X-ray Morphology Research Articles

THE HARD X-RAY VIEW OF THE YOUNG SUPERNOVA REMNANT G1.9+0.3

NuSTAR observed G1.9+0.3, the youngest known supernova remnant in the Milky Way, for 350 ks and detected emission up to $\sim$30 keV. The remnant's X-ray morphology does not change significantly across the energy range from 3 to 20 keV. A combined fit between NuSTAR and CHANDRA shows that the spectrum steepens with energy. The spectral shape can be well fitted with synchrotron emission from a power-law electron energy distribution with an exponential cutoff with no additional features. It can also be described by a purely phenomenological model such as a broken power-law or a power-law with an exponential cutoff, though these descriptions lack physical motivation. Using a fixed radio flux at 1 GHz of 1.17 Jy for the synchrotron model, we get a column density of N$_{\rm H}$ = $(7.23\pm0.07) \times 10^{22}$ cm$^{-2}$, a spectral index of $\alpha=0.633\pm0.003$, and a roll-off frequency of $\nu_{\rm rolloff}=(3.07\pm0.18) \times 10^{17}$ Hz. This can be explained by particle acceleration, to a maximum energy set by the finite remnant age, in a magnetic field of about 10 $\mu$G, for which our roll-off implies a maximum energy of about 100 TeV for both electrons and ions. Much higher magnetic-field strengths would produce an electron spectrum that was cut off by radiative losses, giving a much higher roll-off frequency that is independent of magnetic-field strength. In this case, ions could be accelerated to much higher energies. A search for $^{44}$Ti emission in the 67.9 keV line results in an upper limit of $1.5 \times 10^{-5}$ $\,\mathrm{ph}\,\mathrm{cm}^{-2}\,\mathrm{s}^{-1}$ assuming a line width of 4.0 keV (1 sigma).

Synthesis and identification of nanoparticles cobalt (II) bromide by ball mill method

Synthesis, identification and thermal behavior studies of nanoparticles cobalt (II) bromide has been studied in this research. Cobalt (II) bromide was synthesized by planetary high-energy ball mill. The general formula of this compound is CoBr2.6H2O. The synthesized nanoparticles were characterized by Fourier transform infrared spectroscopy and also Size and structure of synthesized nanoparticles were studied by analyzing X-ray diffraction and morphology of surface and structure of synthesized nanoparticles were studied by scanning electron microscopy. This compound has many applications in mineral synthesis as a catalyst. The nanoparticles of CoBr2.6H2O synthesized with smaller size of 35 nm, and its SEM images show that the morphology of particles surface is as like as layer. Also, the thermal behavior of these nanoparticles is considered by using of DTA /TGA thermal analysis.

Effect of Silicon Oxide Size and Reducing Environment on the Photocatalytic Capability of Poly(Vinyl Alcohol)/Chitosan/Silicon Oxide Beads

The present work assess the capability of silicon oxide (SiO2) nanoparticle and microparticle incorporated in poly (vinyl alcohol)/chitosan/silicon oxide (PVA/CS/SiO2) beads to reduce chromium (Cr) ions of Cr (VI) to Cr (III). PVA/CS/(nanoand micro)-SiO2 beads were prepared through a simple drop wise method. The elemental analysis of prepared photocatalytic beads were confirmed by scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) and morphology of PVA/CS/SiO2 beads before and after Cr ions reduction were observed with SEM. The reduction of chromium (Cr (VI)) ions by both of PVA/CS/(nanoand micro)-SiO2) beads, as evaluated by the reduction duration taken were studied by photocatalytic process in which factors of SiO2 powders size and pH of reducing environment were varied. Photocatalytic studies revealed better performance of PVA/CS/nanoSiO2 beads in compared to PVA/CS/micro-SiO2 beads in Cr (VI) to Cr (III) ions reduction. Reduction Cr (VI) to Cr (III) ions by PVA/CS/nanoSiO2 beads occurred in 30 minutes and 50 minutes by PVA/CS/micro-SiO2. Moreover, both PVA/CS/(nanoand micro)-SiO2 showed excellent reduction of Cr (VI) ions at lower pH environment. It is thus concluded that both of PVA/CS/(nanoand micro)-SiO2 beads are capable for chromium reduction in highly acidic environment in which PVA/CS/nanoSiO2 beads showed better performance.

THE MUSIC OF CLASH: PREDICTIONS ON THE CONCENTRATION-MASS RELATION

We present the results of a numerical study based on the analysis of the MUSIC-2 simulations, aimed at estimating the expected concentration-mass relation for the CLASH cluster sample. We study nearly 1400 halos simulated at high spatial and mass resolution, which were projected along many lines-of-sight each. We study the shape of both their density and surface-density profiles and fit them with a variety of radial functions, including the Navarro-Frenk-White, the generalised Navarro-Frenk-White, and the Einasto density profiles. We derive concentrations and masses from these fits and investigate their distributions as a function of redshift and halo relaxation. We use the X-ray image simulator X-MAS to produce simulated Chandra observations of the halos and we use them to identify objects resembling the X-ray morphologies and masses of the clusters in the CLASH X-ray selected sample. We also derive a concentration-mass relation for strong-lensing clusters. We find that the sample of simulated halos which resemble the X-ray morphology of the CLASH clusters is composed mainly by relaxed halos, but it also contains a significant fraction of un-relaxed systems. For such a sample we measure an average 2D concentration which is ~11% higher than found for the full sample of simulated halos. After accounting for projection and selection effects, the average NFW concentrations of CLASH clusters are expected to be intermediate between those predicted in 3D for relaxed and super-relaxed halos. Matching the simulations to the individual CLASH clusters on the basis of the X-ray morphology, we expect that the NFW concentrations recovered from the lensing analysis of the CLASH clusters are in the range [3-6], with an average value of 3.87 and a standard deviation of 0.61. Simulated halos with X-ray morphologies similar to those of the CLASH clusters are affected by a modest orientation bias.

On the diffuse X-ray emission from the Wolf–Rayet bubble NGC 2359

A recent XMM-Newton observation (Zhekov 2014) has revealed diffuse X-ray emission inside the nebula NGC 2359 around the Wolf-Rayet star WR 7. Taking advantage of an improved point-source rejection and background subtraction, and a detailed comparison of optical and X-ray morphology, we have reanalyzed these X-ray observations. Our analysis reveals diffuse X-ray emission from a blowout and the presence of emission at energies from 1.0 to 2.0 keV. The X-ray emission from NGC 2359 can be described by an optically-thin plasma emission model, but contrary to previous analysis, we find that the chemical abundances of this plasma are similar to those of the optical nebula, with no magnesium enhancement, and that two components at temperatures T_1=2x10^6 K and T_2=5.7x10^7 K are required. The estimated X-ray luminosity in the 0.3 - 2.0 keV energy range is L_X=2x10^33 erg s^-1. The averaged rms electron density of the X-ray-emitting gas (n_e \lesssim 0.6 cm^-3) reinforces the idea of mixing of material from the outer nebula into the hot bubble.

HFPK 334: AN UNUSUAL SUPERNOVA REMNANT IN THE SMALL MAGELLANIC CLOUD

We present new Australia Telescope Compact Array (ATCA) radio-continuum and XMM-Newton/Chandra X-ray Observatory (CXO) observations of the unusual supernova remnant HFPK 334 in the Small Magellanic Cloud (SMC). The remnant follows a shell type morphology in the radio-continuum and has a size of $\sim$20~pc at the SMC distance. The X-ray morphology is similar, however, we detect a prominent point source close to the center of the SNR exhibiting a spectrum with a best fit powerlaw with a photon index of $\Gamma = 2.7 \pm 0.5$. This central point source is most likely a background object and cannot be directly associated with the remnant. The high temperature, nonequilibrium conditions in the diffuse region suggest that this gas has been recently shocked and point toward a younger SNR with an age of $\lesssim 1800$ years. With an average radio spectral index of $\alpha=-0.59\pm0.09$ we find that an equipartition magnetic field for the remnant is $\sim$90~$\mu$G, a value typical of younger SNRs in low-density environments. Also, we report detection of scattered radio polarisation across the remnant at 20~cm, with a peak fractional polarisation level of 25$\pm$5\%.

A mid-infrared view of the inner parsecs of the Seyfert galaxy Mrk 1066 using CanariCam/GTC

We present mid-infrared (MIR) imaging and spectroscopic data of the Seyfert 2 galaxy Mrk 1066 obtained with CanariCam (CC) on the 10.4 m Gran Telescopio CANARIAS (GTC). The galaxy was observed in imaging mode with an angular resolution of 0.24 arcsec (54 pc) in the Si-2 filter (8.7 micron). The image reveals a series of star-forming knots within the central ~400 pc, after subtracting the dominant active galactic nucleus (AGN) component. We also subtracted this AGN unresolved component from the 8-13 micron spectra of the knots and the nucleus, and measured equivalent widths (EWs) of the 11.3 micron Polycyclic Aromatic Hydrocarbon (PAH) feature which are typical of pure starburst galaxies. This EW is larger in the nucleus than in the knots, confirming that, at least in the case of Mrk 1066, the AGN dilutes, rather than destroys, the molecules responsible for the 11.3 micron PAH emission. By comparing the nuclear GTC/CC spectrum with the Spitzer/IRS spectrum of the galaxy, we find that the AGN component that dominates the continuum emission at wavelengths below 15 micron on scales of ~60 pc (90-100%) decreases to 35-50% when the emission of the central ~830 pc is considered. On the other hand, the AGN contribution dominates the 15-25 micron emission (75%) on the scales probed by Spitzer/IRS. We find a good match between the MIR morphology of Mrk 1066 and the extended Pab, Brg and [O III] emission. This coincidence implies that the 8.7 micron emission is probing star formation, dust in the narrow-line region, and the oval structure previously detected in the near-infrared. On the other hand, the Chandra soft X-ray morphology does not match any of the previous, contrary to what it is generally assumed for Seyfert galaxies.

Energy Dissipation Mechanisms in Polycrystalline Superconductor Y3Ba5Cu8O y

The magnet-resistivity measurements of the Y-based Y3Ba5Cu8O18−x superconductor under different magnetic fields ranging from 0 to 200 mT have been carried out to understand the dissipation mechanisms in the resistive transition. Samples were synthesized in air by solid-state reaction method. Three models are employed to investigate the broadening of the resistive transition. The Ambegaokar–Halperin phase slip (AH), thermally activated flux creep (TAFC) models for granular superconductors, and Kosterlitz–Thouless (KT) model describing the vortex–antivortex unbinding for 2D. Phase analysis by X-ray diffraction (XRD) and morphology examination by scanning electron microscopy (SEM) were carried out. The AH and TAFC models cannot explain the whole of the broadening of resistive transition; a small temperature range is not described by these two models. Furthermore, our experimental data shows a good agreement with the KT model over the entire transition range justifying the picture of vortex–antivortex unbinding.

Synthesis and characterization of different MnO2 morphologies for lithium-air batteries

Manganese dioxide (MnO2) was synthesized in the forms of nanorods, nanoparticles, and mesoporous structures and the characteristics of these materials were investigated. Crystallinities were studied by x-ray diffraction and morphologies by scanning and transmission electron microscopy. Average pore sizes and specific surface areas were analyzed using the Barret-Joyner-Halenda and Brunauer-Emmett-Teller methods, respectively. Samples were also studied by cyclic voltammetry using 1M aqueous KOH solution saturated with either O2 or N2 as electrolytes to investigate their ORR (oxygen reduction reaction) and OER (oxygen evolution reaction) activities. Of the samples produced, mesoporous MnO2 exhibited the highest ORR and OER catalytic activities. Mesoporous MnO2 supported on a gas diffusion layer was also used as a catalyst on the air electrode (cathode) of a lithium-air battery in organic electrolyte. The charge-discharge behavior of mesoporous MnO2 was investigated at a current density 0.2 mAcm−2 in a pure oxygen environment. Mesoporous MnO2 electrodes showed stable cycleability up to 65 cycles at a cell capacity of 700 mAhg−1.

Optimization of ion-atomic beam source for deposition of GaN ultrathin films.

We describe the optimization and application of an ion-atomic beam source for ion-beam-assisted deposition of ultrathin films in ultrahigh vacuum. The device combines an effusion cell and electron-impact ion beam source to produce ultra-low energy (20-200 eV) ion beams and thermal atomic beams simultaneously. The source was equipped with a focusing system of electrostatic electrodes increasing the maximum nitrogen ion current density in the beam of a diameter of ≈15 mm by one order of magnitude (j ≈ 1000 nA/cm(2)). Hence, a successful growth of GaN ultrathin films on Si(111) 7 × 7 substrate surfaces at reasonable times and temperatures significantly lower (RT, 300 °C) than in conventional metalorganic chemical vapor deposition technologies (≈1000 °C) was achieved. The chemical composition of these films was characterized in situ by X-ray Photoelectron Spectroscopy and morphology ex situ using Scanning Electron Microscopy. It has been shown that the morphology of GaN layers strongly depends on the relative Ga-N bond concentration in the layers.

Discovery of impurities existing state in carbide slag by chemical dissociation

The existing states of impurities in carbide slag were investigated which can be a good guide for impurity removal by physical methods. The calcium phase and the impurities wrap each other made it hard to research impurities. Therefore an acid chemical dissociation method was firstly proposed via plotting Eh–pH-diagram of the Ca(OH)2, CaCO3, MgSiO3, Al2SiO5, Fe3O4 and H+ system. The optimum dissociation condition (pH=4.0) was deduced from Eh–pH-diagram and verified by X-ray diffraction, X-ray fluorescence spectrum and morphology analysis. Morphological and elemental chemical analyses of the dissociated residues revealed the existence of Si in the form of SiO2. Fe and C existed as isolated particles of Fe3O4 and carbon respectively. Al and Mg were existed in the form of silicates such as Al2SiO5 and MgSiO3. Si, Al and Mg always appeared together in the carbide slag, providing a possibility for their integral removal.

A 3D numerical model for Kepler's supernova remnant

We present new 3D numerical simulations for Kepler's supernova remnant. In this work we revisit the possibility that the asymmetric shape of the remnant in X-rays is the product of a Type Ia supernova explosion which occurs inside the wind bubble previously created by an AGB companion star. Due to the large peculiar velocity of the system, the interaction of the strong AGB wind with the interstellar medium results in a bow shock structure. In this new model we propose that the AGB wind is anisotropic, with properties such as mass-loss rate and density having a latitude dependence, and that the orientation of the polar axis of the AGB star is not aligned with the direction of motion. The ejecta from the Type Ia supernova explosion is modelled using a power-law density profile, and we let the remnant evolve for 400 yr. We computed synthetic X-ray maps from the numerical results. We find that the estimated size and peculiar X-ray morphology of Kepler's supernova remnant are well reproduced by considering an AGB mass-loss rate of 10−5 M⊙ yr−1, a wind terminal velocity of 10 km s−1, an ambient medium density of 10−3 cm−3 and an explosion energy of 7 × 1050 erg. The obtained total X-ray luminosity of the remnant in this model reaches 6 × 1050 erg, which is within a factor of 2 of the observed value, and the time evolution of the luminosity shows a rate of decrease in recent decades of ∼2.4 per cent yr−1 that is consistent with the observations.

Synthesis of ZSM-12 (MTW) with different Al-source: Towards understanding the effects of crystallization parameters

The effect of synthesis parameters on morphology of ZSM-12 (MTW) zeolite with tetra ethyl ammonium bromide (TEABr) as an organic-structure directing agent was investigated systematically. Aluminum sulfate octahydrate (Al2(SO4)3·18H2O) was used as an aluminum (Al) source. The Si/Al ratio was varied from 40 to 180 and alkalinity ratio (NaOH/Si) was set between 0.132 and 0.160. Effects of crystallization temperature and time were studied. The contribution of the aging period on the final morphology of ZSM-12 was investigated in the range of 1.5–6h. Phase identification of as-synthesized ZSM-12 was confirmed by X-ray diffraction and morphology of crystals was studied by electron microscopy. The alkalinity was one of the most substantial factors that induced the formation of ZSM-5 (MFI) nuclei as a competing phase. Pure ZSM-12 was obtained with Si/Al of 80 at 145°C. Different agglomeration shapes of ZSM-12 were observed by changing Si/Al ratio. Prolonged aging time up to 6h induced the formation of ZSM-5 nuclei.

Multiwavelength investigations of co-evolution of bright cluster galaxies and their host clusters

We report a systematic multiwavelength investigation of environments of the brightest cluster galaxies (BCGs), using the X-ray data from the Chandra archive, and optical images taken with 34 × 27 arcmin2 field-of-view Subaru Suprime-Cam. Our goal is to help understand the relationship between the BCGs and their host clusters, and between the BCGs and other galaxies, to eventually address a question of the formation and co-evolution of BCGs and the clusters. Our results include the following. (1) Morphological variety of BCGs, or the second or the third brightest galaxy (BCG2, BCG3), is comparable to that of other bright red sequence galaxies, suggesting that we have a continuous variation of morphology between BCGs, BCG2, and BCG3, rather than a sharp separation between the BCG and the rest of the bright galaxies. (2) The offset of the BCG position relative to the cluster centre is correlated to the degree of concentration of cluster X-ray morphology (Spearman ρ = −0.79), consistent with an interpretation that BCGs tend to be off-centred inside dynamically unsettled clusters. (3) Morphologically disturbed clusters tend to harbour the brighter BCGs, implying that the ‘early collapse’ may not be the only major mechanism to control the BCG formation and evolution.

Microwave Synthesis of Thin Film Absorber Layer Nanopowders of Copper-Indium-Gallium-(di) Selenide and Copper-Zinc-Tin-Sulfide

Microwave irradiation is a fast, reliable and efficient technique for thermally driven chemical reactions used to produce various in-organic nano-powders. This paper reviews the microwave synthesis method for the preparation of size and composition defined nanopowders of copper-indium-gallium-(di)selenide (CIGS) and copper-zinc-tin-sulfide (CZTS) applicable for absorber layers in thin film solar cells. For CIGS synthesis, precursor mixtures consisting of metal acetylacetonates and selenium powder in oleylamine and for CZTS synthesis, metal chlorides and thiourea in ammonium hydroxide and deionized water were heated in microwave at 180-220°C for 20-60 minutes respectively. The resultant nanopowder was characterized and optimized for particle size by dynamic light scattering, phase by X-ray diffraction, morphology and elemental distribution by scanning electron microscopy and band-gap by UV-Vis-NIR spectroscopy. CIGS and CZTS inks, suitable for spin coating and ink-jet printing were prepared and thin films were deposited and characterized. Keywords: Absorber layer, copper-indium-gallium-(di)selenide (CIGS), copper-zinc-tin-sulfide (CZTS), CIGS and CZTS inks, microwave irradiation, nano powder, non-vacuum deposition, sputter target, thin film solar cells, vaccum deposition.

THE X-RAY PROPERTIES OF FIVE GALACTIC SUPERNOVA REMNANTS DETECTED BY THESPITZERGLIMPSE SURVEY

(Abbreviated) We present a study of the X-ray properties of five Galactic supernova remnants (SNRs) -- Kes 17 (G304.6$+$0.1), G311.5$-$0.3, G346.6$-$0.2, CTB 37A (G348.5$+$0.1) and G348.5$-$0.0 -- that were detected in the infrared by Reach et al. (2006) in an analysis of data from the Galactic Legacy Infrared Mid-Plane Survey Extraordinaire (GLIMPSE) that was conducted by the Spitzer Space Telescope. We present and analyze archival ASCA observations of Kes 17, G311.5$-$0.3 and G346.6$-$0.2, archival XMM-Newton observations of Kes 17, CTB 37A and G348.5$-$0.0 and an archival Chandra observation of CTB 37A. All of the SNRs are clearly detected in the X-ray possibly except for G348.5$-$0.0. Our study reveals that the four detected SNRs all feature center-filled X-ray morphologies and that the observed emission from these sources is thermal in all cases. We argue that these SNRs should be classified as mixed-morphology SNRs (MM SNRs): our study strengthens the correlation between MM SNRs and SNRs interacting with molecular clouds and suggests that the origin of mixed-morphology SNRs may be due to the interactions between these SNRs and adjacent clouds. Our ASCA analysis of G311.5$-$0.3 reveals for the first time X-ray emission from this SNR: the X-ray emission is center-filled within the radio and infrared shells and thermal in nature ($kT$ $\sim$ 0.98 keV), thus motivating its classification as an MM SNR. We find considerable spectral variations in the properties associated with the plasmas of the other X-ray-detected SNRs, such as a possible overabundance of magnesium in the plasma of Kes 17. Finally, we also estimate such properties as electron density $n$$_e$, radiative age $t$$_{rad}$ and swept-up mass $M$$_X$ for each of the four X-ray-detected SNRs.

On the magnetohydrodynamic modelling of the Crab nebula radio emission

In recent years, it has become a well-established paradigm that many aspects of the physics of Pulsar Wind Nebulae (PWNe) can be fully accounted for within a relativistic MHD description. Numerical simulations have proven extremely successful in reproducing the X-ray morphology of the Crab Nebula, down to very fine detail. Radio emission, instead, is currently one of the most obscure aspects of the physics of these objects, and one that holds important information about pulsar properties and their role as antimatter factories. Here we address the question of radio emission morphology and integrated spectrum from the Crab Nebula, by using for the first time an axisymmetric dynamical model with parameters chosen to best reproduce its X-ray morphology. Based on our findings we discuss constraints on the origin of the radio emitting particles.

Modelling of the radio emission from the Vela supernova remnant

Supernova remnants (SNRs) are widely considered to be sites of Galactic cosmic ray (CR) acceleration. Vela is one of the nearest Galactic composite SNRs to Earth accompanied by the Vela pulsar and its pulsar wind nebula (PWN) Vela X. The Vela SNR is one of the most studied remnants and it benefits from precise estimates of various physical parameters such as distance and age. Therefore, it is a perfect object for a detailed study of physical processes in SNRs. The Vela SNR expands into the highly inhomogeneous cloudy interstellar medium (ISM) and its dynamics is determined by the heating and evaporation of ISM clouds. It features an asymmetrical X-ray morphology which is explained by the expansion into two media with different densities. This could occur if the progenitor of the Vela SNR exploded close to the edge of the stellar wind bubble of the nearby Wolf-Rayet star $\gamma^2$Velorum and hence one part of the remnant expands into the bubble. The interaction of the ejecta and the main shock of the remnant with ISM clouds causes formation of secondary shocks at which additional particle acceleration takes place. This may lead to the close to uniform distribution of relativistic particles inside the remnant. We calculate the synchrotron radio emission within the framework of the new hydrodynamical model which assumes the supernova explosion at the edge of the stellar wind bubble. The simulated radio emission agrees well with both the total radio flux from the remnant and the complicated radio morphology of the source.

Hollow Bessel-like beam as an optical guide for a stream of microscopic particles

Current aerosol sample injection methods for coherent x-ray morphology suffer from excessive sample consumption due to the dispersion of the aerosol. To remedy this we propose here a high aspect ratio optical funnel by using a hollow Bessel-like beam with variable divergence, which may reduce sample consumption significantly. We present estimated optical forces exerted on the particles in the transverse plane, depending on various experimental conditions. We show that light pressure imposed by a funnel formed with 4.2 W continuous wave laser is sufficient to divert a stream of 2 µm polystyrene particles travelling ~50 m/s by ~1.5 × 10(-3) rad.

SUPERNOVA REMNANT KES 17: AN EFFICIENT COSMIC RAY ACCELERATOR INSIDE A MOLECULAR CLOUD

Supernova remnant Kes 17 (SNR G304.6+0.1) is one of a few but growing number of remnants detected across the electromagnetic spectrum. In this paper, we analyze recent radio, X-ray, and gamma-ray observations of this object, determining that efficient cosmic ray acceleration is required to explain its broadband non-thermal spectrum. These observations also suggest that Kes 17 is expanding inside a molecular cloud, though our determination of its age depends on whether thermal conduction or clump evaporation is primarily responsible for its center-filled thermal X-ray morphology. Evidence for efficient cosmic ray acceleration in Kes 17 supports recent theoretical work that the strong magnetic field, turbulence, and clumpy nature of molecular clouds enhances cosmic ray production in supernova remnants. While additional observations are needed to confirm this interpretation, further study of Kes 17 is important for understanding how cosmic rays are accelerated in supernova remnants.