Frontiers Of Space And Ground Based Astronomy

Author: Willem Wamsteker
Publisher: Springer Science & Business Media
ISBN: 9401107947
Format: PDF, Mobi
Download Now
ROSAT Observations G. HASINGER Max-Planck-Institut flir extraterrestrische Physik, D-85740 Garching, Germany Abstract. This review describes the most recent advances in the study of the extragalactic soft X-ray background and what we can learn about its constituents. The deepest pointed observations with the ROSAT PSPC are discussed. The logN-logS relation is presented, which reaches to the faintest X-ray fluxes and to the highest AGN surface densities ever achieved. The N(>S) relation shows a 2 density in excess of 400 deg- at the faintest fluxes and a flattening below the Einstein Deep Survey limit. About 60% of the extragalactic background has been resolved in the deepest field. Detailed source spectra and first optical and radio identifications will be discussed. The results are put into perspective of the higher energy X -ray background. Key words: X-rays, background radiations, active galactic nuclei. 1. Introduction The extragalactic X-ray background (XRB), discovered about 30 years ago, has been studied extensively with many X-ray experiments, in particular with the satel lites HEAO I and II (see ego Boldt 1987) and with ROSAT (e. g. Hasinger et aI. , 1993). Figure 1 shows a compilation of some of the most recent spectral measure ments for the X-ray background. Over the energy range from 3 to about 100 keY its spectrum can be well approximated by an optically thin thermal bremsstrahlung model with kT ~ 40 keY, while at lower X-ray energies a steepening into a new component has been observed observed (e. g.

Extreme Ultraviolet Astronomy

Author: Martin A. Barstow
Publisher: Cambridge University Press
ISBN: 9781139435123
Format: PDF, Docs
Download Now
This text describes the development of astronomy in the Extreme Ultraviolet (EUV) wavelength range, from the first rocket-based experiments in the late 1960s through to later satellite missions. Discussions of the results from important space projects are followed by an analysis of the contributions made by EUV astronomy to the study of specific groups of astronomical objects. Within this framework, the book provides detailed material on the tools of EUV astronomy, dealing with the instrumentation, observational techniques, and modelling tools for the interpretation of data. Prospects for future EUV missions are discussed, and a catalogue of the known EUV sources is included. This book will be of great value to graduate students and researchers. It gives a complete overview of Extreme Ultraviolet astronomy.