Hard radiation of reological explosion

Abstract We present a detailed spectroscopic analysis of a galaxy at z ≃ 4.88 that is, by chance, magnified ∼30 × by gravitational lensing. Only three sources at z ≳ 5 are known with such high magnification. This particular source has been shown to exhibit widespread, high equivalent width ${\rm C\, {\small IV}}\, \lambda \, 1549$ emission, implying it is a unique example of a metal-poor galaxy with a hard radiation field, likely representing the galaxy population responsible for cosmic reionisation. Using UV nebular line ratio diagnostics, VLT/X-shooter observations rule out strong AGN activity, indicating a stellar origin of the hard radiation field instead. We present a new detection of ${[\rm Ne\, {\small III}]}\, \lambda \, 3870$ and use the [Ne iii]/[O ii] line ratio to constrain the ionisation parameter and gas-phase metallicity. Closely related to the commonly used [O iii]/[O ii] ratio, our [Ne iii]/[O ii] measurement shows this source is similar to local “Green Pea” galaxies and Lyman-continuum leakers. It furthermore suggests this galaxy is more metal poor than expected from the Fundamental Metallicity Relation, possibly as a consequence of excess gas accretion diluting the metallicity. Finally, we present the highest redshift detection of ${\rm Mg\, {\small II}}\, \lambda \, 2796$, observed at high equivalent width in emission, in contrast to more evolved systems predominantly exhibiting Mg ii absorption. Strong Mg ii emission has been observed in most z ∼ 0 Lyman-continuum leakers known and has recently been proposed as an indirect tracer of escaping ionising radiation. In conclusion, this strongly lensed galaxy, observed just 300 Myr after reionisation ends, enables testing of observational diagnostics proposed to constrain the physical properties of distant galaxies in the JWST/ELT era.

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Charge Density Studies of Transition Metal Compounds

X-Ray Charge Densities and Chemical Bonding ◽

10.1093/oso/9780195098235.003.0012 ◽

1997 ◽

Author(s):

Philip Coppens

Keyword(s):

Transition Metal ◽

Theoretical Calculations ◽

Transition Metal Compounds ◽

Metal Compounds ◽

Independent Evidence ◽

Hard Radiation ◽

Small Crystals ◽

Average Electron ◽

The One ◽

Van Vleck

The electron density in transition metal complexes is of unusual interest. The chemistry of transition metal compounds is of relevance for catalysis, for solid-state properties, and for a large number of key biological processes. The importance of transition-metal-based materials needs no further mention after the discovery of the high-Tc superconducting cuprates, the properties of which depend critically on the electronic structure in the CuO2 planes. The results of theoretical calculations of systems with a large number of electrons can be ambiguous because of the approximations involved and the frequent occurrence of low-lying excited states. The X-ray charge densities provide independent evidence from a technique with very different strengths and weaknesses, and thus can make significant contributions to our understanding of the properties of transition-metal-containing molecules and solids. In inorganic and organometallic solids, the average electron concentration tends to be high. This means that absorption and extinction effects can be severe, and that the use of hard radiation and very small crystals is frequently essential. Needless to say that the advent of synchrotron radiation has been most helpful in this respect. The weaker contribution of valence electrons compared with the scattering of first-row-atom-only solids implies that great care must be taken during data collection in order to obtain reliable information on the valence electron distribution. When the field exerted by the atomic environment is not spherically symmetric, as is the case in any crystal, the degeneracy of the d-electron orbitals is lifted. In the electrostatic crystal field theory, originally developed by Bethe (1929) and Van Vleck (1932), all interactions between the transition metal atom and its ligands are treated electrostatically, and covalent bonding is neglected. Since the ligands are almost always negatively charged, electrons in orbitals pointing towards the ligands are repelled more strongly, and the corresponding orbitals will be higher in energy. The discussion is the simplest for the one d-electron case, in which d-d electron repulsions are absent.

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X-ray and Gamma-ray Radiation from the Switched-off Radiopulsars

Symposium - International Astronomical Union ◽

10.1017/s0074180900034355 ◽

1983 ◽

Vol 101 ◽

pp. 505-507

Author(s):

A. I. Tsygan

Keyword(s):

Neutron Stars ◽

Magnetic Dipole ◽

Gamma Ray ◽

Neutral Hydrogen ◽

Dipole Radiation ◽

X Ray ◽

Electron Positron ◽

Hard Radiation ◽

Γ Ray ◽

Generate Electron

It is shown that pulsars that have ceased to generate electron-positron pairs (switched-off radiopulsars) may be the sources of X-ray and γ-ray radiation. The magnetic dipole radiation from these rotating neutron stars is transformed near the “light radius” into hard radiation by the plasma that is created due to ionization of interstellar neutral hydrogen.

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Chemodynamics of green pea galaxies – I. Outflows and turbulence driving the escape of ionizing photons and chemical enrichment

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa851 ◽

2020 ◽

Vol 494 (3) ◽

pp. 3541-3561 ◽

Cited By ~ 1

Author(s):

L Hogarth ◽

R Amorín ◽

J M Vílchez ◽

G F Hägele ◽

M Cardaci ◽

...

Keyword(s):

Emission Line ◽

Indirect Evidence ◽

Young Star ◽

High Dispersion ◽

H Ii Regions ◽

Ionized Gas ◽

Narrow Component ◽

Radiation Fields ◽

Hard Radiation ◽

Green Pea

ABSTRACT We investigate the ionized gas kinematics, physical properties, and chemical abundances of Sloan Digital Sky Survey J142947, a Green Pea galaxy at redshift z∼ 0.17 with strong, double-peak Ly α emission and indirect evidence of Lyman continuum (LyC) leakage. Using high-dispersion spectroscopy, we perform a multicomponent analysis of emission-line profiles. Our model consistently fits all lines as a narrow component with intrinsic velocity dispersion σ ∼ 40 km s−1, and two broader blue-shifted components with σ ∼ 90 and ∼ 250 km s−1. We find electron densities and temperatures, ionization conditions, and direct O/H and N/O abundances for each component. A highly ionized, metal-poor, young and compact starburst dominates narrow emission, showing evidence of hard radiation fields and elevated N/O. The blue-shifted broader components are consistent with highly turbulent, possibly clumpy ionized gas at the base of a strong photoionized outflow, which accounts for ≳50 per cent of the integrated emission-line fluxes. The outflow is dense and metal-enriched compared to the H ii regions, with expansion velocities larger than those obtained from UV interstellar absorption lines under standard assumptions. Some of these metals may be able to escape, with outflows loading factors comparable to those found in high-z galaxies of similar SFR/Area. Our findings depict a two-stage starburst picture; hard radiation fields from young star clusters illuminate a turbulent and clumpy ISM that has been eroded by SNe feedback. Whilst UV data suggest an extended Ly α halo with high average H i column density, LyC photons could only escape from SDSS J142947 through low H i density channels or filaments in the ISM approaching density-bounded conditions, traced by outflowing gas.

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Lightning current distribution and hard radiation in aircraft, measured in-flight

2017 International Symposium on Electromagnetic Compatibility - EMC EUROPE ◽

10.1109/emceurope.2017.8094765 ◽

2017 ◽

Author(s):

A.P.J. van Deursen ◽

P. Kochkin ◽

A.I. de Boer ◽

M. Bardet ◽

C. Allasia ◽

...

Keyword(s):

Current Distribution ◽

Lightning Current ◽

Hard Radiation

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X-Ray Fluorescence Analysis of Tungsten-Molybdenum Metals and Electrolytes

Advances in X-ray Analysis ◽

10.1154/s0376030800001270 ◽

1960 ◽

Vol 4 ◽

pp. 474-487

Author(s):

K. R. Stever ◽

J. L. Johnson ◽

H. H. Heady

Keyword(s):

Internal Standard ◽

Fluorescence Analysis ◽

Metal Powders ◽

Soft Or ◽

X Ray ◽

Molybdenum Metal ◽

Fused Salts ◽

Hard Radiation ◽

Impurity Elements

AbstractAn X-ray fluorescence method is presented for the analysis of tungsten-molybdenum solutions. Tungsten and molybdenum metal powders, produced by a fused-salt electrolysis procedure, are dissolved and analyzed for tungsten and molybdenum by using the W La1, Pt La1 intensity ratios. The platinum spectral line from the X-ray tube target serves as a self-internal standard. The sensitivity limit is about 0,05% and in the concentration range of 0.5 to 100%, the accuracy of analysis is within about 2% standard deviation. The technique is also applied to the analysis of tungsten and molybdenum in fused salts and to the determination of several other Impurity elements in these metals.A double detector modification for the General Electric X-ray unit is described. The detector consists of a double-window flow proportional counter tube backed up by a sealed krypton-filled counter tube. This allows counting of either soft or hard radiation at maximum efficiencies without the necessity of changing counter tubes. Advantages in specific applications are discussed.

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