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2018-05-02
The Problem of the High Iron Abundance in Accretion Disks around Black Holes
In most accreting black-hole systems the copious X-rays commonly observed from the inner-most regions are accompanied by a reflection spectrum. The latter is the signature of energetic photons reprocessed by the optically thick material of an accretion disk. Given their abundance and fluorescence yield, the iron K-shel...
1805.00581v1
2018-10-25
Limits on stable iron in Type$\,$Ia supernovae from NIR spectroscopy
We obtained optical and near-infrared spectra of Type$\,$Ia supernovae (SNe$\,$Ia) at epochs ranging from 224 to 496 days after the explosion. The spectra show emission lines from forbidden transitions of singly ionised iron and cobalt atoms. We used non-local thermodynamic equilibrium (NLTE) modelling of the first and...
1810.10781v1
2019-02-06
Partial order induced superconductivity in $Fe^{2+}$ iron
In this letter, we address a novel mechanism for iron based superconductors. We study $F^{2+}$ state of iron with six 3d electrons. Five of them are localized with ferromagnetic order, while the sixth one is itinerant antiparallel with the localized ones. We consider spin-fermion model of 3d electrons and show that one...
1902.02290v2
2020-05-27
Prediction of exotic magnetic states in the alkali metal quasi-one-dimensional iron selenide compound Na$_2$FeSe$_2$
The magnetic and electronic phase diagram of a model for the quasi-one-dimensional alkali metal iron selenide compound Na$_2$FeSe$_2$ is presented. The novelty of this material is that the valence of iron is Fe$^{2+}$ contrary to most other iron-chain compounds with valence Fe$^{3+}$. Using first-principles techniques,...
2005.13132v1
2020-10-01
Molecular Dynamics Simulation for the Analysis of Mechanical Properties and Effect of Stone-Wales and BiVacancy Defect on Carbon Nanotube Reinforced Iron Composites
Carbon nanotube (CNT) reinforced metal matrix composites (MMCs) are gaining the attention of the researchers because of their demand in space and automobile industries for having low weight and high mechanical properties. Iron is the most used metal in all engineering fields. Therefore, reinforcing iron with CNT can re...
2010.00275v1
2021-01-19
Quantitative analysis of iron sand mineral content from the south coast of Cidaun, West Java using rietveld refinement method
Iron sand is one of the abundant natural resources in Indonesia, especially on the south coast of Cidaun; West Java which is the basic material for building and metal industry. Iron mineral content is generally metal oxide such as magnetite, hematite and silica/quartz. Sand with iron content used in this study is deriv...
2101.10442v1
2021-10-20
Manifestations of Spinodal Decomposition into Dilute Pd$_{1-x}$Fe$_{x}$ "Phases" in Iron-Implanted Palladium Films: FMR Study
Palladium-iron alloys produced by high-dose implantation of iron ions into epitaxial palladium films were investigated with the ferromagnetic resonance (FMR) and vibrating sample magnetometry (VSM) techniques. The samples reveal distinct multiple FMR responses depending on the dose of iron ion implantation. The post-im...
2110.10397v1
2021-11-02
Structure and motifs of iron oxides from 1 to 3 TPa
Iron oxides are fundamental components of planet-forming materials. Understanding the Fe-O system's behavior and properties under high pressure can help us identify many new phases and states possible in exoplanetary interiors, especially terrestrial ones. Using the adaptive genetic algorithm (AGA), we investigate the ...
2111.01305v2
2022-01-07
Online 3-Axis Magnetometer Hard-Iron and Soft-Iron Bias and Angular Velocity Sensor Bias Estimation Using Angular Velocity Sensors for Improved Dynamic Heading Accuracy
This article addresses the problem of dynamic on-line estimation and compensation of hard-iron and soft-iron biases of 3-axis magnetometers under dynamic motion in field robotics, utilizing only biased measurements from a 3-axis magnetometer and a 3-axis angular rate sensor. The proposed magnetometer and angular veloci...
2201.02449v1
2022-10-19
GRB 180325A: dust grain-size distribution and interstellar iron nanoparticles contribution
We modelled dust grain-size distributions for carbonaceous and silicates dust, as well as for free-flying iron nanoparticles in the environment of a $\gamma$-ray burst (GRB) afterglow, GRB 180325A. This GRB, at $z=2.2486$, has an unambiguous detection of the 2175 \r{A} extinction feature with $R_V=4.58$ and $A_V=1.58$....
2210.10423v1
2023-01-30
The Curie line in protoplanetary disks and the formation of Mercury-like planets
In laboratory experiments, we heated chondritic material up to 1400K in a hydrogen atmosphere. Moessbauer spectroscopy and magnetometry reveal that, at high temperatures, metallic iron forms from silicates. The transition temperature is about 1200K after 1 h of tempering, likely decreasing to about 1000K for longer tem...
2301.12910v1
2023-02-28
Correlating Chemical Reaction and Mass Transport in Hydrogen-based Direct Reduction of Iron Oxide
Steelmaking contributes 8% to the total CO2 emissions globally, primarily due to coal-based iron ore reduction. Clean hydrogen-based ironmaking has variable performance because the dominant gas-solid reduction mechanism is set by the defects and pores inside the mm-nm sized oxide particles that change significantly as ...
2302.14215v2
2023-04-26
The width-flux relation of the broad iron line during the state transition of the black hole X-ray binaries
The observation of varying broad iron lines during the state transition of the black hole X-ray binaries (BHXBs) have been accumulating.In this work, the relation between the normalized intensity and the width of iron lines is investigated, in order to understand better the variation of iron lines and possibly its conn...
2304.13358v1
2023-05-09
Reproduction Experiments of Radial Pyroxene Chondrules Using a Gas-jet Levitation System under Reduced Conditions
Reproduction experiments of radial pyroxene (RP) chondrules were carried out using an Ar-$\mathrm{H_2}$ or Ar gas-jet levitation system in a reducing atmosphere in order to simulate chondrule formation in the protoplanetary disk. The experiments reproduced RP-chondrule textures, consisting of sets of thin pyroxene crys...
2305.05787v4
2023-07-31
Trading oxygen for iron I: the [O/Fe] -- specific star formation rate relation of galaxies
Our current knowledge of star-forming metallicity relies primarily on gas-phase oxygen abundance measurements. This may not allow one to accurately describe differences in stellar evolution and feedback driven by variations in iron abundance. $\alpha$-elements (such as oxygen) and iron are produced by sources that oper...
2308.00023v1
2023-08-28
R-Matrix calculations for opacities.II. Photoionization and oscillator strengths of iron ions FeXVII, FeXVIII and FeXIX
Iron is the dominant heavy element that plays an important role in radiation transport in stellar interiors. Owing to its abundance and large number of bound levels and transitions, iron ions determine the opacity more than any other astrophysically abundant element. A few iron ions constitute the abundance and opacity...
2308.14854v1
2023-09-05
Calculated iron $L_{2,3}$ x-ray absorption and XMCD of spin-crossover Fe(phen)$_{2}$(NCS)$_{2}$ molecule adsorbed on Cu(001) surface
The PAW method has been used to compute the iron L$_{2,3}$ edges of x-ray absorption spectra (XAS) and x-ray magnetic circular dichroism (XMCD) of the spin-crossover Fe(phen)$_{2}$(NCS)$_{2}$ molecule when adsorbed on Cu(001) surface and in the gas phase, for both the high spin (HS) and low spin (LS) states. It is foun...
2309.02078v1
2024-01-29
Pulsed Iron line Emission from the First Galactic Ultraluminous X-ray Pulsar Swift J0243.6+6124
We report the phase-resolved spectral results of the first Galactic Pulsating Ultra-Luminous X-ray source (PULX) Swift J0243.6+6124, modeling at its 2017-2018 outburst peak using data collected by the Hard X-ray Modulation Telescope (Insight-HXMT). The broad energy coverage of Insight-HXMT allows us to obtain more accu...
2401.15992v1
1996-09-06
The Iron Discrepancy in Elliptical Galaxies after ASCA
We present estimates for the iron content of the stellar and diffused components of elliptical galaxies, as derived respectively from integrated optical spectra and from ASCA X-ray observations. A macroscopic discrepancy emerges between the expected iron abundances in the hot interstellar medium (ISM) and what is indic...
9609046v1
2002-08-22
How the BAL quasars are quiet
All properties of the quasars known by the author (quietness of the BAL quasars, Lyman forest, iron in the high-z quasars...) are explained supposing that the kernel of the quasar is surrounded by a halo containing an accretion disk and magnetic satellites (no dark matter or fast jet, no variation of the fine structure...
0208405v1
2003-10-23
The Iron Project and the RmaX Project
Ongoing activities under an international collaboration of atomic physicists and astrophysicists under the Iron Project and the RmaX Project, with applications to X-ray astronomy, are briefly described.
0310700v1
2004-12-14
Live Fe-60 in the Early Solar System
The latest finding by Hester et al. supports the view of ". . . iron cores of the inner planets, iron meteorites, and the core of the sun as likely condensation products from the supernova core." [Science 195, 209 (14 January 1977)]
0412349v2
2005-06-03
A Chandra HETGS Spectral Study of the Iron K Bandpass in MCG-6-30-15: A Narrow View of the Broad Iron Line
We present a high resolution X-ray spectrum of the iron K bandpass in MCG-6-30-15 based on a 522 ksec observation with Chandra's High Energy Transmission Grating Spectrometer. The Chandra spectrum is consistent with the presence of a relativistically broadened, highly redshifted iron K alpha emission line with a simila...
0506082v1
2006-10-13
Suzaku Observations of Iron Lines and Reflection in AGN
Initial results on the iron K-shell line and reflection component in several AGN observed as part of the Suzaku Guaranteed time program are reviewed. This paper discusses a small sample of Compton-thin Seyferts observed to date with Suzaku; namely MCG -5-23-16, MCG -6-30-15, NGC 4051, NGC 3516, NGC 2110, 3C 120 and NGC...
0610436v1
2006-11-28
Iron line and diffuse hard X-ray emission from the starburst galaxy M82
We examine the properties of the diffuse hard X-ray emission in the classic starburst galaxy M82. We use new Chandra ACIS-S observations in combination with reprocessed archival Chandra ACIS-I and XMM-Newton observations. We find E~6.7 keV Fe He-alpha emission is present in the central |r| < 200 pc, |z| < 100 pc of M82...
0611859v1
2006-12-08
Iron Air collision with high density QCD
The color glass condensate approach describes successfully heavy ion collisions at RHIC. We investigate Iron-air collisions within this approach and compare results to event generators commonly used in air shower simulations. We estimate uncertainties in the extrapolation to GZK energies and discuss implications for ai...
0612218v1
2004-09-03
Helicoidal ordering in iron perovskites
We consider magnetic ordering in materials with negative charge transfer energy, such as iron perovskite oxides. We show that for a large weight of oxygen holes in conduction bands, the double exchange mechanism favors a helicoidal rather than ferromagnetic spin ordering both in metals, e.g. SrFeO_3 and insulators with...
0409068v1
2009-09-01
Discovery of the Iron Isotopes
Twenty-eight iron isotopes have so far been observed; the discovery of these isotopes is discussed. For each isotope a brief summary of the first refereed publication, including the production and identification method, is presented.
0909.0091v1
2010-01-05
Response to I. I. Mazin's correspondence on "Electronic correlations in the iron pnictides"
We discuss the discrepancy between the measured optical Drude weight and band structure calculations in LaFePO and other iron-based superconductors. This discrepancy is mostly due to mass renormalization arising from electronic correlation effects.
1001.0643v1
2010-06-07
Screening of the Raman response in multiband superconductors -- application to iron-pnictides
We performed model calculations of Raman responses for multiband 2D superconductors. The multiband effects of screening in the A_{1g} symmetry channel were investigated analytically and numerically for a band structure model mimicing ARPES data on iron-pnictide materials. An acceptable agreement between our model calcu...
1006.1333v1
2010-10-13
Atomic structure and electronic properties of nanotubes of layered iron-based superconductors
The atomic models of nanotubes for layered FeSe, LiFeAs, SrFe2As2, and LnFeAsO - the parent phases of so-called 11, 111, 122, and 1111 groups of newly discovered family of iron-based high temperature superconductors are proposed. On example of SrFe2As2 the electronic properties of predicted nanotubes are examined and d...
1010.2624v1
2010-11-09
Iron lines in model disk spectra of galactic black hole binaries
We present angle-dependent, broad-band intensity spectra from accretion disks around black holes of 10 M$_\odot$. In our computations disks are assumed to be slim, which means that the radial advection is taken into account while computing effective temperature of the disk. We attempt to reconstruct continuum and line ...
1011.2061v1
2010-12-15
Reply to Comment on "Violation of Anderson's Theorem for the sign-reversing s-wave state of Iron-Pnictide Superconductors" [arXiv:1012.0414] by Y. Bang
We explain that the study of impurity effect in iron pnictides are correctly calculated based on the T-matrix approximation, contrary to the Comment by Bang. The replacement T with T-I proposed by Bang breaks the perturbation theory and is therefore erroneous.
1012.3307v1
2011-01-05
Pressure study of the new iron-based superconductor K0.8Fe2Se2
We investigated pressure effects on transition temperature (Tc) of the new iron-based superconductor K0.8Fe2Se2 using a BeCu/NiCrAl hybrid-type clamped piston-cylinder cell. The Tc(onset) was 33K at 0.85 GPa. With increasing pressure, Tc(onset) gradually increased and reached 36.6 K at 2.03 GPa.
1101.0896v1
2011-03-15
Dirac cone in iron-based high Tc superconductors
The band structure of iron-based superconductors gives rise to yet another scenario for the appearance of Dirac fermions. A viewpoint on "Observation of Dirac cone electronic dispersion in BaFe2As2" (Richard et.al., PRL 104, 137001 (2010)).
1103.2946v1
2012-02-10
A perspective of superconductivity as multiband phenomena: Cuprate, iron and aromatic systems
A theoretical overview of the classes of superconductors encompassing (a) high-Tc cuprate, (b) iron-based and (c) aromatic superconductors is given. Emphasis is put on the multiband natures of all the three classes, where the differences in the multiorbits and their manifestations in the electronic structures and pairi...
1202.2170v1
2012-05-05
The mechanism of anisotropic exchange interaction in superconducting iron arsenides
Using a combination of linear response theory and constrained orbital hybridization approach, we study the mechanism of magnetic exchange interaction of iron-based superconductor. We reproduce the observed highly anisotropic exchange interaction, and our constrain-orbital calculation unambiguously identifies that the a...
1205.1109v1
2013-12-18
Strongly magnetized iron white dwarfs and the total lepton number violation
The influence of a neutrinoless electron to positron conversion on a cooling of strongly magnetized iron white dwarfs is studied.
1312.5343v1
2014-06-30
Magnetic anisotropy in FeSb studied by 57Fe Mössbauer spectroscopy
The Fe(1+x)Sb compound has been synthesized close to stoichiometry with x = 0.023(8). The compound was investigated by 57Fe M\"ossbauer spectroscopy in the temperature range 4.2 - 300 K. The antiferromagnetic ordering temperature was found as 232 K i.e. much higher than for the less stoichiometric material. Regular iro...
1406.7767v2
2014-07-18
Iron-free detectors for future linear colliders
We continue consideration of Iron-free magnetic systems for possible application in detectors for high energy collider. In particular we suggest a new type of magnetic system with the multiple flux-return solenoids. This system allows reaching higher field level at IP compared with traditional ones.
1407.5056v1
2014-11-27
The critical relaxation of the model of iron-vanadium magnetic superlattice
The critical relaxation of iron-vanadium magnetic superlattice in case of the equality between interlayer and intralayer exchange interactions is investigated. The dynamic and static critical exponents of the model are calculated. A value of the critical temperature is evaluated.
1411.7505v1
2015-08-26
Nuclear Reactions For Nucleosynthesis Beyond Fe
Many more nuclear transitions have to be known in the determination of stellar reactivities for trans-iron nucleosynthesis than for reactions of light nuclei. This requires different theoretical and experimental approaches. Some of the issues specific for trans-iron nucleosynthesis are discussed.
1508.06569v1
2015-10-06
Local Stellar Kinematics from RAVE data - VI. Metallicity Gradients Based on the F-G Main-sequence Stars
We estimated iron and metallicity gradients in the radial and vertical directions with the F and G type dwarfs taken from the RAVE DR4 database. The sample defined by the constraints Zmax<=825 pc and ep<=0.10 consists of stars with metal abundances and space velocity components agreeable with the thin-disc stars. The r...
1510.01749v1
2016-04-23
M(H) dependence and size distribution of SPIONs measured by atomic magnetometry
We demonstrate that the quasistatic recording of the magnetic excitation function M(H) of superparamagnetic iron oxide magnetic nanoparticle (SPION) suspensions by an atomic magnetometer allows a precise determination of the sample's iron mass content mFe and the particle size distribution.
1604.06882v1
2016-06-03
Energy Losses of Magnetic Monopoles in Aluminum, Iron and Copper
The Energy Losses and Ranges of magnetic monopoles with magnetic charges $1g_{D}$, $2g_{D}$, $3g_{D}$, $6g_{D}$ and $9g_{D}$ in Aluminum, Iron and in Copper are computed, in the different regimes of velocities. The Restricted Energy Losses of monopoles with magnetic charges $1g_{D}$, $2g_{D}$ and $3g_{D}$ in Nuclear Tr...
1606.01220v1
2022-10-11
Oxygen and iron in interstellar dust: an X-ray investigation
Understanding the chemistry of the interstellar medium (ISM) is fundamental for the comprehension of the Galactic and stellar evolution. X-rays provide an excellent way to study the dust chemical composition and crystallinity along different sight-lines in the Galaxy. In this work we study the dust grain chemistry in t...
2210.05778v1
2023-07-05
Heterophased grain boundary-rich superparamagnetic Iron Oxides/carbon composite for Cationic and Anionic Dye Removal
Iron oxide-based nanostructures receive significant attention as an efficient adsorbent for organic dyes removal. The removal properties have strong dependency on the stoichiometry, phases, reactive edges, defect states etc present in the iron-oxides nanostructures. Herein, iron oxide/carbon composite with well-defined...
2307.02142v1
2007-07-15
Linear and nonlinear low frequency electrodynamics of the surface superconducting states in an yttrium hexaboride a single crystal
We report the low-frequency and tunneling studies of yttrium hexaboride single crystal. Ac susceptibility at frequencies 10 - 1500 Hz has been measured in parallel to the crystal surface DC felds, H0. We found that in the DC feld H0 > Hc2 DC magnetic moment completely disappears while the ac response exhibited the pres...
0707.2211v1
2013-09-18
The spin-state crossover and low-temperature magnetic state in yttrium doped Pr$_{0.7}$Ca$_{0.3}$CoO$_3$
The structural and magnetic properties of two mixed-valence cobaltites with formal population of 0.30 Co$^{4+}$ ions per f.u., (Pr$_{1-y}$Y$_{y}$)$_{0.7}$Ca$_{0.3}$CoO$_3$ ($y=0$ and 0.15), have been studied down to very low temperatures by means of the high-resolution neutron diffraction, SQUID magnetometry and heat c...
1309.4812v1
2016-08-31
Lattice instability and enhancement of superconductivity in YB$_6$
The superconducting and normal state characteristics of yttrium hexaboride (YB$_6$) have been investigated for the single crystals with a transition temperatures $T_c$ ranging between 6 K and 7.6 K. The extracted set of microscopic parameters [the coherence length $\xi$(0) $\sim$ 320$\div$340 ${\AA}$, the penetration d...
1608.08902v1
2019-08-05
Anomalous high-temperature superconductivity in YH$_6$
Pressure-stabilized hydrides are a new rapidly growing class of high-temperature superconductors which is believed to be described within the conventional phonon-mediated mechanism of coupling. Here we report the synthesis of yttrium hexahydride Im3m-YH$_6$ that demonstrates the superconducting transition with T$_c$ = ...
1908.01534v2
2020-02-23
Spectroscopy of YO from first principles
We report an ab initio study on the spectroscopy of the open-shell diatomic molecule yttrium oxide, YO. The study considers the six lowest doublet states, $X\,{}^{2}\Sigma^{+}$, $A\,{}^{2}\Pi$, $C\,{}^{2}\Pi$, $A'\,{}^{2}\Delta$, $B\,{}^{2}\Sigma^{+}$, $D\,{}^{2}\Sigma^{+}$ and a few higher-lying quartet states using h...
2002.09994v1
2020-07-30
Solid-state laser refrigeration of nanodiamond quantum sensors
The negatively-charged nitrogen vacancy (NV$^-$) centre in diamond is a remarkable optical quantum sensor for a range of applications including, nanoscale thermometry, magnetometry, single photon generation, quantum computing, and communication. However, to date the performance of these techniques using NV$^-$ centres ...
2007.15247v1
2021-12-14
Exploring yttrium doped C$_{24}$ fullerene as a high-capacity reversible hydrogen storage material: DFT investigations
By employing the state-of-the-art density functional theory, we report the hydrogen storage capability of yttrium decorated C$_{24}$ fullerene. Single Y atom attached on C$_{24}$ fullerene can reversibly adsorb a maximum number of 6 H$_2$ molecules with average adsorption energy -0.37 eV and average desorption temperat...
2112.07151v2
2023-09-04
NLTE analysis for Y I and Y II in atmospheres of F-G-K stars
The non-local thermodynamical equilibrium (NLTE) line formation of Y I and Y II is considered in 1D LTE model atmospheres of F-G-K-type stars. The model atom was constructed with the most up-to-date atomic data, including quantum cross sections and rate coefficients for transitions in inelastic collisions of Y I and Y ...
2309.01402v1
2023-10-13
Compound-tunable embedding potential method to model local electronic excitations on $f$-element ions in solids: Pilot relativistic coupled cluster study of Ce and Th impurities in yttrium orthophosphate, YPO$_4$
A method to simulate local properties and processes in crystals with impurities via constructing cluster models within the frame of the compound-tunable embedding potential (CTEP) and highly-accurate {\it ab initio} relativistic molecular-type electronic structure calculations is developed and applied to the Ce and Th-...
2310.09240v2
2017-12-19
Influence of gallium content on Ga3+ position and photo- and thermally stimulated luminescence in Ce3+ - doped multicomponent (Y,Lu,)3GaxAl5-xO12 garnets
Photoluminescence, thermally stimulated luminescence (TSL) and EPR characteristics of the Ce3+ doped single crystals of multicomponent Y1Lu2GaxAl5-xO12 and Lu3GaxAl5-xO12 garnets with different Ga contents (x = 0, 1, 2, 3, 4, 5) excited in the Ce3+ - related absorption bands are investigated in the 9 - 500 K temperatur...
1712.06925v1
2018-08-06
Lithium Metal Penetration Induced by Electrodeposition through Solid Electrolytes: Example in Single-Crystal Li6La3ZrTaO12 Garnet
Solid electrolytes are considered a potentially enabling component in rechargeable batteries that use lithium metal as the negative electrode, and thereby can safely access higher energy density than available with today's lithium ion batteries. To do so, the solid electrolyte must be able to suppress morphological ins...
1808.02105v1
2018-12-31
Oxygen-vacancy centers in Y3Al5O12 garnet crystals: electron paramagnetic resonance and dielectric spectroscopy study
F+ center, an electron trapped at oxygen vacancy (VO), was investigated in the oxygen deficient Y3Al5O12 (YAG) crystals by EPR. The measurements were performed at temperatures 5-450 K and frequencies 9.4-350 GHz with using both the continue wave and pulse EPR technique. The pulse electron-nuclear double resonance was a...
1812.11873v2
2022-01-23
H$_2$O and CO$_2$ Surface Contamination of the Lithium-Stuffed Garnet
Understanding the reactivity of ubiquitous molecules on complex oxides has broad impacts in energy applications and catalysis. The garnet-type Li$_7$La$_3$Zr$_2$O$_{12}$ is a promising solid-state electrolyte for lithium(Li)-ion batteries, and it readily reacts with H$_2$O and CO$_2$ when exposed to ambient air. Such r...
2201.09348v1
2023-03-03
Comparative study of magnetocaloric properties for Gd$^{3+}$ compounds with different frustrated lattice geometries
As materials with suppressed ordering temperatures and enhanced ground state entropies, frustrated magnetic oxides are ideal candidates for cryogenic magnetocaloric refrigeration. While previous materials design has focused on tuning the magnetic moments, their interactions, and density of moments on the lattice, there...
2303.01773v1
1995-10-04
X-ray reflection in Galactic Black Hole Candidates: smeared edge profiles and resonant Auger destruction
We consider the spectra of Thomson-thick, geometrically-thin accretion discs around Galactic black hole candidates in the reflection model and compute their iron K edges and iron K$\alpha$ lines. We compare the smeared iron K edge profiles that we compute with observation and find them to be a satisfactory description ...
9510022v1
1997-06-04
The Galaxy Cluster Luminosity-Temperature Relationship and Iron Abundances - A Measure of Formation History ?
Both the X-ray luminosity-temperature (L-T) relationship and the iron abundance distribution of galaxy clusters show intrinsic dispersion. Using a large set of galaxy clusters with measured iron abundances we find a correlation between abundance and the relative deviation of a cluster from the mean L-T relationship. We...
9706041v1
1997-11-28
ICM masses in nearby and distant clusters of galaxies
We compile X-ray data of clusters of galaxies at a wide range of redshift $z=0.0\sim1.0$ and compare X-ray luminosities, gas masses, iron abundances and iron masses of nearby clusters and those of distant clusters as a function of plasma temperature. All the date presented in this paper have been obtained only with \AS...
9711353v1
1999-06-16
Iron line in the afterglow: a key to the progenitor
The discovery of a powerful and transient iron line feature in the X-ray afterglow spectrum of GRB 970508 and GRB 970828, if confirmed, would be a major breakthrough for understanding the nature the progenitor of gamma-ray bursts. We show that a large mass of iron very close to the burster is necessary to produce the e...
9906268v1
1999-07-25
Constraints on Type Ia Supernova Models from X-ray Spectra of Galaxy Clusters
We present constraints on theoretical models of Type Ia supernovae using spatially resolved ASCA X-ray spectroscopy of three galaxy clusters: Abell 496, Abell 2199 and Abell 3571. All three clusters have central iron abundance enhancements; an ensemble of abundance ratios are used to show that most of the iron in the c...
9907343v1
1999-09-29
Mass-radius relations for white dwarf stars of different internal compositions
The purpose of this work is to present accurate and detailed mass-radius relations for white dwarf (WD) models with helium, carbon, oxygen, silicon and iron cores, by using a fully updated stellar evolutionary code. We considered masses from 0.15 to 0.5 Mo for the case of helium core, from 0.45 to 1.2 Mo for carbon, ox...
9909499v1
1999-10-08
Iron line reverberation mapping with Constellation-X
The broad X-ray iron line seen in the spectra of many AGN is thought to originate from the inner regions of the putative black hole accretion disk, and hence provides a rare probe of that central region. In principle, future high throughput X-ray spectrometers should be able to examine the temporal response of this flu...
9910168v1
2000-04-26
Broad iron lines in Active Galactic Nuclei
An intrinsically narrow line emitted by an accretion disk around a black hole appears broadened and skewed as a result of the Doppler effect and gravitational redshift. The fluorescent iron line in the X-ray band at 6.4-6.9keV is the strongest such line and is seen in the X-ray spectrum of many active galactic nuclei a...
0004366v1
2000-06-23
The iron abundance in hot central stars of planetary nebulae derived from IUE spectra
We present the first attempt to determine the iron abundance in hot central stars of planetary nebulae. We perform an analysis with fully metal-line blanketed NLTE model atmospheres for a sample of ten stars (T_eff >= 70.000 K) for which high-resolution UV spectra are available from the IUE archive. In all cases lines ...
0006338v1
2001-04-04
Iron line emission in X-ray afterglows
Recent observations of X-ray afterglows reveal the presence of a redshifted Kalpha iron line in emission in four bursts. In GRB 991216, the line was detected by the low energy grating of Chandra, which showed the line to be broad, with a full width of ~15,000 km/s. These observations indicate the presence of a >1 solar...
0104086v1
2001-08-31
The complex iron line of NGC 5506
The bright Narrow Emission Line Galaxy, NGC 5506, has been observed simultaneously by XMM-Newton and BeppoSAX. The iron line is complex, with at least two components: one narrow and corresponding to neutral iron, the second one broad and corresponding to ionized iron. The latter line is equally well fitted by a truly b...
0108508v1
2001-10-09
The intracluster iron distribution around 4C+55.16
We report on the metal distribution in the intracluster medium around the radio galaxy 4C+55.16 (z=0.24) observed with the Chandra X-ray Observatory. The radial metallicity profile shows a dramatic change at 10 arcsec (~50 kpc) in radius from half solar to twice solar at inner radii. Also found was a plume-like feature...
0110216v1
2002-05-19
Delayed Nickel Decay in Gamma Ray Bursts
Recently observed emission lines in the X-ray afterglow of gamma ray bursts suggest that iron group elements are either produced in the gamma ray burst, or are present nearby. If this material is the product of a thermonuclear burn, then such material would be expected to be rich in Nickel-56. If the nickel remains par...
0205321v1
2002-05-21
The complex iron line in NGC 7469 observed by BeppoSAX
In this letter we present analysis of BeppoSAX data from a long look at the Seyfert 1 galaxy NGC 7469. The presence of a soft excess below 0.8 keV is confirmed by our analysis and no warm absorber component is required to fit the spectrum. A complex iron emission line and the Compton reflection hump are clearly detecte...
0205347v1
2002-09-19
Cosmic Needles versus Cosmic Microwave Background Radiation
It has been suggested by a number of authors that the 2.7K cosmic microwave background (CMB) radiation might have arisen from the radiation from Population III objects thermalized by conducting cosmic graphite/iron needle-shaped dust. Due to lack of an accurate solution to the absorption properties of exceedingly elong...
0209386v1
2002-11-18
XMM-Newton Observations of AGN Iron Line Profiles
XMM-Newton observations of type I AGN are presented. The properties of the iron K emission line are reviewed, the majority of AGN observed by XMM-Newton show narrow, unresolved (by XMM) iron lines at 6.4 keV from cold matter that must originate far from the inner accretion disc, perhaps in the putative torus or outer b...
0211381v1
2003-07-08
The origin of the iron lines in NGC 7213
The analysis of a simultaneous XMM-Newton/BeppoSAX plus three previous BeppoSAX observations revealed that NGC 7213 is a rather peculiar Seyfert 1. No significant Compton reflection component was observed, while an iron line complex, best explained in terms of three narrow lines, is clearly apparent in the data. Due to...
0307143v1
2003-07-09
The lack of variability of the iron line in MCG-6-30-15: general relativistic effects
The spectrum and variability of the Seyfert galaxy MCG-6-30-15 can be decomposed into two apparently disconnected components: a highly variable power law and an almost constant component which contains a broad and strong iron line. We explore a possible explanation of the puzzling lack of variability of the iron line, ...
0307163v1
2003-11-13
The reprocessing features in the X-ray spectrum of the NELG MCG-5-23-16
We present results from the spectral analysis of the Seyfert 1.9 galaxy MCG-5-23-16, based on ASCA, BeppoSAX, Chandra and XMM-Newton observations. The spectrum of this object shows a complex iron Kalpha emission line, which is best modeled by a superposition of a narrow and a broad (possibly relativistic) iron line, to...
0311316v1
2003-11-27
The Iron Unresolved Transition Array in Active Galactic Nuclei
The unresolved transition array (UTA) of iron M-shell ions is a prominent absorption feature in the X-ray spectrum of many active galactic nuclei (AGNs). Modeling photoionized plasmas in attempt to match the observed silicon and oxygen lines fail to predict the level of ionization of iron as inferred by this feature. I...
0311604v1
2004-03-10
Handling of Atomic Data
State-of-the-art NLTE model-atmosphere codes have arrived at a high level of numerical sophistication and are now useful tools to analyze high-quality spectra from the infrared to the X-ray wavelength range. The capacity of current computers permit calculations which include line spectra from all elements from hydrogen...
0403239v1
2004-03-19
Extragalactic UHE proton spectrum and prediction for iron-nuclei flux at 10^8 - 10^9 GeV
We investigate the problem of transition from Galactic cosmic rays to extragalactic ultra high energy cosmic rays. Using the model for extragalactic ultra high energy cosmic rays and observed all-particle cosmic ray spectrum, we calculate the galactic spectrum of iron nuclei in the energy range $10^8 - 10^9$ GeV. The f...
0403477v2
2004-04-15
X-ray reprocessing in Seyfert Galaxies: simultaneous XMM-Newton/BeppoSAX observations
We selected a sample of eight bright unobscured (at least at the iron line energy) Seyfert Galaxies observed simultaneously by XMM-Newton and BeppoSAX, taking advantage of the complementary characteristics of the two missions. The main results of our analysis can be summarized as follows: narrow neutral iron lines are ...
0404308v1
2004-10-23
Why the Model of a Hydrogen-Filled Sun Is Obsolete
Isotope analyses on meteorites, planets, lunar samples, the solar wind, and solar flares show that heterogeneous debris of a supernova (SN) that exploded here 5 Gy ago formed the solar system. The Sun formed on the collapsed SN core. Iron meteorites and the iron cores of the terrestrial planets formed out of iron-rich ...
0410569v1
2004-11-22
The influence of chemical composition on the properties of Cepheid stars I - Period-Luminosity relation vs iron abundance
We have assessed the influence of the stellar iron content on the Cepheid Period-Luminosity (PL) relation by relating the V band residuals from the Freedman et al (2001) PL relation to [Fe/H] for 37 Galactic and Magellanic Clouds Cepheids. The iron abundances were measured from FEROS and UVES high-resolution and high-s...
0411594v2
2005-01-25
The Iron Line Background
We investigate the presence of iron line emission among faint X-ray sources identified in the 1Ms Chandra Deep Field South and in the 2Ms Chandra Deep Field North. Individual source spectra are stacked in seven redshift bins over the range z=0.5-4. We find that iron line emission is an ubiquitous property of X-ray sour...
0501542v1
2005-10-20
Truncated disc versus extremely broad iron line in XTE J1650-500
There is growing evidence from both spectral and timing properties that there is a truncated inner accretion disc in low mass accretion rate Galactic black hole systems. The detection of extremely smeared relativistic iron lines in some of these systems is the only current piece of evidence which conflicts with this ge...
0510614v2
2006-03-06
Relativistic Iron lines at high redshifts
The shape and the intensity of the 6.4 keV iron line bring unique information on the geometrical and physical properties of the supermassive black hole and the surrounding accreting gas at the very center of Active Galactic Nuclei. While there are convincing evidences of a relativistically broadened iron line in a few ...
0603139v1
2006-08-24
Non-LTE modeling of supernova-fallback disks
We present a first detailed spectrum synthesis calculation of a supernova-fallback disk composed of iron. We assume a geometrically thin disk with a radial structure described by the classical alpha-disk model. The disk is represented by concentric rings radiating as plane-parallel slabs. The vertical structure and emi...
0608529v1
2006-09-15
A Short Review of Relativistic Iron Lines from Stellar-Mass Black Holes
In this contribution, I briefly review recent progress in detecting and measuring the properties of relativistic iron lines observed in stellar-mass black hole systems, and the aspects of these lines that are most relevant to studies of similar lines in Seyfert-1 AGN. In particular, the lines observed in stellar-mass b...
0609447v1
2006-11-14
Chandra Detection of Fe XVII in Absorption: Iron Abundance in the Hot Gaseous Interstellar Medium
The iron depletion level and the gas-phase iron abundance in the hot ~10^6 K interstellar medium (ISM) is critical to the understanding of its energy balance as well as the thermal sputtering, cooling, and heating processes of dust grains. Here we report on the first detection of the Fe XVII absorption line at 15.02 A ...
0611446v2
2006-11-21
Discovery of Variable Iron Fluorescence from Reflection Nebulae in the Galactic Center
Based on three years of deep observations of the Galactic center with the Chandra X-ray Observatory, we report the discovery of changes in the intensities and morphologies of two hard X-ray nebulosities. The nebulosities are dominated by fluorescent iron emission, and are coincident with molecular clouds. The morpholog...
0611651v1
2007-01-17
Galactic Basins of Helium and Iron around the Knee Energy
The differential energy spectrum of cosmic rays exhibits a change of slope, called "knee" of the spectrum, around the nominal energy of 3 x 10^15 eV, and individual "knees" for single ions, at different energies. The present work reports a detailed account of the characteristics and the origin of the knees for Helium a...
0701498v1
1999-05-21
Structure and Dynamics of Liquid Iron under Earth's Core Conditions
First-principles molecular dynamics simulations based on density-functional theory and the projector augmented wave (PAW) technique have been used to study the structural and dynamical properties of liquid iron under Earth's core conditions. As evidence for the accuracy of the techniques, we present PAW results for a r...
9905319v1
2001-05-11
Magnetization Process of Nanoscale Iron Cluster
Low-temperature magnetization process of the nanoscale iron cluster in linearly sweeped fields is investigated by a numerical analysis of time-dependent Schr$\ddot{\rm o}$dinger equation and the quantum master equation. We introduce an effective basis method extracting important states, by which we can obtain the magne...
0105227v1
2001-11-26
Evidence of local magnetic order in hcp iron from Raman mode splitting
Experimental measurements of Raman spectra for hcp iron at high pressure show two modes over a considerable pressure range in contrast to the prediction of one doubly degenerate mode for the hcp lattice. We use density functional theory to investigate the influence of magnetic order on the Raman active modes of hcp iro...
0111487v1
2003-10-22
Unconventional superconductivity and normal state properties of epsilon-iron at high pressure
Following the discovery of superconductivity in epsilon-iron, subsequent experiments hinted at non-Fermi liquid behaviour of the normal phase and sensitive dependence of the superconducting state on disorder, both signatures of unconventional pairing. We report further resistive measurements under pressure of samples o...
0310519v1
2004-05-19
Dynamics of the magnetic and structural a -> e phase transition in Iron
We have studied the high-pressure iron bcc to hcp phase transition by simultaneous X-ray Magnetic Circular Dichroism (XMCD) and X-ray Absorption Spectroscopy (XAS) with an X-ray dispersive spectrometer. The combination of the two techniques allows us to obtain simultaneously information on both the structure and the ma...
0405439v4
2005-01-17
Electronic structure of nanoscale iron oxide particles measured by scanning tunneling and photoelectron spectroscopies
We have investigated the electronic structure of nano-sized iron oxide by scanning tunnelling microscopy (STM) and spectroscopy (STS) as well as by photoelectron spectroscopy. Nano particles were produced by thermal treatment of Ferritin molecules containing a self-assembled core of iron oxide. Depending on the thermal...
0501377v1