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.
In collaboration with researchers from the USA, MPA scientists have mounted a series of ambitious experiments that use a combination of quasar absorption-line spectra, neutral hydrogen line data, and state-of-the-art cosmological hydrodynamical simulations to probe the interface between galaxies and their surrounding gaseous environment. The researchers found that galaxies with gas-rich disks are embedded within gas-rich halos and that the gas in these halos is distributed smoothly and relatively isotropically.
Supernovae are extremely bright stellar explosions – superluminous supernovae are even brighter. In a new study, MPA researchers present their simulations of superluminous supernova spectra months and even years after the outbreak and show that they are very similar to gamma-ray bursts, another type of highly energetic explosions. In addition, the results point to very high masses of oxygen and magnesium, suggesting very massive progenitor stars.
By using galaxies as giant gravitational lenses, an international group of astronomers including researchers at the MPA have made an independent measurement of how fast the Universe is expanding. The newly measured expansion rate for the local Universe is consistent with earlier findings - but in intriguing disagreement with measurements of the early Universe. This hints at a fundamental problem at the very heart of our understanding of the cosmos.
The origin of the current accelerated expansion of the Universe remains one of the major unsolved mysteries in physics today. While this could be a sign of the mysterious “Dark Energy”, it might also be evidence for the inadequacy of Einstein’s theory of General Relativity (GR). Researchers at MPA and MPE created mock universes with non-GR theories of gravity to test the validity of current observational methods. This allowed them to place bounds on how much the current data allows the Universe to depart from Einstein’s prediction.
Why do galaxies in enormous galaxy clusters look different from normal, isolated galaxies? To answer this question, an international research team led by MPA has created the Hydrangea simulations, a suite of 24 high-resolution cosmological hydrodynamic simulations of galaxy clusters containing over 20,000 individual galaxies. These simulations provide astrophysicists with a powerful new tool to understand how galaxies formed and evolved in one of the most extreme environments of our Universe.
Researchers from the Max Planck Institute for Astrophysics and the University of Amsterdam just published the most precise analysis so far of the fluctuations in the gamma-ray background. They used more than six years of data gathered by the Fermi Large Area Telescope and found two different source classes contributing to the gamma-ray background. No traces of a contribution of dark matter particles were found in the analysis.
As in previous years at the end of April, MPA invited 30 girls to learn more about astronomy and what it means to pursue a career in science. This event was part of the annual Girls’ Day, an initiative throughout Germany to encourage girls to learn more about occupational areas that are still male dominated. Even though the weather did not cooperate, the girls were very active and braved the cold and the rain to visit the roof telescope and launch their “rockets”.