Highly Resolved X-ray Spectra with Chandra: Dynamics of Neutral and   Ionized Matter
  The High Energy Transmission Grating Spectrometer (HETGS) onboard the Chandra X-ray Observatory has so far produced a large number of high resolution X-ray spectra with unprecedented spectroscopic details. Spectra from outflows in galactic and extragalactic X-ray sources indicate plasmas with a wide range of properties. Optically thick fluorescent matter and warm photoionized regions play as much a role as very hot regions where collisional ionization and scattering dominate the emission. Through the measurements of blue- and redshifts the complex dynamics of these plasmas is revealed. Quite intriguing in this respect is the case of X-ray absorption of neutral matter. In many cases spectral features are found to be of high complexity though the detection of edges from intermediate Z elements as well as absorption lines from monatomic species to molecular compounds. With the application of line diagnostic tools and more accurate atomic data bases we are now able to model the properties of these plasmas as well as measure line shifts and shapes to constrain their spatial distribution and dynamics. In various examples, i.e. plasmas from accretion disks, winds, stationary clouds as well as the ISM, the power of highly resolved X-ray spectra is demonstrated and the scientific capability of XEUS in this context is explored. 
Norbert S. Schulz