Galaxy formation in separate universes

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

<p>Cool dense hydrogen gas around the first quasars</p>

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

<p>Globular cluster formation deciphered</p>

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

Viscosity of hot gas in galaxy clusters

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

The hidden satellites of the first massive galaxies and quasars

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

X-ray emission from Warm-Hot Intergalactic Medium

The Warm-Hot Intergalactic Medium contributes substantially to the matter budget in the Universe – but it is only poorly studied, as it is very difficult to observe. Researchers at MPA have now predicted how it can be explored using heavier elements as tracers. Due to scattering of the cosmic X-ray background some of this line emission can be boosted substantially and should be accessible by the upcoming X-ray survey missions. more

Heat conduction in the Interstellar Medium

A team of researchers from the Max Planck Institute for Astrophysics, the University Observatory Munich, and collaborators have investigated the effect of heat conduction on the evolution of supernova blast waves and the structure of the supernova-driven interstellar medium (ISM). They find that thermal conduction has a strong impact on the volume filling fractions of cold, warm and hot gas. Thermal conduction also plays an important role for an accurate description of the hot ISM phase structure and the chemical composition of the cold phase of the turbulent ISM. more

Towards a complete model of the interstellar medium

For the first time MPA scientists and European collaborators have simulated the solar neighborhood interstellar medium (ISM), including physical processes following all major thermal and non-thermal components - ionized, neutral and molecular gas, dust, interstellar radiation, magnetic fields, and cosmic rays in the presence of star formation. As the different processes strongly influence each other, the simulations highlight the importance of including them all, in particular radiation and cosmic rays, for a realistic model of the star-forming ISM. Within the Gauss Center for Supercomputing (GCS) project SuperSILCC the team will use SuperMUC-NG, one of the world’s fastest supercomputers, to reveal the physical origins of the ISM structure also in extreme environments at high redshift. more

<p>Sloshed and shocked: diagnosing gas motion in galaxy clusters</p>

Recent high-resolution microwave and X-ray observations of the galaxy cluster RX J1347-1145 offer a new diagnosis tool of gas motion. Probing different parameters of the hot gas in galaxy clusters, these observations allow the MPA scientists to distinguish between gentle and violent motion of gas stirred by encounters with smaller sub-clusters. more

Galaxy physics beyond the halo boundary

Models of the large-scale structure of galaxies in the Universe suffer from serious limitations, when artificial boundaries are imposed at the virial radius of the dark matter halo. As MPA scientists demonstrate, environmental effects vary smoothly across the traditionally adopted halo boundary and need to be taken into account even in low-density environments. more

<p style="margin-bottom: 0cm;">Next generation imaging</p>

Next generation imaging

February 01, 2019

The Information Field Theory Group at the Max Planck Institute for Astrophysics has released a new version of the NIFTy software for scientific imaging. NIFTy5 generates an optimal imaging algorithm from the complex probability model of a measured signal. Such algorithms have already proven themselves in a number of astronomical applications and can now be used in other areas as well. more

<p>Dynamo-amplification and magnetic driven outflows in Milky Way-like galaxies</p>

Lately, the impact of magnetic fields in simulations of galaxy formation and evolution is being widely studied. However, it is still unclear to which degree magnetic fields influence the formation and evolution of galaxies. A team of researchers from the astronomical Max Planck Institutes in Garching, the University Observatory in Munich, and the University of Konstanz have introduced a new galactic model with an explicitly modelled circum galactic medium (CGM) to investigate the impact of magnetic fields in an isolated simulation of a Milky Way-like galaxy with the focus on the dynamo amplification of the magnetic field. Further the researchers discuss the possibility of bi-conical magnetic driven outflows and their impact on the star formation rate of the galaxy. more

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