Max Planck Institutes and Experts

After the first successful tests of the mid-infrared interferometric instrument MIDI at the ESO Very Large Telescope at the end of 2002, the phase of Science Demonstration followed in the year under report. MIDI fully met the high expectations and thus opened up a new field of astronomical observations: for the first time a resolution of one hundredth of an arc second can be achieved in the mid-infrared spectral range. Observations of circumstellar disks around young stars as well as of the dust ring in the center of an active galaxy demonstrate the enormous power of the instrument. MIDI was built by a consortium of German, Dutch, and French teams under the leadership of MPIA.

If the dark matter in the universe consists of weakly interacting elementary particles that can annihilate each other, it should be possible to detect their annihilation radiation directly. High-resolution cosmological simulations of the distribution of dark matter in the Milky Way can be used to make detailed predictions for the expected annihilation radiation from the galactic center and the satellite galaxies of the Milky Way. If the dark matter particles are neutralinos, these predictions imply favourable detection possibilities for next generation gamma ray telescopes.

Scientists at the Max-Planck-Institute for Astrophysics in Garching and the University of Chicago have substantiated an explanation for the high space velocities of observed pulsars. Their computer models confirm the likely connection with asymmetries during supernova explosions.

The two NASA rovers "Spirit" and "Opportunity" are currently successfully exploring their landing sites Gusev crater and Meridiani Planum on Mars. On board are two Alpha-Particle-X-ray-Spectrometers (APXS), which determine in-situ the chemical and mineralogical composition of rocks and soils. The chemistry of the analyzed surfaces clearly provides evidence for a water-rich past on planet Mars. The volcanic rocks at Gusev crater are covered by a rind and are penetrated by veins that are enriched in elements, e.g., sulfur, chlorine and bromine, which occur as anions in water. The chemistry of the old rocks at the Columbia Hills is altered to such an extent that their indigenous composition is difficult to deduce. The Meridiani Planum landing site exhibits bedrocks which consist of sulfates of up to 40 percent by weight. They were possibly deposited under conditions similar to those encountered presently in desert areas of the Earth.

In future mechanical and electronic devices, nanometer scale transport of material, energy and information will rely on novel physical principles. While the role of quantum effects will increase, dissipative processes causing unwanted heating will be reduced as much as possible. We study one particular transport mechanism, the so-called ratchet effect, in the limit of vanishing dissipation. For that purpose an analysis of the complex phase-space structure of Hamiltonian systems is necessary, in which regular and chaotic dynamics typically coexist.