Current Research Highlights

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

Warm, cold, just right? The analysis of seven strongly gravitationally lensed quasars gives new clues about the temperature of dark matter, the mysterious substance that makes up about a quarter of our universe. The results put a lower limit on the mass of a potential dark matter particle while not ruling out cold dark matter. more

A new model of galaxy formation will help scientists to better understand the distribution of gas and stars within galaxies. Researchers from the MPA in Garching, along with collborators from Switzerland, China, the UK, and Iceland have come together to release L-GALAXIES 2020, the latest version of the L-GALAXIES model project, a computational simulation designed to study many millions of galaxies simultaneously, each self-consistently evolved over billions of years of cosmic time. more

Artificial intelligence expands into all areas of the daily life, including research. Neural networks learn to solve complex tasks by training them on the basis of enormous amounts of examples. Researchers at the Max Planck Institute for Astrophysics in Garching have now succeeded in combining several networks, each one  specializing in a different task, to jointly solve tasks using Bayesian logic in areas none was originally trained on. This enables the recycling of expensively trained networks and is an important step towards universally deductive artificial intelligence. more

By examining the Auriga suite, a large sample of simulated Milky Way galaxies formed in the full cosmological context, scientists at MPA have been able to place constraints on the history of the Milky Way's formation. By comparing these simulations to observations of the Milky Way — and specifically to how fast stars of different metallicities in the inner regions of the Galaxy move around its centre — they were able to exclude certain formation histories. In particular they found that our galaxy had to be quite isolated with the last major merger happening over 12 billion years ago and with a galaxy less than 10% of the mass of the Milky Way. more

Rather than trying to study special regions in large-volume simulations, scientists at MPA have used the IllustrisTNG model to create whole separate universes with a modified cosmology. Their study of these separate universes shows that when the baryon density (the density of ordinary matter) changes, the number of galaxies can increase or decrease depending on how this number is measured. Also, the large-scale distribution of matter is affected by the effects of baryons, with various measures reacting differently. more

Quasars are amongst the brightest non-transient sources in the sky. Thanks to their high luminosity, they can be observed even at early cosmic times, where – surprisingly – these first quasars appear as already evolved systems: with black holes with masses exceeding one billion solar masses hosted by massive and heavily star forming galaxies. To explain such rapid growth, theorists believe these systems must reside in peculiarly dense environments, where huge gas reservoirs favour efficient inflow of material onto seed super-massive black holes. An international team of astronomers has recently found the first clear observational evidence that this is indeed the case. The new “panoramic” spectrograph called MUSE unveiled, for the first time, the almost ubiquitous presence of large amounts of cool gas in close proximity to the first quasars. This pristine fuel will fall on the primordial galaxies and sustain their growth in both stellar and black hole mass. more

Globular clusters are the densest gravitationally bound stellar systems in the Universe. They are found in all galaxy types, even low mass dwarf galaxies and they can be almost as old as the Universe. The formation mechanisms of these enigmatic systems are not yet understood. Scientist at MPA and the University of Helsinki, together with international collaborators, have now presented the first hydro-dynamical simulation at sub-parsec resolution following the entire formation history of spatially resolved globular cluster candidates in merging dwarf galaxies. This provides a general model for the formation of metal-poor globular clusters in chemically unevolved starbursting environments of low-mass galaxies at high redshifts. more

Hot plasma fills the entire volume of galaxy clusters and makes these objects powerful sources of X-ray radiation. While the density and temperature of this gas can be readily measured, its material properties, such as its viscosity and thermal conductivity are largely unknown. The problem stems from the poorly understood role of weak magnetic fields permeating the gas. While such fields are too weak to directly affect large-scale motions of the gas, they might change the microscopic properties of the plasma. Recent long observations of the Coma cluster in the X-ray band have shown that this is indeed the case – the behavior of the gas is markedly different from expectations for un-magnetized plasma. more

New cosmological simulations targeting the evolution of the first quasars and their host galaxies now follow the effects of radiation from young stars on the interstellar medium. As the international team shows, stellar radiation can alter both the properties of the quasar host galaxy and its satellites, making them more diffuse and less tightly-bound. Satellites are more easily disrupted by the strong tidal forces of the massive central galaxy, which therefore contains a smaller satellite population. more

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