The days are numbered for the dark matter?
The correlation between the distributions of ordinary matter, derived from observations of galaxies, and dark matter that agrees with the predictions of cosmological models that take into account the effect on expanding cosmic dark energy. And what emerges from a study published in Physical Review Letters.
For dark matter could be really difficult to play hide and seek. Today, an international group of researchers has published the first data relating to a new map of the spatial distribution of dark matter using data obtained from the Dark Energy Survey (DES). The results, published in Physical Review Letters, suggest that the relationship between the visual map of the distribution of galaxies and that relating to the distribution of the mass is very close to that predicted by models based on cosmological simulations that include the accelerated expansion of the Universe.
Credit: Dark Energy Survey
The hunt for dark matter has no respite. Recently we wrote on these pages the project VST KiDS and early results based on observations in the southern hemisphere due to VLT Survey Telescope (VST), the wide-field telescope of view created by Astronomical Observatory of Capodimonte , and installed next to the Very Large Telescope at the Paranal Observatory in Chile. The Kilo Degree Survey will, in fact, to achieve accurate measurements of dark matter, the structure of the halos of galaxies thus obtaining new clues to the evolution and formation of galaxies and clusters themselves in which they reside.
But back to the DES, currently in progress at the Blanco telescope located in Chile. It is a cosmological survey that has been developed to look at about 1/8 of the visible sky. The main purpose of the survey is to better characterize the nature of energy dark, enigmatic component that seems to be responsible for the accelerated expansion of the Universe. These maps, created with one of the more powerful digital cameras in the world, are the most important project of mapping contiguous, with a level of detail that promises to significantly improve our understanding of the process of galaxy formation and the role that dark matter plays (see the dark matter in the plant).
Now, one way to do this is to study the distribution and evolution of dark matter. Scientists estimate that ordinary matter constitutes only 1/5 of the total mass in the universe, the rest is just “dark”, an appropriate term because this substance does not absorb or emit light. “Scientists need to resort to very precise measurements of the spatial distribution of all matter in the universe so as to achieve accurate experiments,” says Vinu Vikraman, post-doctoral researcher at the US Department of Energy’s Argonne National Laboratory and co-author of the study. “We do not know what really dark matter nor can we locate it directly. This map represents a tool of fundamental importance for cosmology as it will give a number of answers to these questions, including those concerning precisely the origin and nature of dark energy. ”
Credit: Vinu Vikraman / Argonne National Laboratory
To indirectly reveal the dark matter, scientists have come up with a method that is based on the construction of a map of the distribution of the mass obtained by DES through a series of measures obtained by analyzing the effect of the weak gravitational lensing or weak lensing. It is a phenomenon expected from general relativity in which the light rays from distant objects are deflected from the distribution of the material that surrounds the galaxies. This effect creates a distortion or deformation of the image of a galaxy that astronomers can measure to determine how matter is distributed object that acts as a gravitational lens. The researchers then compared the map obtained by the mass distribution with a new optical map of the distribution of galaxies ever obtained from the survey DES. This information allowed the researchers to look for any patterns in the distribution of both the galaxies of dark matter. “This allowed us to check the consistency of our work as we expect that the distribution of galaxies follows the dark matter,” says Vikraman. These preliminary results, in fact, suggest that the relationship between the visual map of the distribution of galaxies and that relating to the distribution of the mass is very close to that predicted by models based on cosmological simulations that include the accelerated expansion of the Universe. Recall, finally, that the survey DES is designed to cover a region of the sky amounting to more than 36 times the area obtained from this first map. It is hoped, therefore, that this new set of data in the future may provide valuable clues to understand even better the nature of dark energy.