Current Research Highlights

The groundbreaking detections of gravitational waves from merging pairs of black holes have left us with an intriguing question: how do black holes get close enough to merge? Scientists at MPA show that some of them may have started out as massive stars orbiting one another at extremely large separations — 1,000 to 10,000 times the distance between Earth and Sun. Once these stars end their lives and form black holes, the gravity of the entire galaxy in which they reside could slowly deform the shape of their orbit leading to a close encounter and merger of the black holes. more

Among many X-ray sources in our Galaxy, the one called SS 433 (as an entry number 433 in the catalog of Halpha emitters by Stephenson & Sanduleak 1977) is especially famous and peculiar.  It is likely powered by a black hole in a massive binary system. The accretion rate on this black hole from its companion star is hundreds of times higher than the critical value known as the Eddington limit (when the pressure of produced radiation becomes so great that it can eject matter and form powerful “winds” of the accretion disk). The new model discusses the impact of such winds on the surrounding interstellar medium. In particular, this wind can inflate the giant W50 nebula, encompassing SS 433 and spanning tens of parsecs in size. A similar situation may occur for rapidly growing massive black holes at the dawn of the Universe, galaxies with extreme nucleus activity and star formation rates during the “Cosmic Noon” (when the Universe was about 2-3 billion years old), or in the most extreme ultraluminous X-ray sources in normal star-forming galaxies today. more

With the recent advancements in the Lyman-alpha observations, it becomes more and more important to have theoretical models to help us decode the intricate Lyman-alpha spectral line. Scientists at MPA developed a theoretical approach to describe the escape of Lyman-alpha from scenarios where there is an empty hole to emulate the porous gas around galaxies. more

Can machine learning make new discoveries in astrophysics? An ‘explainable’ neural network is employed to get insights into the origin of dark matter halo density profiles. The network discovers that the shape of the profile in the halo outskirts is described by a single parameter related to the most recent accretion of mass. This is done without prior knowledge of the halo’s evolution history being provided during training.
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A careful analysis of the filaments in the cosmic large-scale structure has revealed interesting new findings about the evolution and complexities of the cosmic web. While some filaments show a significant evolution – depending on their cosmic environment – global filament properties are preserved, which could be used in future cosmological studies. The MPA team also developed a new method to allow for rigorous calibration of the filament catalogues.
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The distribution of galaxies on large, cosmological scales holds important clues on the nature of dark matter, the properties of dark energy and the origin of our Universe. Yet, optimally retrieving this information from observations is challenging. MPA researchers are developing a novel analysis approach, where they follow the evolution of cosmic structures through their entire formation history. Enabling a very detailed comparison between theoretical models and observational data, this approach will allow measuring key parameters of dark matter and dark energy very precisely. more

Traditional studies of the gas around galaxies rely in particular on absorption and emission features of neutral hydrogen, the simplest and most abundant element in the universe. MPA researchers have now investigated alternative tracers, in particular the resonance doublet of singly ionized magnesium and found that analyzing this emission can lead to significant advances in studying the circum-galactic medium. They showed the potential of the magnesium doublet as an alternative to Lyman-alpha emission through a new radiative transfer code and suggest that the magnesium doublet ratio could even be used as a tracer of the Lyman-continuum escape. more

Betelgeuse is a well-known red supergiant star in the constellation Orion. Recently it has gained a lot of attention, not only because variations in its brightness led  to speculations that  an explosion might be imminent, but also because observations indicated that it’s rotating much faster than expected. This latter interpretation is now put into question by an international team led by astronomers at Max Planck Institute for Astrophysics, who propose that Betelgeuse’s boiling surface can be mistaken for rotation even in the most advanced telescopes. Other astronomers are actively analyzing new observational data to test such hypotheses. more

In dense stellar environments, interactions between stars and stellar-mass black holes should occur frequently. Through hydrodynamical simulations, researchers at MPA have explored how stars are disrupted in such encounters, varying key parameters such as stellar and black hole masses, stellar age, and approach distance. The study quantifies the impact of these initial parameters on stellar remnants' masses, spins, and trajectories, offering insights into cluster dynamics and providing best-fit formulae for post-disruption parameters. more

High-resolution three-dimensional maps of the Milky Way have previously been limited to the immediate vicinity of the Sun. In a collaboration led by the Max Planck Institute for Astrophysics with researchers from Harvard, the Space Telescope Science Institute, and the University of Toronto, we were now able to build a high-resolution map of the Milky Way in 3D out to more than 4,000 light-years. The produced 3D map will be highly useful for a wide range of applications from star formation to cosmological foreground correction. more

Space is filled with gases of vastly different temperatures and it is important to understand how these interact. A group of scientists at MPA has now looked into the mixing of gases with and without magnetic fields. Surprisingly, they find that the outcome depends on whether turbulence is already present at the beginning. Without turbulence, magnetic fields can suppress the mixing by suppressing turbulence, while if the turbulence is already present, magnetic fields have a marginal effect. more

The first billion years saw the transformation of a cold neutral Universe to a hot and ionised one. This Epoch of Reionisation is thought to come about from stellar radiation from the first galaxies. Understanding the nature of the galaxies that drove reionisation remains a key question. Scientists at MPA have designed a novel suite of simulations to systematically understand how different modes of energy and mass injection from stars affect the first galaxies. According to these new models, subtle differences in the behaviour of stellar feedback drive profound differences in the morphologies of galaxies and the speed at which they ionise the universe. Combining these findings with the latest observations will help constrain feedback models in the first billion years of the Universe. more