International scientific think-tank under supervision of Alexei Vikhlinin (Institute of Space Research, Russia) performed experiments, which confirmed that the Universe expands with acceleration, and showed how it developed in time. Currently astronomers are developing new orbital X-ray observatory with one of the tasks of performing necessary measurements of “dark energy” with unprecedented accuracy.

In the end of the previous century scientists have observed distant supernovas and showed that our Universe expands with acceleration. The reason for such phenomenon is so-called “dark energy” or “invisible energy”, which properties are shown to be quite unusual. For instance, dark energy should have had negative pressure for “boosting” the Universe. Nature of dark energy is one of the main mysteries of modern physics, since this phenomenon determines how our world will develop.

Scientists studied distribution of massive galactic clusters, which are main components of large-scale structure of our Universe, in space. Large-scale structure of our Universe consists of abovementioned galactic clusters, bonded by filaments – gas clouds separated by empty spaces. Dark energy is believed to have great effect on growth of Universe’s large-scale structure, since it resists gravitational attraction of matter and prevents matter accumulation on large distances. This effect is more clearly seen on the formation speed of massive galactic clusters. Such clusters contain thousands of galaxies, similar to the Milky Way, and can have masses equal to 1014 our Suns.

Researchers discovered and then studied 86 most massive galactic clusters, which are located as far as millions and billions light years from our home galaxy. The majority of said galaxies was discovered by means of the ROSAT (X-ray) telescope, the joint project of Germany the US and the UK. Most distances were measured with help of several optic telescopes all around the world: Keck, Magellan, NTT and etc. Russian and Turkish joint telescope RTT-150 also contributed a lot to galaxy studies, but the major tool of the project was “Chandra” X-ray observatory, which data helped obtaining exact measurements of cluster masses.

Heaps of data allowed astrophysicists to create a model of the Universe development, starting with about 60% of its age till now, in other words during last 5.5 billion years – approximate age of the Sun, by the way. This experiment revealed that during this period of time the growth of the large-scale structure significantly dropped.

Dark energy “pushes away” matter with force, which is similar to spring force and is described with a parameter of dark energy state equation. Scientists now possess the most accurate value of said parameter, which implies that equations of general relativity work on all distances – from planets radiuses to the observed part of the Universe.

Russian scientists are now in promising collaboration with international colleagues, and their work is aimed at creating an orbital X-ray observatory “Spectra-roentgen-gamma” and launching it to the orbit in 2012. The observatory will study the sky and is expected to detect about 100 thousand new galactic clusters (e.g. all massive clusters in our Universe), about 3 million of nuclei of active galaxies (superheavy black holes) and 2 million of coronally active stars. The results will give exact data on how fast the Universe structure grows, and then help correctly determine dark energy state equation.

Researchers expect new data on dark energy to contribute to the new theory of vacuum, which may show, that our space has five dimensions instead of four.

Source: Science & Life

Kizilova Anna