The centre of the Milky Way, Sgr A* experienced short but intense flares over the past few hundred years. The time delay caused by light propagation from Sgr A* to the surrounding clouds and then to us, allows MPA scientists to study Sgr A*’s past activity. At the same time, flares serve as an extremely powerful probe of molecular gas properties. In particular, the full 3D structure of molecular clouds and their density distribution on small scales can be reconstructed.
Using three-dimensional general relativistic magnetohydrodynamic simulations, scientists at the MPA have studied thick accretion disks orbiting around black holes. They find that weak magnetic fields can suppress the development of large-scale over-densities in the accretion flow. The onset of magnetic turbulence reshapes the disk's structure and could even quench the gravitational-wave signal produced without magnetic fields.
The magnetic fields of the Milky Way cause electrons with nearly the speed of light to rotate and to emit radio waves. As consequence, this radiation should also "rotate" slightly, it is circularly polarized. Researchers at the Max Planck Institute for Astrophysics and colleagues have now predicted some properties of this polarization and created a "wanted poster" to allow targeted searches.
Stars exploding as supernovae are the main sources of heavy chemical elements in the Universe. Using elaborate computer simulations, a team of researchers from the MPA and RIKEN in Japan were able to explain the recently measured spatial distributions of radioactive titanium and nickel in Cassiopeia A. The computer models yield strong support for the theoretical idea that such stellar death events can be initiated and powered by neutrinos escaping from the neutron star left behind at the origin of the explosion.
With complex radiation-hydrodynamical simulations scientists at MPA demonstrate that “pre-supernova feedback” by the intense radiation and stellar winds from massive O and B type stars changes the multi-phase structure of the interstellar medium. While the efficiency of star formation is reduced by “pre-supernova feedback”, individual supernovae explode in lower density environments with enhanced impact.
It is widely known that our planet Earth and the Solar System itself are embedded in the Milky Way, and it is through this galaxy that we look out onto the Universe. Our Galaxy’s gravitational field and its non-uniformity limit the accuracy of astrometric observations of distant – extragalactic – objects. An international group of astrophysicists including a researcher at the Max Planck Institute for Astrophysics tried to find out how strong this effect is.
Researchers at MPA and in other institutions worldwide devised a new way of simulating the impact of large-scale primordial perturbations in the dark matter distribution on the abundance of structures observed at late times, the so-called separate universe simulations. Using this technique, the MPA researchers recently obtained some of the most precise measurements of the local bias, confirming the known trend that more massive halos are more biased than smaller halos.
Researchers using the Atacama Large Millimeter/submillimeter Array (ALMA) successfully imaged a radio “hole” around a galaxy cluster 4.8 billion light-years away. This is the highest resolution image ever taken of such a hole caused by the Sunyaev-Zel'dovich effect (SZ effect). The image proves ALMA’s high capability to investigate the distribution and temperature of gas around galaxy clusters through the SZ effect.
Each year since 2002, analysts at Clarivate Analytics (formerly Thomson Reuters) mine millions of citations in the Web of Science to identify top-tier researchers in physiology, medicine, physics and chemistry as well as economics. MPA director Rashid Sunyaev is one of five 2017 physics laureates for his “profound contributions to our understanding of the Universe, including its origins, galactic formation processes, disk accretion of black holes, and many other cosmological phenomena.”
Using strong gravitational lensing, Simona Vegetti aims to constrain the properties of dark matter and investigate the formation of structure in the universe. Recently, she has been selected as recipient of an ERC starting grant, which will allow her to expand her group and refine her unique modelling technique as well as applying this to new, high-quality data.
Gravitational waves have become a very hot topic in astrophysics since their detection by LIGO in 2015. This means that also possible precursors are in the focus of research – general relativistic research because these objects are either black holes or neutron stars. The 2017 Biermann Lecturer, Masaru Shibata from the Kyoto University, uses numerical simulations and general relativity (or numerical relativity for short) to study the merger of such extreme objects and the properties of both the electromagnetic radiation and gravitational waves emitted during these events.