Modeling X-ray Line Shapes from Asphaltenes

The Chemical Nature of Oxidized Sulphur in Asphaltenes from X-Ray Absorption Spectroscopy

Modeling O-Star X-Ray Emission-Line Profiles

X-ray emission from hot (Oand B-type) stars is a long-standing astrophysical puzzle. High-resolution x-ray spectroscopy of hot stars resolves emission line profile shapes, offering direct insight into the dynamics and spatial distribution of the x-ray-emitting plasma. The O supergiant ζ Puppis shows broad, blueshifted, and asymmetric line profiles, generally consistent with the wind-shock pictu...

Modeling X-ray emission from stellar coronae

By extrapolating from observationally derived surface magnetograms of low-mass stars we construct models of their coronal magnetic fields and compare the 3D field geometry with axial multipoles. AB Dor, which has a radiative core, has a very complex field, whereas V374 Peg, which is completely convective, has a simple dipolar field. We calculate global X-ray emission measures assuming that the ...

Many-electron singularity in X-ray photoemission and X-ray line spectra from metals

It is pointed out that the spectra of x-ray induced fast photoelectrons from metal should have a characteristic skew line shape resulting from Kondo-like manyelectron interactions of the metallic conduction electrons with the accompanying deep hole in the final state. The same line shape should also occur for the discrete line spectra of x-rays emitted from metals. This mechanism could account ...

Weak Hard X-ray Emission from Broad Absorption Line Quasars: Evidence for Intrinsic X-ray Weakness

We report NuSTAR observations of a sample of six X-ray weak broad absorption line (BAL) quasars. These targets, at z = 0.148–1.223, are among the optically brightest and most luminous BAL quasars known at z< 1.3. However, their rest-frame ≈ 2 keV luminosities are 14 to > 330 times weaker than expected for typical quasars. Our results from a pilot NuSTAR study of two low-redshift BAL quasars, a ...