Current Research Highlights

Peculiar white dwarf mergers

Two types of hot, blue and dense stars that show peculiar characteristics in their composition and vibrations have posed a challenge to astrophysicists for more than a decade. A team of scientists from MPA and La Plata in Argentina, has now been able to explain both types as a product of very similar merger events. In particular, the scientists think that the peculiar hot and blue stars are formed by the merger of two white dwarfs. more

New analysis strengthens the hint of new physics in polarized radiation from the early Universe<br /> 

In 2020, a tantalizing hint of new physics violating “parity symmetry” was found in polarization data of the cosmic microwave background obtained with the Planck satellite at high frequencies. Based on the Planck data and a simplified assumption about the impact of the polarized dust emission in the Milky Way, the scientists reported a violation of the symmetry of the laws of physics under inversion of spatial coordinates with 99.2% confidence level. An international team led by MPA director Eiichiro Komatsu has now improved the analysis method. By considering the dust emission explicitly and using more data from not only Planck but also from WMAP the astrophysicists measured the parity-violating signal with 99.987% confidence level. If this should be confirmed in the future as a genuine cosmological signal, it would have profound implications for the fundamental physics behind dark matter, dark energy, and quantum gravity. more

Reflected quasar light powers giant cool gas nebulae

Already in the early Universe, supermassive black holes with masses a billion times larger than the Sun appear to inhabit the centres of massive galaxies. As interstellar gas is accelerated in their powerful gravitational field, it emits copious amounts of radiation, outshining the entire galaxy as “quasars”. Recent observations have revealed that the first quasars are often surrounded by bright, giant nebulae. These can span up to several 100,000 light years, about ten times larger than their host galaxy. New detailed computer simulations of galaxy evolution performed at MPA have shed new light on these puzzling observations, reproducing them in striking detail. According to these new theoretical models, the observed extended nebulae can be explained as quasar light that reflects off cool neutral hydrogen clouds surrounding the quasar host galaxy. Crucially, this mechanism only works if the energy provided by the quasar is able to produce gigantic galactic winds that blow out large masses of gas from its immediate vicinity. This finding suggests that quasars shape galaxy evolution from the earliest stages of galaxy formation. more

Do massive red elliptical galaxies line up?

Are galaxy orientations distributed randomly in the cosmos? What appears to be a simple question might not only shed light on our understanding of galaxy and cluster formation, but also further our knowledge of cosmological models. MPA scientists and collaborators attempt to settle this question through the first direct, field-based measurement of whether and how massive red elliptical galaxies align with the tidal field of large scale structure. Their result confirms predictions of the (linear) alignment model of galaxy intrinsic alignment. The newly presented method also opens up new avenues for cosmology and astrophysics. more

Inner view of the Milky Way’s magnetic field shows spiral structure

Magnetic fields of spiral galaxies usually show spiral structures themselves. For our own galaxy, this could not be confirmed so far due to our unfavorable inner perspective. Researchers at the Max Planck Institute for Astrophysics have now shown that the local galactic magnetic field is indeed aligned with the local Orion spiral arm of the Milky Way, as expected for a spiral galaxy. more

Nearby galaxy centres with unusual populations of very massive stars

A new study of galaxies with data from the MaNGA survey shows that the initial mass function of stars, i.e. the mass distribution when they initially form, might not be as universal as widely assumed. The MPA study found an excess of very massive stars in some galaxies. An excess of radio sources in the sample might be an intriguing hint that a hidden population of black holes may exist in these galaxies. more

Black hole as video: M87* in time, space and frequency

In April 2017 the Event Horizon Telescope (EHT) observed the super-massive black hole M87* and provided a first image of its shadow that went around the world. Researchers at the Max Planck Institute for Astrophysics have now reconstructed a video of the immediate surroundings of a black hole from the same underlying data. This not only confirms previous findings, it also hints at new structures and dynamics in the gas disk around the black hole. more

<strong>How do </strong><strong>star cluster</strong><strong>s</strong><strong> form in dwarf galaxies?</strong>

In the interstellar medium (ISM) of galaxies, stars form in small groups groups of a few hundred and clusters up to several million stars. A full theoretical model of this process and its impact on galaxy evolution is still in its infancy. MPA researches and their collaborators have developed a highly complex numerical model to simulate the multi-phase ISM and how star clusters emerge in dwarf galaxies. The supercomputer simulations show that the properties of the star clusters depend on how efficiently stars can form from the cold dense gas. Detailed post-processing then allowed the researchers to compare their results to observations. This demonstrates the scientific fidelity of the new model, its current limitations, and observational limitations on how well clusters can be detected in regions of high star formation activity. The studies are a major step towards a comprehensive model for star cluster formation. more

Galaxy formation with L-GALAXIES: modelling the environmental dependency of galaxy evolution

The colours and star formation rates of galaxies are strongly correlated with each other out to distances as large as 10 Megaparsecs. However, current galaxy formation models fail to reproduce these large-scale correlations accurately. Scientists from MPA, the University of Surrey, and Heidelberg University are in the process of updating the Munich galaxy formation model, L-GALAXIES, with a sophisticated and accurate method to model environmental effects for all galaxies. The most recent updated model is in significantly better agreement with observations than its predecessors and exhibits a stronger environmental dependency of galaxy properties out to several Megaparsecs from the centers of their dark matter haloes. more

Galaxy formation meets Reionization in the THESAN simulations

Approximately 13 billion years ago, the radiation produced by the first galaxies completely transformed the Universe. The vast amount of hydrogen filling the space between galaxies was  ionized in a process called cosmic reionization. Despite their intimate connection, the formation of the first galaxies and the reionization process are typically studied separately. An international team led by and including MPA researchers has now produced the first suite of simulations designed to simultaneously investigate these two processes during the infancy of the Universe, unveiling features of their connection. This new numerical effort – soon to be released publicly – provides a unique platform for investigating the young Universe and to fully exploit the forthcoming James Webb Space Telescope. The first results from THESAN have already shown that its unique combination of physical accuracy and simulated scales allows to reproduce most of the available data, including some that escaped previous numerical efforts. more

Probing the interface between infall and outflows in a high-redshift massive halo

Cosmological simulations show that the growth of galaxies in the early Universe is regulated by the interplay between gas accretion onto dark-matter halos and ejection of matter by stars and active galactic nuclei (AGN). While these processes are routinely described in theoretical works, still little is known from observations on the complex exchanges of mass and energy within the halos of galaxies, where large-scale infall (i.e. accretion) meets outflows (i.e. ejection). Recently, an international team of astronomers was able to probe the halo gas of a massive galaxy system, SMM J02399-0136, using a novel approach. These observations unveiled – for the first time – the infall towards the galaxies of a large mass of diffuse, highly turbulent multiphase gas, pervaded by powerful outflows and more than 10 times larger than the star-forming galaxies. more

Teardrop shape reveals supernova fate

Astronomers have made the rare sighting of two stars spiralling to their doom by spotting the tell-tale signs of a teardrop-shaped star. The tragic shape is caused by a massive nearby white dwarf distorting the star with its intense gravity, which will also be the catalyst for an eventual supernova that will consume both. more

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