scholarly journals A systematic study of soft X-ray pulse profiles of magnetars in quiescence

2019 ◽  
Vol 485 (3) ◽  
pp. 4274-4286 ◽  
Author(s):  
Chin-Ping Hu ◽  
C-Y Ng ◽  
Wynn C G Ho
Keyword(s):  
Magnetic Field ◽  
Systematic Study ◽  
High Surface ◽  
The Other ◽  
Quiescent State ◽  
High Luminosity ◽  
X Ray ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Fourier Harmonics

Abstract Magnetars are neutron stars with extremely high surface magnetic fields. They show diverse X-ray pulse profiles in the quiescent state. We perform a systematic Fourier analysis of their soft X-ray pulse profiles. We find that most magnetars have a single-peaked profile and hence have low amplitudes of the second Fourier harmonics (A2). On the other hand, the pulsed fraction (PF) spreads over a wide range. We compared the results with theoretical profiles assuming various surface hotspot asymmetries, viewing geometries, and beaming functions. We found that a single value of the intensity ratio r between two antipodal hotspots is unable to reproduce the observed distribution of A2 and PF for all magnetars. The inferred r is probably anticorrelated with the thermal luminosity, implying that high-luminosity magnetars tend to have two symmetric hotspots. Our results are consistent with theoretical predictions, for which the existence of an evolving toroidal magnetic field breaks the symmetry of the surface temperature.

scholarly journals NuSTAR and XMM–Newton observations of SXP 59 during its 2017 giant outburst

2019 ◽  
Vol 489 (1) ◽  
pp. 1000-1005
Author(s):  
Shan-Shan Weng ◽  
Ming-Yu Ge ◽  
Hai-Hui Zhao
Keyword(s):  
Magnetic Field ◽  
Pulse Shape ◽  
The Other ◽  
Limited Data ◽  
High Luminosity ◽  
Thermal Component ◽  
X Ray ◽  
Spectral Models ◽  
Dipole Magnetic Field ◽  
Energy Dependent

ABSTRACT The Be X-ray pulsar (BeXRP) SXP 59 underwent a giant outburst in 2017 with a peak X-ray luminosity of 1.1 × 1038 erg s−1. We report on the X-ray behaviour of SXP 59 with the XMM–Newton and NuSTAR observations collected at the outburst peak, decay, and the low luminosity states. The pulse profiles are energy dependent, the pulse fraction increases with the photon energy and saturates at 65 per cent above 10 keV. It is difficult to constrain the change in the geometry of emitting region with the limited data. Nevertheless, because the pulse shape generally has a double-peaked profile at high luminosity and a single peak profile at low luminosity, we prefer the scenario that the source transited from the super-critical state to the sub-critical regime. This result would further imply that the neutron star (NS) in SXP 59 has a typical magnetic field. We confirm that the soft excess revealed below 2 keV is dominated by a cool thermal component. On the other hand, the NuSTAR spectra can be described as a combination of the non-thermal component from the accretion column, a hot blackbody emission, and an iron emission line. The temperature of the hot thermal component decreases with time, while its size remains constant (R ∼ 0.6 km). The existence of the hot blackbody at high luminosity cannot be explained with the present accretion theories for BeXRPs. It means that either more sophisticated spectral models are required to describe the X-ray spectra of luminous BeXRPs, or there is non-dipole magnetic field close to the NS surface.

scholarly journals Determination of the Height of Hard X-Ray Sources in the Solar Atmosphere by Measurement of Photospheric Albedo Photons

1975 ◽  
Vol 68 ◽  
pp. 239-241
Author(s):  
John C. Brown ◽  
H. F. Van Beek
Keyword(s):  
Solar Atmosphere ◽  
The Other ◽  
X Ray ◽  
Theoretical Predictions ◽  
Source Models ◽  
The One

SummaryThe importance and difficulties of determining the height of hard X-ray sources in the solar atmosphere, in order to distinguish source models, have been discussed by Brown and McClymont (1974) and also in this Symposium (Brown, 1975; Datlowe, 1975). Theoretical predictions of this height, h, range between and 105 km above the photosphere for different models (Brown and McClymont, 1974; McClymont and Brown, 1974). Equally diverse values have been inferred from observations of synchronous chromospheric EUV bursts (Kane and Donnelly, 1971) on the one hand and from apparently behind-the-limb events (e.g. Datlowe, 1975) on the other.

scholarly journals Solar activity and solar oscillations

1997 ◽  
Vol 181 ◽  
pp. 277-285
Author(s):  
Y. Elsworth
Keyword(s):  
Magnetic Field ◽  
Solar Activity ◽  
Radio Emission ◽  
Surface Temperature ◽  
The Sun ◽  
Solar Oscillations ◽  
Thermal Component ◽  
X Ray ◽  
Convective Flows ◽  
Wide Range

Helioseismology provides us with the tools to probe solar activity. So that we can consider how the solar oscillations are influenced by that activity, we first consider the phenomena that we associate with the active Sun. The surface of the Sun is not quiet but shows evidence of convection on a wide range of scales from a few hundred kilometres through to several tens-of-thousands of kilometres. The surface temperature shows signs of the convection structures with the temperature in the bright granules being some 100 K to 200 K hotter than the surrounding dark lanes. Sunspots, which are regions of high magnetic field that suppress convective flows, are clearly visible to even quite crude observations. They are several tens-of-thousands of kilometres in diameter and about 2000 K cooler than their surroundings. Ultraviolet and X-ray pictures from satellites show that the higher layers of the solar atmosphere are very non-uniform with bright regions of high activity. Contemporaneous magnetograms show that these regions are associated with sunspots. Flares - regions of magnetic reconnections - are seen at all wavelengths from X-ray through the visible to radio. They are the non-thermal component of the radio emission of the Sun. There are many other indicators of activity on the Sun.

Glass-Coated Cu-Mn-Ga Microwires Produced by Taylor-Ulitovsky Technique

2009 ◽  
Vol 152-153 ◽  
pp. 79-84 ◽  
Author(s):  
Joan Josep Suñol ◽  
L. Escoda ◽  
C. García ◽  
V.M. Prida ◽  
Victor Vega ◽  
...  
Keyword(s):  
Magnetic Field ◽  
Solid Solution ◽  
Curie Temperature ◽  
Energy Dispersive Spectroscopy ◽  
Room Temperature ◽  
Alloy Composition ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Low Magnetic Field

Glass-coated Cu-Mn-Ga microwires were fabricated by Taylor-Ulitovsky technique. By means of energy dispersive spectroscopy microanalysis, an average alloy composition of Cu56Ga28Mn16 was determined. The temperature dependence of magnetization measured at a low magnetic field showed the coexistence of two ferromagnetic phases. The Curie temperature of one phase is 125 K and above room temperature for the other one. X-ray diffraction at room temperature and at 100 K reflects the presence of the same three crystalline phases corresponding to the cubic B2 Cu-Mn-Ga structure as a main phase and the minor phases of fcc Cu rich solid solution with Mn and Ga and the monoclinic CuO.

Transport Properties of Bi-related Nanowire Systems

2001 ◽  
Vol 635 ◽  
Author(s):  
Y. M. Lin ◽  
S. B. Cronin ◽  
J. Y. Ying ◽  
J. Heremans ◽  
M. S. Dresselhaus
Keyword(s):  
Electrical Transport ◽  
Lattice Structure ◽  
X Ray Diffraction ◽  
Localization Transition ◽  
X Ray ◽  
3D Localization ◽  
Wide Range ◽  
Theoretical Predictions ◽  
Alloy Nanowires ◽  
Magneto Resistance

AbstractWe present here an electrical transport property study of Te-doped Bi nanowires, and Bi1−xSbx alloy nanowires embedded in a dielectric matrix. The crystal structure of the nanowires were characterized by X-ray diffraction measurements, indicating that the nanowires possess the same lattice structure as bulk Bi in the presence of a small amount of Te or Sb atoms. The resistance measurements of 40-nm Te-doped Bi nanowires were performed over a wide range of temperature (2 K≤ T ≤ 300 K), and the results are consistent with theoretical predictions. The 1D-to-3D localization transition and the boundary scattering effect are both observed in magneto-resistance measurements of Bi1−xSbx alloy nanowires at low temperatures (T < 4 K).

Multitechnique problem solving using EDS/EPMA and surface analysis

1992 ◽  
Vol 50 (2) ◽  
pp. 1782-1783
Author(s):  
Steven J. Simko ◽  
Richard A. Waldo
Keyword(s):  
Thin Films ◽  
Electron Beam ◽  
Integrated Circuits ◽  
Photoelectron Spectroscopy ◽  
Electron Spectroscopy ◽  
High Surface ◽  
Primary Electron ◽  
Sampling Depth ◽  
X Ray ◽  
Wide Range

Thin films are used in a wide range of modern technologies. Examples include sensors, antiwear coatings, optical coatings, and integrated circuits. A variety of methods have evolved for characterizing thin films in the thickness range of 1 monolayer to several micrometers. Electron probe microanalysis (EPMA) or energy dispersive x-ray spectroscopy (EDS) are two methods for characterizing thicker films (>1 μm). In these techniques, the sampling depth depends on the penetration depth of the primary electron beam which can be controlled by changing the electron beam energy. Thin films can also be characterized using line scans on specimens prepared as polished cross-sections or after angle lapping. For extremely thin films (<3 nm), techniques with high surface sensitivity such as Auger electron spectroscopy (AES) and x-ray photoelectron spectroscopy (XPS) are commonly employed. Sampling depth depends on the attenuation length of the emitted photoelectrons or Auger electrons.Electron spectroscopy techniques are also used to characterize thicker films by adding a microsectioning method to the experiment, most commonly ion sputtering.

Alignment of Primary Phase of a Binary Alloy during Solidification

2007 ◽  
Vol 26-28 ◽  
pp. 563-565
Author(s):  
Kazuhiko Iwai ◽  
Manabu Usui ◽  
Shigeo Asai
Keyword(s):  
Magnetic Field ◽  
Magnetic Susceptibility ◽  
Diffraction Pattern ◽  
Primary Phase ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Specific Direction ◽  
Crystal Alignment ◽  
The Magnetic Field

A static magnetic field and an alternating current are imposed on a metallic alloy during solidification for a crystal alignment of the primary phase. A Sn-10%Pb is selected as a sample because its primary phase is expected to have an anisotropic nature in magnetic susceptibility. In the x-ray diffraction pattern of the sample solidified without the magnetic field, the first and second highest peaks are (101) and (211) planes. On the other hand, those solidified with the magnetic field are (200) and (220) planes which are magnetically preferred planes. That is, the primary phase crystals in the sample solidified with the magnetic field are aligned to the specific direction.

scholarly journals INTERACTION OF LANTHANE AND LUTETIUM AT TEMPERATURE 1500–1600°C

2020 ◽  
Vol 86 (3) ◽  
pp. 19-25
Author(s):  
Olga Chudinovych ◽  
Nataliya Zhdanyuk
Keyword(s):  
Systematic Study ◽  
Composition Range ◽  
Phase Relationship ◽  
X Ray Diffraction ◽  
X Ray ◽  
Heat Treated ◽  
Wide Range ◽  
Concentration Dependences ◽  
Perovskite Type ◽  
Perovskite Type Structure

Materials based on La2O3–Lu2O3 system are promising candidates for a wide range of applications, but the phase relationship has not been studied systematically previously. To address this challenge, the subsection of the phase diagram for 1500 and 1600 °C have been elucidated. The samples of different compositions have been prepared from nitrate acid solutions by evaporation, drying and heat treatment at 1100, 1500 and 1600 °C. The phase relations in the binary La2O3–Lu2O3 system at 1500 and 1600 °C were studied from the heat treated samples using X-ray diffraction analysis and scanning electron microscopy in the overall concentration range. The X–ray analysis of the samples was performed by powder method using DRON-3 at room temperature (CuKa radiation). It was established that in the binary La2O3–Lu2O3 system there exist fields of solid solutions based on hexagonal (A) modification of La2O3, cubic (C) modification of Lu2O3, and with perovskite–type structure of LaLuO3 (R) with rhombic distortions. The systematic study that covered whole composition range excluded formation of new phases. The systematic study that covered whole composition range excluded formation of new phases. The boundaries of mutual solubility and concentration dependences the lattice parameters for all phases have been determined. The solubility of Lu2O3 in the hexagonal А–lanthanum modification is ~ 9 mol. % at 1500 and 1600 °С. The solubility of La2O3 in the cubic C–Lu2O3 is ~ 4 mol. % at 1500 and 7 mol. % at 1600 °С.

X-Ray Studies in the Ti-O System*

1960 ◽  
Vol 4 ◽  
pp. 175-193 ◽  
Author(s):  
Norman F. H. Bright
Keyword(s):  
Atomic Ratio ◽  
The Other ◽  
X Ray Diffraction ◽  
X Ray ◽  
Monoclinic Form ◽  
Wide Range ◽  
Single Well ◽  
Crystalline Forms ◽  
Marked Tendency ◽  
Oxidation Behaviors

AbstractX-ray diffraction studies have revealed that a titanium oxide with an NaCl-type structure is stable over a wide range of nonstoichiometric compositions, both above and below the 1:1 Ti/O atomic ratio. Attempts to prepare a strictly stoichiometric TiO as a single phase have revealed a marked tendency for such a composition to disproportionate into two nonstoichiometric “TiO”-type structures of variable composition, whereas nonstoichiometric compositions can be readily prepared under similar conditions as single, well-crystallized phases.The oxide Ti3O5, which forms a constituent of the titanium-bearing slags produced in ilmenite smelting, has been prepared as a pure compound in two different crystalline forms, both monoclinic in structure, but one being very close to the orthorhombic pseudobrookite, Fe2O3 · TiO2, or ferrous dititanate, FeO · 2TiO2 structure. This “dititanate” form inverts to the other monoclinic form at high temperatures. Single crystals of the latter monoclinic form are readily made. The studies of the “dititanate” form have been restricted to powder diffraction work, since it inverts to the other form after melting. The two forms show different oxidation behaviors,

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