相关论文: disnht: modeling X-ray absorption from distributed…
We present a comprehensive study of interstellar X-ray extinction using the extensive Chandra supernova remnant archive and use our results to refine the empirical relation between the hydrogen column density and optical extinction. In our…
We present an improved model for the absorption of X-rays in the ISM intended for use with data from future X-ray missions with larger effective areas and increased energy resolution such as Chandra and XMM, in the energy range above 100eV.…
We present a detailed study of X-ray absorption in the local interstellar medium by analyzing the X-ray spectra of 24 galactic sources obtained with the {\it Chandra} High Energy Transmission Grating Spectrometer and the {\it XMM-Newton}…
We study the X-ray absorption of a complete sample of 99 bright Swift gamma-ray bursts. Over the last few years, a strong correlation between the intrinsic X-ray absorbing column density (N_H(z)) and the redshift was found. This absorption…
We model the absorption of X-rays by gas obscuring the source and photoionized by it. We consider a broad range of column densities, including both Thomson-thin and Thomson-thick media. For the Thomson thin regime, we derive a simple…
We present a three-dimensional map of the hydrogen density distribution in the Galactic interstellar medium. The hydrogen equivalent column densities were obtained from the Exploring the X-ray Transient and variable Sky project ({\sc…
We present an X-ray absorption model for the interstellar medium, to be referred to as ISMabs, that takes into account both neutral and ionized species of cosmically abundant elements, and includes the most accurate atomic data available.…
Interstellar extinction includes both absorption and scattering of photons from interstellar gas and dust grains, and it has the effect of altering a source's spectrum and its total observed intensity. However, while multiple absorption…
We review some of the main physical and statistical properties of the X-ray absorber in AGNs. In particular, we review the distribution of the absorbing column density inferred from X-ray observations of various AGN samples. We discuss the…
We have discovered a correlation between the X-ray absorbing column densities within Seyfert galaxies and the relative alignment between the central engines and their host galactic disks. This correlation carries several implications for…
Pulsars are remarkable objects that emit across the entire electromagnetic spectrum, providing a powerful probe of the interstellar medium. In this study, we investigate the relation between dispersion measure (DM) and X-ray absorption…
We studied the X-ray dust scattering halos around 17 bright X-ray point sources using {\it Chandra} data. We use an iterative method to resolve the halos at small scattering angles from the zeroth order data in CC-mode or the first order…
We remark on the utility of an observational relation between the absorption column density in excess of the Galactic absorption column density, $\Delta N_{\rm H} = N_{\rm H, fit} - N_{\rm H, gal}$, and redshift, z, determined from all 55…
Sub-millimetre dust emission is often used to derive the column density N of dense interstellar clouds. The observations consist of data at several wavelengths but of variable resolution. We examine two procedures that been proposed for the…
Current X-ray observatories make it possible to follow the evolution of transient and variable X-ray binaries across a broad range in luminosity and source behavior. In such studies, it can be unclear whether evolution in the low energy…
We have developed a new X-ray absorption model, called {\tt IONeq}, which computes the optical depth $\tau(E)$ simultaneously for ions of all abundant elements, assuming ionization equilibrium and taking into account turbulent broadening.…
Scattering and absorption of X-rays by interstellar dust is calculated for a model consisting of carbonaceous grains and amorphous silicate grains. The calculations employ realistic dielectric functions with structure near X-ray absorption…
We develop a mathematical model for adsorption based on averaging the flow around, and diffusion inside, adsorbent particles in a column. The model involves three coupled partial differential equations for the contaminant concentration both…
We study the dependence of column densities derived from absorption lines on the spatial distribution of the ions in an absorber. In particular, we investigate four varieties of coverage by the absorber of the background source: the…
We present a detailed study of the hydrogen density distribution in the local interstellar medium (ISM) using the X-ray absorption technique. Hydrogen column densities were precisely measured by fitting X-ray spectra from coronal sources…