The super Map of Dark Matter
Exploiting the effect of the gravitational lens and the power of the instrumentation of the Space Telescope, a team of scientists has managed, a few years ago, to reconstruct the distribution of dark matter in the cluster of galaxies called Abell 1689 with unprecedented detail.
A few years ago we had the news of the discovery of five galaxies in the early universe exploiting the phenomenon of gravitational lensing observations with the Herschel satellite. With the same methodology, but with the observations of the Hubble Space Telescope, a team of astronomers has managed to draw more detailed map to date of dark matter, the invisible and enigmatic element that seems to constitute the majority of the mass of ‘universe.
Dan Coe of NASA’s Jet Propulsion Laboratory in Pasadena, California, along with other researchers, has harnessed the power of Hubble’s Advanced Camera for Surveys to track the distribution of invisible matter in the massive galaxy cluster called Abell 1689, which lies 2.2 billion light years from us. The gravitational pull generated from storage deflects the light radiation produced by the galaxies that lie behind the cluster with respect to our line of sight, thus acting as a real lens. This effect is more intense the higher the concentration of matter – visible but especially dark – which is located in the cluster. And considering this effect, astronomers have estimated the amount of dark matter in Abell 1689, finding that in the central area of storage under its concentration is much greater than indicated by the computer simulations. It is a surprising discovery, which was advanced by a few billion years the time when this cluster should be formed.
This map proved a veritable mine of information on the role of dark energy in the early stages of formation of the universe. First analyzes of data emerge indeed in important indication that galaxy clusters can therefore be formed more quickly than previously thought, before the effects produced by dark energy body block their growth. Dark energy – the more enigmatic “actor” in the evolution of the universe – in fact plays an antagonistic role to the gravitational pull exerted by dark matter. The dark energy galaxies are getting away from each other, stretching the space between them and effectively blocking the formation of large scale structures such as clusters of galaxies. And just to understand how it is done this tug of war between opposing forces is immeasurable certain to know what was the distribution of dark matter in the early universe.
To investigate more thoroughly these fundamental aspects to reconstruct the evolution of the universe and its structures in the first billion years after the Big Bang, astronomers are planning new observational campaigns on other clusters of galaxies to study the influence of dark energy. A major program of Hubble, which will analyze the dark matter in galaxy clusters, is the Cluster Lensing and Supernova survey with Hubble (CLASH). In this survey, the space telescope will study 25 clusters, for a total of a month cumulative observations, distributed over the next three years. The galactic agglomerates which were selected emit intense flows of X-rays, the signal of the presence of large quantities of hot gas inside them and therefore of great mass concentrated in them, just as Abell 1689.