Current Research Highlights

Intermediate mass black holes (IMBH) should be linking observed stellar black holes and supermassive black holes, but their formation mechanisms are still debated. Young and dense massive star clusters are promising environments for the formation of such black holes through collisions. An international team lead by MPA researchers has presented novel realistic simulations of star clusters, where these missing links form by rapid collisions of stars and black holes. The study also predicts an IMBH formation channel by the merging of black holes in a mass regime, which is excluded by stellar evolution models. In this “mass gap” a black hole merger has indeed been observed recently by the LIGO/Virgo gravitational wave collaboration. more

Where are the baryons? This question naturally arises as the predicted abundance of baryons in the universe - the basic building blocks of all elements in the periodic table – do not agree with observations of the intergalactic medium. Locating the missing baryons will help us to not only better understand the formation and evolution of galaxies, but also to better constrain possible extensions of the current standard model of cosmology. MPA researchers have turned to a novel approach in modelling the galaxy distribution to optimize measurements of the kinematic Sunyaev-Zel'dovich effect, an emerging tool to probe the distribution of baryons in galaxy clusters. more

How can machine learning methods help us understand our tangled cosmic web? A new study presents a ‘deep learning’ framework to shed light onto the physics of the formation of dark matter halos. The results show that spherical averages over the initial conditions of the Universe carry the most relevant information about the final mass of halos. more

Radio telescopes observe the sky in a very indirect fashion. Sky images in the radio frequency range therefore have to be computed using sophisticated algorithms. Scientists at the MPI for Astrophysics have developed a series of improvements for these algorithms, which help to improve the telescopes' resolution considerably. more

Dark matter is the most abundant matter component in the universe. But while it influences all structure in the universe, its nature is still unknown. Among the many candidates is ultra-light dark matter, the lightest possible candidate for dark matter, which been receiving a lot of attention recently, as this might be probed by current and future experiments. MPA researchers have written a review on the current status of these models and their search for observational markers, introducing a division into three classes and showing how the rich phenomenology of this leading candidate for dark matter could help answer the question of what dark matter really is. more

Recently, astronomers discovered an extended glow of emission far beyond the stellar bodies of galaxies. While the emission is known to be associated with excited neutral hydrogen, the origin of this so called Lyman-alpha radiation is unknown. MPA researchers use new computational models to understand this emission, establishing that a large contribution is caused by light which originates from deep within galaxies but subsequently scatters at much larger distances. more

The Planck satellite mission to measure the cosmic microwave background radiation – the echo of the Big Bang – was completed in September 2020 with the publication of the final set of publications. In addition to groundbreaking insights into cosmology, the ESA mission also provided a large number of astrophysical results. A brief review. more

The origin of mysterious fast radio bursts (FRBs) has been debated since their discovery in 2007. A theory developed at Columbia University and MPA suggested that FRBs are emitted by blast waves from flaring magnetars -- neutron stars with ultrastrong magnetic fields. On 28 April 2020, an FRB was detected from SGR 1935+2154, a known magnetar in our Galaxy. A new numerical experiment demonstrates how perturbations can grow in a magnetar and launch a magnetic explosion – and a burst such as the observed one. more

When interstellar gas falls towards a supermassive black hole, it liberates vast amounts of energy - so vast as to be capable of ejecting much of a galaxy’s gaseous reservoir. Ultimately, supermassive black holes may thus deprive themselves of further fuel and bring about the end of their own growth and that of their host galaxies. A new model developed at MPA now makes it possible to simulate winds accelerated by accreting black holes in galaxy evolution simulations in a physically accurate and validated way. By blowing dense gas from the galactic nucleus, and by halting inward flows from the galactic halo, the winds play a vital role in shaping the evolution of the black hole host galaxy. more

Recently, in correspondence with the 10th birthday of LOFAR, a core group of researchers including MPA scientists published the most stringent upper limits on the reionization signal from the early Universe. These observations are able to exclude some reionization models and constrain the thermal and ionization state of the intergalactic medium when the Universe was still in its infancy. more

Extracting cosmological information from galaxy surveys is a difficult task – one to which MPA researchers are now one step closer. Using a theoretical framework known as effective field theory combined with a novel statistical approach, they were able to correctly recover the input cosmology based on a catalog of simplified simulated galaxies. more

About 10 billion years ago, a galaxy smashed into our cosmic home, the Milky Way, in a violent “merger” event that changed the way the Galaxy looks. Researchers from MPA together with international collaborators from the UK, Chile and Italy, have managed to piece together the impact of this event using the largest and most sophisticated simulations of the Milky Way to date. In particular, they found that the damage inflicted on the Galaxy in its youth is commensurate with a satellite that weights about a billion Suns. more

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