Why do galaxies in enormous galaxy clusters look different from normal, isolated galaxies? To answer this question, an international research team led by MPA has created the Hydrangea simulations, a suite of 24 high-resolution cosmological hydrodynamic simulations of galaxy clusters containing over 20,000 individual galaxies. These simulations provide astrophysicists with a powerful new tool to understand how galaxies formed and evolved in one of the most extreme environments of our Universe.
Researchers from the Max Planck Institute for Astrophysics and the University of Amsterdam just published the most precise analysis so far of the fluctuations in the gamma-ray background. They used more than six years of data gathered by the Fermi Large Area Telescope and found two different source classes contributing to the gamma-ray background. No traces of a contribution of dark matter particles were found in the analysis.
Complex predictions such as election forecasts or the weather reports often have to be simplified before communication. In astronomical data analysis, researchers are also confronted with the problem of simplifying probabilities. Two researchers at the MPA now show that there is only one mathematically correct way to measure how embarrassing a simplified prediction can be. According to this, the recipient of a prediction should be deprived of the smallest possible amount of information.
The diffuse gas around galaxies is hard to detect, but shows properties which are quite different to the star-forming gas inside a galaxy. Scientists at MPA have used observations from the recent MaNGA survey to study how the ionized gas changes with distance from the center of the galaxy. Adding spectra from multiple galaxies, their study shows that the brightness of the gas decreases, while its temperature increases the further the gas is located from the center of the galaxy.
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.
A pioneer in the development of electronic computing machines in Germany and one of the founders of gravitational wave astronomy is gone: on 4 January 2017, the astrophysicist Heinz Billing died at the age of 102. Billing was scientific member at the Max Planck Institute for Astrophysics in Garching from 1961 to '82.
Former MPA director Prof. Dr. Rudolf Kippenhahn has received the Honorary Membership of the German Astronomical Society. The President of the Astronomical Society, Prof. Dr. Matthias Steinmetz and Vice-President Prof. Dr. Joachim Wambsganß in Göttingen presented Kippenhahn with the official document just before christmas. The honorary membership was already announced at the AG anniversary 2016 in Bochum in September. With this award the society appreciates both Rudolf Kippenhahn's great research record and his outstanding contributions in the field of science communication.
This week, the European Research Council and MPA-postdoc Jérôme Guilet signed the agreement for an ERC Starting Grant. The project funded will research exploding stars from first principles, in particular magnetars as engines of hypernovae and gamma-ray bursts.