observed in most metals cooled down to very low temperatures. The ubiquity of such conventional superconductors, and the wide range of associated critical temperatures, is readily understood in terms of the celebrated Bardeen-Cooper-Schrieffer (BCS) theory. Occasi...
2201.02095v1
2022-03-21
White Dwarf Photospheric Abundances in Cataclysmic Variables -- II. White Dwarfs With and Without a Mask
Taking advantage of the now available Gaia EDR3 parallaxes, we carry out an archival {\it Hubble Space Telescope} (HST) far ultraviolet spectroscopic analysis of 10 cataclysmic variable systems, including 5 carefully selected eclipsing systems. We obtain accurate white dwarf (WD) masses and temperatures, in excellent a...
2203.11020v1
2022-04-11
Forming Iron-rich Planets with Giant Impacts
We investigate mantle stripping giant impacts (GI) between super-Earths with masses between 1 M$_{\oplus}$ and 20 M$_{\oplus}$. We infer new scaling laws for the mass of the largest fragment and its iron mass fraction, as well as updated fitting coefficients for the critical specific impact energy for catastrophic disr...
2204.04925v3
2023-01-11
Evolution of the spin dynamics during freezing in the spin-glass Fe$_{x}$Cr$_{1-x}$
In the iron--chromium system, Fe$_{x}$Cr$_{1-x}$, a wide dome of spin-glass behavior emerges when the ferromagnetism of iron is suppressed and the antiferromagnetism of chromium emerges as a function of increasing iron content $x$. As both, the high-temperature state and the characteristic cluster size vary as a functi...
2301.04495v1
2023-03-12
Competing Magnetic Interactions and Field-Induced Metamagnetic Transition in Highly Crystalline Phase-Tunable Iron Oxide Nanorods
The inherent existence of multi phases in iron oxide nanostructures highlights the significance of them being investigated deliberately to understand and possibly control the phases. Here, the effects of annealing at 250 0C with a variable duration on the bulk magnetic and structural properties of high aspect ratio bi-...
2303.06684v1
2023-03-24
Early phases of the Galaxy from the chemical imprint on the iron-poor stars J0815+4729 and J0023+0307
We have been exploring large spectroscopic databases such as SDSS to search for unique stars with extremely low iron content with the goal of extracting detailed information from the early phases of the Galaxy. We recently identified two extremely iron-poor dwarf stars J0815+4729 (Aguado et al. 2018a) and J0023+0307 (A...
2303.14142v1
2023-10-27
Emergent spin-glass state in the doped Hund's metal CsFe2As2
Hund's metal is one kind of correlated metal, in which the electronic correlation is strongly influenced by the Hund's interaction. At high temperatures, while the charge and orbital degrees of freedom are quenched, the spin degrees of freedom can persist in terms of frozen moments. As temperature decreases, a coherent...
2310.17858v1
2023-11-07
Direct reduction of iron-ore with hydrogen in fluidized beds: A coarse-grained CFD-DEM-IBM study
Hydrogen metallurgy technology uses hydrogen as the reducing agent instead of carbon reduction, which is one of the important ways to reduce carbon dioxide emissions and ensure the green and sustainable development of iron and steel industry. Due to the advantages of high gas-solid contact efficiency and outstanding ma...
2311.03908v1
2023-12-22
Broken inversion symmetry in van der Waals topological ferromagnetic metal iron germanium telluride
Inversion symmetry breaking is critical for many quantum effects and fundamental for spin-orbit torque, which is crucial for next-generation spintronics. Recently, a novel type of gigantic intrinsic spin-orbit torque has been established in the topological van-der-Waals (vdW) magnet iron germanium telluride. However, i...
2312.14384v1
2024-01-05
The Fate of Primary Iron Sulfides in the CM1 Carbonaceous Chondrites: Effects of Advanced Aqueous Alteration on Primary Components
We have carried out a SEM-EPMA-TEM study to determine the textures and compositions of relict primary iron sulfides and their alteration products in a suite of moderately to heavily-altered CM1 carbonaceous chondrites. We observed four textural groups of altered primary iron sulfides: 1) pentlandite+phyllosilicate (2P)...
2401.02932v1
2024-02-19
Breaks in the Hall-Petch Relationship after Severe Plastic Deformation of Magnesium, Aluminum, Copper, and Iron
Strengthening by grain refinement via the Hall-Petch mechanism and softening by nanograin formation via the inverse Hall-Petch mechanism have been the subject of argument for decades, particularly for ultrafine-grained materials. In this study, the Hall-Petch relationship is examined for ultrafine-grained magnesium, al...
2402.11798v1
2024-02-19
Ironing allocations
I propose a new approach to solving standard screening problems when the monotonicity constraint binds. A simple geometric argument shows that when virtual values are quasi-concave, the optimal allocation can be found by appropriately truncating the solution to the relaxed problem. I provide a simple algorithm for find...
2402.11881v1
1994-01-24
The Contribution of the Obscuring Torus to the X--Ray Spectrum of Seyfert Galaxies: A Test for the Unification Model
The presence of an obscuring torus around the nucleus of Seyfert galaxies, as supposed in the popular unification scheme, can strongly modify the X--ray spectrum for both type 1 and 2 Seyfert galaxies. We find that if the torus is Compton thick, it can scatter at small angles a significant fraction of the nuclear radia...
9401044v1
1996-08-26
Variability of the iron K-emission line in the Seyfert 1 galaxy NGC 3516
We present strong evidence for variability of the flux of the iron K$\alpha$ emission line in the Seyfert 1 galaxy, NGC 3516. Two ASCA observations, separated by $\sim 1$~yr, showed a marked decrease in continuum flux by $\sim 60$~per cent. The flux in the broad, iron K$\alpha$ line decreased by the same factor in this...
9608171v1
1997-03-25
The iron K line complex in NGC1068: implications for X-ray reflection in the nucleus
We report a new analysis of ASCA data on the iron K line complex in NGC1068. The line complex basically consists of three components, as previously reported. A weak red wing of the 6.4 keV fluoresence iron K line is found. A plausible explanation is Compton scattering in optically thick, cold matter which can be identi...
9703159v1
1997-07-07
Special relativistic effects on the strength of the fluorescent K-alpha iron line from black hole accretion disks
The broad iron K$\alpha$ emission line, commonly seen in the X-ray spectrum of Seyfert nuclei, is thought to originate when the inner accretion disk is illuminated by an active disk-corona. We show that relative motion between the disk and the X-ray emitting material can have an important influence on the observed equi...
9707082v1
1998-02-05
How Abundant is Iron in the Core of the Perseus Cluster?
The analysis of Perseus data collected with the Medium Energy Concentrator Spectrometer (MECS) on board Beppo-SAX shows that the ratio of the flux of the 8 keV line complex (dominated by Fe K$_{\beta}$ emission) over the 6.8 keV line complex (dominated by Fe K$_{\alpha}$ emission) is significantly larger than predicted...
9802067v1
1999-02-18
The contribution of AGN to the X-ray background: the effect of iron features
The contribution of the iron emission line, commonly detected in the X-ray spectra of Seyfert (Sey) galaxies, to the cosmic X-ray background (XRB) spectrum is evaluated in the framework of the XRB synthesis models based on AGN unification schemes. To derive the mean line properties, we have carried out a search in the ...
9902256v1
1999-06-21
Galactic Ultra-High-Energy Cosmic Rays
The absence of the expected GZK cutoff strongly challenges the notion that the highest-energy cosmic rays are of distant extragalactic origin. We discuss the possibility that these ultra-high-energy events originate in our Galaxy and propose that they may be due to iron nuclei accelerated from young, strongly magnetic ...
9906338v1
1999-08-25
Reprocessed emission from warped accretion discs with application to X-ray iron line profiles
Flourescent iron line profiles currently provide the best diagnostic for active galactic nuclei (AGN) engine geometries. Here we construct a method for calculating the relativistic iron line profile from an arbitrarily warped accretion disc, illuminated from above and below by hard X-ray sources. This substantially gen...
9908275v1
1999-11-19
Revised Stroemgren metallicity calibration for red giants
A new calibration of the Stroemgren (b-y),m_1 diagram in terms of iron abundance of red giants is presented. This calibration is based on a homogeneous sample of giants in the globular clusters omega Centauri, M22, and M55 as well as field giants from the list of Anthony-Twarog & Twarog (1998). Towards high metalliciti...
9911387v1
1999-12-01
Line emission from gamma-ray burst environments
The time and angle dependent line and continuum emission from a dense torus around a cosmological gamma-ray burst source is simulated, taking into account photoionization, collisional ionization, recombination, and electron heating and cooling due to various processes. The importance of the hydrodynamical interaction b...
9912030v2
1999-12-10
Ultra-High Energy Cosmic Rays from Young Neutron Star Winds
The long-held notion that the highest-energy cosmic rays are of distant extragalactic origin is challenged by observations that events above $\sim 10^{20}$ eV do not exhibit the expected high-energy cutoff from photopion production off the cosmic microwave background. We suggest that these unexpected ultra-high-energy ...
9912240v2
2000-01-19
Observing the effects of strong gravity with future X-ray missions
Spectroscopy of the broad iron iron with ASCA and BeppoSAX has up opened the innermost regions of accreting black hole systems to detailed study. In this contribution, I discuss how observations with future X-ray missions will extend these studies and all us to observationally address issues which are currently only in...
0001324v1
2000-10-11
Discovery of a redshifted Iron K-line in the X-ray afterglow of GRB 000214
We report the detection (3 sigma significance level) of a strong iron emission line in the X-ray spectrum of the afterglow of GRB 000214 (``Valentine's Day Burst'') observed by BeppoSAX. An emission line feature was observed with a centroid energy of 4.7+/-0.2 keV which, if interpreted as K-alpha emission from hydrogen...
0010221v1
2000-10-20
First XMM-Newton observations of a cataclysmic variable II: the X-ray spectrum of OY Car
We present XMM-Newton X-ray spectra of the disc accreting cataclysmic variable OY Car, which were obtained during the performance verification phase of the mission. These data were taken 4 days after a short outburst. In the EPIC spectra we find strong iron Kalpha emission with weaker iron Kbeta emission together with ...
0010416v1
2000-10-20
XMM-Newton observations of the cluster of galaxies Sersic 159-03
The cluster of galaxies Sersic 159-03 was observed with the XMM-Newton X-ray observatory as part of the Guaranteed Time program. X-ray spectra taken with the EPIC and RGS instruments show no evidence for the strong cooling flow derived from previous X-ray observations. There is a significant lack of cool gas below 1.5 ...
0010423v2
2000-10-25
The unique rapid variabilities of the iron K$α$ line profiles in NGC 4151
We present a detailed analysis of the iron K$\alpha$ line variabilities in NGC 4151 by using long ASCA observation data obtained in May 1995. Despite the relatively small amplitude variations in the continuum flux, the iron K$\alpha$ line flux and profile show dramatic variations. Particularly, the line profile changes...
0010524v1
2000-11-28
Stellar Pollution in the Solar Neighborhood
We study spectroscopically determined iron abundances of 642 solar-type stars to search for the signature of accreted iron-rich material. We find that the metallicity [Fe/H] of a subset of 466 main sequence stars, when plotted as a function of stellar mass, mimics the pattern seen in lithium abundances in open clusters...
0011530v1
2001-03-23
A Measurement of the Flux of Cosmic Ray Iron at 5 x 10^13 eV
We present results from the initial flight of our Balloon Air CHerenkov (BACH) payload. BACH detects air Cherenkov radiation from cosmic ray nuclei as coincident flashes in two optical modules. The flight (dubbed PDQ BACH) took place on April 22, 1998 from Ft. Sumner, New Mexico. During an exposure of 2.75 hours, with ...
0103397v1
2001-07-18
Non-Equilibrium Ionization States of GRB Environments
Iron spectral features are thought to be the best tracer of a progenitor of gamma-ray bursts (GRBs). The detections of spectral features such as an iron line and/or a Radiative Recombination edge and Continuum (RRC) were reported in four X-ray afterglows of GRBs. However their properties were different each other burst...
0107330v1
2001-09-13
High Redshift Quasars and Star Formation in the Early Universe
In order to derive information on the star formation history in the early universe we observed 6 high-redshift (z=3.4) quasars in the near-infrared to measure the relative iron and \mgii emission strengths. A detailed comparison of the resulting spectra with those of low-redshift quasars show essentially the same FeII/...
0109208v1
2002-03-29
The shape of the relativistic iron K-alpha line from MCG6--6-30-15 measured with the Chandra HETGS and RXTE
We confirm the detection of the relativistically broadened iron K-alpha emission at 6.4 keV with simultaneous Chandra HETGS and RXTE PCA observations. Heavily binned HETGS data show a disk line profile with parameters very similar to those previously seen by ASCA. We observe a resolved narrow component with a velocity ...
0203523v2
2002-06-07
X-ray spectral diagnostics of the immediate environment of GRB 991216
The recent report of iron line features in the afterglow of the gamma-ray burst (GRB) 991216 has important implications for the properties of the radiating material and hence the nature of the immediate burst environment. We argue that the putative strong Fe emission line can be attributed to the reflected emission fro...
0206116v1
2002-07-08
Sulphur and iron abundances in halo stars
From equivalent widths of the SI lines at 8694 A, Israelian & Rebolo (2001) and Takada-Hidai et al. (2002) have derived a surprisingly high sulphur-to-iron ratio ([S/Fe] = 0.5 to 0.7) in six halo stars with [Fe/H] ~ -2.0 suggesting perhaps that hypernovae made a significant contribution to the formation of elements in ...
0207163v1
2002-07-29
The iron Kalpha Compton Shoulder in transmitted and reflected spectra
We calculate the Equivalent Widht of the Core and the centroid energy and relative flux of the 1st order Compton Shoulder of the iron Kalpha emission line from neutral matter. The calculations are performed with Monte Carlo simulations. We explore a large range of column densities for both transmitted and reflected spe...
0207615v1
2003-01-03
Implementing TOPbase/Iron Project: Continuous Absorption from Fe II
We discuss implementation of TOPbase and Iron Project opacities for stellar spectral codes. We use a technique employed by Peach, where a Boltzmann-averaged cross section is calculated for selected temperatures, and the opacity obtained from double interpolation in temperature and wavelength. It is straightforward to i...
0301045v1
2003-01-14
Relics of subluminous supernovae in metal-poor stars
The unique elemental abundance pattern of the carbon-rich stars CS29498-043 and CS22949-037 is characterized by a large excess of magnesium and silicon in comparison with iron. This excess is investigated in the context of a supernova-induced star formation scenario, and it is concluded that these stars were born from ...
0301236v1