One of the remaining challenges for accurate photon diagnostics at X-ray free-electron lasers (FELs) is the shot-to-shot, non-destructive, high-resolution characterization of the FEL pulse spectrum at photon energies between 2 keV and 4 keV, the so-called tender X-ray range. Here, a spectrometer setup is reported, based on the von Hamos geometry and using elastic scattering as a fingerprint of ...

We report for the first time on the rapid X-ray variability of the galactic bulge source and X-ray burster SLX 1735–269. The power spectrum as observed with the Rossi X-ray Timing Explorer is characterized by a strong band-limited noise component which is approximately flat below a 0.1–2.3 Hz break frequency; above this frequency the power spectrum declines as a power law of index 0.9. At the h...

We present almost-simultaneous detections of Cygnus X-1 in the radio and mm regimes, obtained during the low/hard X-ray state. The source displays a flat spectrum between 2 and 220 GHz, with a spectral index |α| ≤ 0.15(3σ). There is no evidence for either a lowor high-frequency cut-off, but in the mid-infrared (∼ 30μm) thermal emission from the OB-type companion star becomes dominant. The integ...

The terms X-ray absorption near edge structure (XANES) and extended X-ray absorption fine structure (EXAFS) refer, respectively, to the structure in the X-ray absorption spectrum at low and high energies relative to the absorption edge. Routine analysis of EXAFS experiments generally makes use of simplified models and several many-body parameters, e.g. mean free paths, many-body amplitude facto...

We present a study of the X-ray coronal emission from the active binary VY Ari, using data from both the Low Energy Concentrator Spectrometer (LECS) and the Medium Energy Concentrator Spectrometer (MECS) instruments onboard the X-ray satellite BeppoSAX. Using these instruments, the X-ray spectrum of VY Ari can be studied across two full decades of energy, from 0.1 to 10 keV. The spectrum is wel...

Preliminary analysis of the X-ray spectrum of NGC 1068 obtained by the RGS spectrometer on board XMM-Newton is presented. A physically consistent model is developed in order to quantitatively describe the reprocessing of the central AGN continuum source into the discrete X-ray emission observed in Seyfert 2 galaxies. All the important atomic processes are taken into account, including photoexci...