Analysis of broad-band X/γ-ray spectra of NGC 4151 shows that the data are well modelled with an intrinsic spectrum due to thermal Comptonization with temperature ∼ 50 keV and X-ray spectral index α ∼ 0.4– 0.7. The variable X-ray spectrum pivots at ∼ 100 keV, which is consistent with the observed approximatly constant γ-ray spectrum. The observed UV/X-ray correlation can be explained by two spe...

Copper vanadate nanostructures were prepared via ex-situ precipitation approach in presence of Schiff-base ligand (N,N׳ -buthylenebis(acetylacetone iminato)dianion = acacbn) as a new capping agent. The effect of different Cu sources and pH on the size, morphology and size distribution of copper vanadate nanostructures was investigated. The as-prepared products were characterized using X-ray dif...

We present the first measurements of the angular dependence of the betatron x-ray spectrum produced by electrons inside the cavity of a laser-wakefield accelerator. Electrons accelerated up to 300 MeV energies produce a beam of broadband, forward-directed betatron x-ray radiation extending up to 80 keV. The angular resolved spectrum from an image plate-based spectrometer with differential filte...

It has been proposed that RX J1914.4+2456 is a stellar binary system with an orbital period of 9.5 mins. As such it shares many similar properties with RX J0806.3+1527 (5.4 mins). However, while the X-ray spectrum of RX J0806.3+1527 can be modelled using a simple absorbed blackbody, the X-ray spectrum of RX J1914.4+2456 has proved difficult to fit using a physically plausible model. In this pap...

We present evidence, based on Chandra ACIS-S observations of the nearby spiral galaxy NGC 6946, that the extraodinary X-ray luminosity of the MF 16 supernova remnant actually arises in a black-hole X-ray binary. This conclusion is drawn from the point-like nature of the X-ray source, its X-ray spectrum closely resembling the spectrum of other ultraluminous X-ray sources thought to be black-hole...

We present ROSAT All-Sky Survey and ROSAT pointed observations (PSPC and HRI) of a complete sample of 113 bright soft X-ray AGN selected from the ROSAT Bright Source Catalog. We compare these observations in order to search for extreme cases of flux and spectral X-ray variability-X-ray transient AGN. Three definite transients and one transient candidate are found. The other sources show amplitu...

We report the discovery of a 200 mHz quasi-periodic oscillation (QPO) in the X-ray emission from a bright ultra-luminous X-ray source (ULX) Holmberg IX X-1 using a long XMM-Newton observation. The QPO has a centroid at νQPO = 202.5 +4.9 −3.8 mHz, a coherence Q ≡ νQPO/∆νFWHM ≈ 9.3 and an amplitude (rms) of 6% in the 0.2 − 10 keV band. This is only the second detection of a QPO from an ULX, after...

Context. In April 2013, the nearby TeV blazar, Mkn 421, showed one of the largest flares in X-rays in the past decade. Aims. We study all multiwavelength data available during MJD 56 392 to 56 403, with special emphasis on X-ray data to understand the underlying particle energy distribution. Methods. We studied the correlations between the UV and gamma-ray bands with the X-ray band using the z-...