Mysterious matter here and there
Dear reader, the distant collision of two neutron stars not only triggered gravitational waves, but sparked a veritable electromagnetic fireworks display that was observed in August 2017. A black hole is believed to have formed as a remnant of this cataclysmic event, dubbed GW170817. Heavy chemical elements such as gold and lead were also formed in the process. Such neutron star accidents are of great importance for research.
Because it is still a mystery to astronomers what exactly is inside neutron stars. Sure, it's mostly neutrons that give the compact remnants of massive stars their names. But what happens to the neutrons at even higher densities? Do they break up into individual quarks? Or are they morphing into something even more exotic, strange matter? Astrophysicists are on the trail of these mysteries and are hoping for a solution, above all, from the now measurable gravitational waves. From page 26 you can learn more about the densest forms of matter in neutron stars.
Cosmologists are also struggling to understand matter, but it is obscure in their discipline. This also applies to dark energy, which, due to its anti-gravitational effect, allows the universe to expand at an accelerated rate. But a new beacon of hope is emerging, because the X-ray astronomers have now sent the eROSITA satellite into the running to unravel the dark cosmos. We report on the start and finish of the mission on page 38.
The short reports in this issue also deal with neutron stars and cosmology. A new controversy about the Hubble constant is raging, and we have to ask ourselves again how fast the universe is currently expanding.
To solve all these mysteries, astronomy needs young people – especially more women. The interview with this year's Roelin Prize winner, Sibylle Anderl, on page 34 shows just how varied paths in science can be.
Hush into the magazine! Yours
Andreas Müller</p<
