Tracking the forces of the big bang with rontgen rays: the german telescope erosita will give researchers a new illuminating look at the dark energy of the universe. In the end, erosita is supposed to provide a map of the sky that depicts the universe and its development in unprecedented qualitat.
On 21.6. A russian rocket is to carry the telescope into space from the baikonur spaceport as part of the spektrum-RG space observatory. Researchers talk about the first bilateral russian-german space project.
The hopes are rough. "I don’t want to say that we will solve the mystery of this dark energy, but we are at least on its trail," says peter predehl, scientific director of erosita at the max planck institute for extraterrestrial physics in garching near munich. "The telescope offers huge potential."
Erosita (extended roentgen survey with an imaging telescope array), built under the leadership of the garching institute with the participation of other institutions in germany and russia, is to make the evolution of the universe and its structures visible via rontgen radiation. Because light from distant galaxies travels a long way, the telescope can look back up to six billion years. "We can look into the past and we can see: what did the universe look like then, what does it look like now," says predehl.
The key is galaxy clusters, collections of thousands of individual galaxies bound together by gravity. "Galaxy clusters form a coarse-space structure that resembles a cosmic network," says predehl. The distribution of galaxy clusters shows how the universe has been expanding since the big bang. That is determined mabgeblich by the dark energy, which remains further invisible. For erosita, the forces of 100 million degrees of hot gas in the galaxy clusters are detectable: the temperature is so high that the gas emits rontgen radiation, which erosita absorbs.
"The higher the objects, the more energetic their radiation," says thomas mernik, project manager at the german aerospace center (DLR), which concluded the contracts with the russian space agency roskosmos and financed erosita together with the mpi. The telescope will not primarily observe individual galaxy clusters. "We are scanning the entire sky and will be able to create a map of the sky based on this data," says mernik. The dynamics of galaxy clusters allow conclusions to be drawn about the dynamics of the universe as a whole. "This will help to better understand the nature of dark energy."
About 100.Erosita is to identify 000 galaxy clusters within four years and determine their distribution in the universe. Erosita thus continues the research of the german satellite rosat, which provided data from space for eight years and sank in the indian ocean in 2011, having reached the end of its service life. Rosat had found, among other things, more than 150,000 new cosmic rontgen sources. With new technology, erosita is twenty times more sensitive than rosat. Seven mirror systems form the optics. At the focal point of each mirror system sits a highly sensitive camera developed specifically for the mission.
US researchers had founded the field of rontgen astronomy in 1948, when they discovered the rontgen radiation of the sun during a high flight of a captured german V2 rocket. Previously, rontgen radiation outside the atmosphere was unknown. Because the earth’s air sleeve keeps the rays out. Observatories like spektrum-RG, which besides erosita carries the russian telescope ART-XC, are therefore stationed on satellites. ART-XC and erosita measure in different energy ranges and will sometimes interact when observing galaxy clusters.
After the launch from baikonur, the researchers will first check the instruments. After three months, erosita will reach the target area at a distance of about 1.5 million kilometers from earth. "First results can perhaps be expected at the beginning of september," says predehl.
Even erosita will not be able to directly show dark energy and dark matter, which together make up 95 percent of the universe, but only the effect of their forces. The largest part of the universe remains a mystery. Predehl: "dark means here: we don’t know."