In this paper, we extend previous work on the absorption of high energy γ-rays in intergalactic space by calculating the absorption of 10 to 500 GeV γ-rays at high redshifts. This calculation requires the determination of the high-redshift evolution of the intergalactic starlight photon field, including its spectral energy distribution out to frequencies beyond the Lyman limit. To estimate this...

Knowledge of the monochromaticity of an x-ray source is increasingly important in fundamental experiments and critical applications. The bandwidth of an x-ray beam, selected from a synchrotron radiation spectrum for example, ultimately defines the limiting resolution of the synchrotron source. The development of x-ray technology through the use of characteristic line sources of fixed line shape...

We present the first grating-resolution X-ray spectra of the Seyfert 1 galaxy NGC 3783, obtained with the High Energy Transmission Grating Spectrometer on the Chandra X-Ray Observatory. These spectra reveal many narrow absorption lines from the H-like and He-like ions of O, Ne, Mg, Si, S, and Ar as well as Fe xvii-Fe xxi L-shell lines. We have also identified several weak emission lines, mainly...

We present the first grating-resolution X-ray spectra of the Seyfert 1 galaxy NGC 3783, obtained with the High Energy Transmission Grating Spectrometer on the Chandra X-ray Observatory. These spectra reveal many narrow absorption lines from the H-like and He-like ions of O, Ne, Mg, Si, S and Ar, as well as Fe XVII–Fe XXI L-shell lines. We have also identified several weak emission lines, mainly...

© Springer International Publishing Switzerland 2015 V. I. Ferronsky, Nuclear Geophysics, Springer Geophysics, DOI 10.1007/978-3-319-12451-3_2 Abstract Physical effects of a gamma-ray beam passing through matter as a basis for soil density determination is discussed. These effects for moderate-energy gamma rays are the photoelectric and Compton effects and production of electronpositron pairs i...

Prediction of the soft X-ray absorption along lines of sight through our Galaxy is crucial for understanding the spectra of extragalactic sources, but requires a good estimate of the foreground column density of photoelectric absorbing species. Assuming uniform elemental abundances this reduces to having a good estimate of the total hydrogen column density, NHtot = NH I + 2NH2 . The atomic comp...

We discuss the different physical processes that are important to understand the thermal X-ray emission and absorption spectra of the diffuse gas in clusters of galaxies and the warm-hot intergalactic medium. The ionisation balance, line and continuum emission and absorption properties are reviewed and several practical examples are given that illustrate the most important diagnostic features i...

We present the results of an analysis of data from XMM-Newton and CHANDRA observations of the high luminosity narrow-line quasar PG 1404+226. We confirm a strong soft X-ray excess in the X-ray spectrum and we find rapid variability (a factor of two in about 5000 s). When the X-ray spectrum is fit with a two component model which includes a power-law and a blackbody component, we find that low e...