The stellar discs of nearby spiral galaxies are generally not flat and often show waves and warps. A research team at MPA, together with external collaborators, have revisited question about their origins by analyzing new simulations of spiral galaxy formation. Their study shows that close encounters with satellite galaxies and more distant flybys of massive companions are the most common drivers. However, in some cases, bending patterns in discs can also be driven by the accretion of cold gas.
Observations are beginning to be sensitive enough to see the outskirts of galaxy clusters, where theory predicts interesting features in the dark matter and gas profiles: the so-called splashback and the accretion shock. Scientists at MPA use an analytical model to compute the locations of these features, and shed new light on the underlying physics.
From X-ray and SZ observations we know all major characteristics of the hot intracluster medium (ICM) filling the entire volume of galaxy clusters. However, several important properties are still poorly known, including thermal conduction in the ICM, mediated by electrons. Scientists at MPA have analysed the results of recent simulations including magnetic fields and found that the suppression of thermal conductivity by the so-called mirror instability is in fact rather modest, a factor of ~5 compared to unmagnetized plasma.
An international team of researchers have discovered an extremely rare “double source plane” gravitational lensing system, in which two distant galaxies are simultaneously lensed by a foreground galaxy, as part of the on-going Subaru Strategic Survey with Hyper Suprime-Cam. The team dubbed the system ‘Eye of Horus’ as the system resembles this ancient Egyptian symbol. Such a rare system is a unique probe of the fundamental physics of galaxies as well as cosmology.
Scientists are one step closer to answering the secrets of Dark Energy with the largest three-dimensional map of the universe so far: This map contains 1.2 million galaxies in a volume spanning 650 cubic billion light years. Hundreds of scientists from the Sloan Digital Sky Survey III (SDSS-III) – including researchers at MPA and MPE - used this map to make one of the most precise measurements yet of dark energy. They found excellent agreement with the standard cosmological model and confirmed that dark energy is highly consistent with a cosmological constant.
Using recent, extensive cosmological simulations, researchers at the MPA have shown that the expected signal from the Sunyaev-Zeldovich (SZ) effect of galaxy clusters on the Cosmic Microwave Background agrees remarkably well with observations by the Planck satellite. However, only a small fraction of this predicted signal is currently observable.
Dwarf galaxies can be a hundred times less massive than our Milky Way but they are the most numerous galaxies in the local Universe. Being very poor in heavy elements, they are thought to be local analogs of galaxies at high redshifts. An interesting puzzle of dwarf galaxies is that they form stars much less efficiently than typical spiral galaxies. Scientists at MPA have used high-resolution numerical simulations to resolve the multi-phase structure of their interstellar matter and thus investigate the origin of this deficiency in star formation.
Early July, the two junior MPA researchers Thomas Ertl and Chia-Yu Hu were awarded the Kippenhahn Prize 2015 for the two best scientific papers written by a student: Thomas Ertl for his publication “A two-parameter criterion for classifying the explodability of massive stars by the neutrino-driven mechanism”; Chia-Yu Hu for his paper “Star formation and molecular hydrogen in dwarf galaxies: a nonequilibrium view”.
A total of ten new members, including Fabian Schmidt of MPA, have been appointed to the Young Academy at the Berlin-Brandenburg Academy of Sciences (BBAW) and the German Academy of Sciences Leopoldina. On 11 June 2016, they were introduced in an official ceremony in Berlin, starting a new phase in the interdisciplinary work of the Young Academy.