Related papers: Dynamic X-ray spectra of Chandra cataclysmic varia…
We present Chandra HETG spectra of seven cataclysmic variables. We find that they divide unambiguously into two distinct types. Spectra of the first type are remarkably well fit by a simple cooling flow model, which assumes only…
A technique of timescale analysis performed directly in the time domain has been developed recently. We have applied the technique to studying rapid variabilities of hard X-rays from neutron star and black hole binaries, gamma-ray bursts…
A personal selection of noteworthy X-ray results on CVs are presented, with emphasis on XMM-Newton and Chandra observations. Progressing roughly from broad-band view to narrow-band, high spectral resolution studies, I summarize: the energy…
We establish a theory for multivariate extreme value analysis of dynamical systems. Namely, we provide conditions adapted to the dynamical setting which enable the study of dependence between extreme values of the components of…
Principal Component Analysis (PCA) is applied to a variety of blazars to examine X-ray spectral variability. Data from nine different objects are analysed in two ways: long-term, which examines variability trends across years or decades,…
X-ray characterisation methods have undoubtedly enabled cutting-edge advances in all aspects of materials research. Despite the enormous breadth of information that can be extracted from these techniques, the challenge of radiation-induced…
X-ray spectroscopy is a powerful technique for the analysis of the energy distribution of X-rays from astrophysical sources. It allows for the study of the properties, composition, and physical processes taking place at the site of…
Stellar winds of massive stars are known to be driven by line absorption of UV photons, a mechanism which is prone to instabilities, causing the wind to be clumpy. The clumpy structure hampers wind mass-loss estimates, limiting our…
We review the X-ray spectral properties of magnetic cataclysmic binaries derived from observations obtained during the last decade with the large X-ray observatories XMM-Newton, Chandra and Suzaku. We focus on the signatures of the…
We calculate the spectrum of blast wave models of gamma-ray burst sources, for various assumptions about the magnetic field density and the relativistic particle acceleration efficiency. For a range of physically plausible models we find…
We study wave equations with energy dependent potentials. Simple analytical models are found useful to illustrate difficulties encountered with the calculation and interpretation of observables. A formal analysis shows under which…
Active galactic nuclei (AGNs) exhibit strong variability across the electromagnetic spectrum on a wide range of timescales, particularly in X-rays where fluctuations are both rapid and high amplitude. Power spectral density (PSD) analysis…
We study fractional variability as a function of energy from black-hole X-ray binaries on timescales from milliseconds to hundreds of seconds. We build a theoretical model of energy-dependent variability in which the X-ray energy spectrum…
The interpretation of Fourier spectra in the time domain is critically examined. Power density spectra defined and calculated in the time domain are compared with Fourier spectra in the frequency domain for three different types of…
The X-ray spectral curvature of blazars is traditionally explained by an empirical log-parabola function characterized by three parameters, namely the flux, curvature and spectral index at a given energy. Since their exact relationship with…
Cataclysmic Variables are a distinct class of interacting binaries, transferring mass from a donor star to a degenerate accretor, a white dwarf. We here review X-ray observations of these systems, with some emphasis on what has been…
Standard methods for describing the intensity distribution of mechanical and acoustic wave fields in the high frequency asymptotic limit are often based on flow transport equations. Common techniques are statistical energy analysis,…
Many X-ray observations of GigaHertz Peaked Spectrum and Compact Steep Spectrum sources have been made with Chandra X-ray Observatory and XMM-Newton Observatory over the last few years. The X-ray spectra contribute the important information…
We prove that a strong form of dynamical localization follows from a variable energy multi-scale analysis. This abstract result is applied to a number of models for wave propagation in disordered media.
We study samples of natural images for which a set of statistical characteristics is computed and scale-invariant properties of samples are demonstrated computationally. Computations of the power spectrum are carried out and a power-law…