22 research outputs found
FUV and X-ray absorption in the Warm-Hot Intergalactic Medium
The Warm-Hot Intergalactic Medium (WHIM) arises from shock-heated gas
collapsing in large-scale filaments and probably harbours a substantial
fraction of the baryons in the local Universe. Absorption-line measurements in
the ultraviolet (UV) and in the X-ray band currently represent the best method
to study the WHIM at low redshifts. We here describe the physical properties of
the WHIM and the concepts behind WHIM absorption line measurements of H I and
high ions such as O VI, O VII, and O VIII in the far-ultraviolet and X-ray
band. We review results of recent WHIM absorption line studies carried out with
UV and X-ray satellites such as FUSE, HST, Chandra, and XMM-Newton and discuss
their implications for our knowledge of the WHIM.Comment: 26 pages, 9 figures, accepted for publication in Space Science
Reviews, special issue "Clusters of galaxies: beyond the thermal view",
Editor J.S. Kaastra, Chapter 3; work done by an international team at the
International Space Science Institute (ISSI), Bern, organised by J.S.
Kaastra, A.M. Bykov, S. Schindler & J.A.M. Bleeke
Influence of surface ordering on the wetting of structured liquids
The substrate is shown to induce substantial ordering in diblock copolymer
thin films above the bulk order-disorder transition (ODT) where,
thermodynamically, a phase mixed state is favored. Initially, uniform films
reorganize to form a hierarchy of transient surface patterns and stable film
thicknesses that depend on the initial film thickness and on the substrate.
Self-consistent field calculations of the free energy of the system for
different situations, depending on the relative tendency for the different
block components to be attracted to the substrate and/or free surface,
provide an explanation of the formation of the stable film thicknesses. A
continuum picture proposed earlier by Brochard et al. provides an
explanation of the wetting characteristics of this system. In some cases the
ordering destabilizes the film so that dewetting occurs (wetting
autophobicity), whereas in other cases the surface ordering results in a
kinetic stabilization of a film that would otherwise dewet