Dark matter distribution mapped
24 Sep 2015 by qwwqdccwwm.d qwwqdccwwm.d
New images reveal the amount of dark matter in the Universe and its distribution in distant galaxies.
Astronomers led by Leiden University in the Netherlands used images captured by the VLT Survey Telescope at the European Southern Observatory in Chile and discovered that galaxies contain 30 times more dark matter – invisible material that accounts for 80% of all matter in the Universe – than the visible matter seen in stars.
Research associate, Dr Peder Norberg said: “This is a first step towards better understanding the relationship between visible and dark matter, which is only made possible thanks to sophisticated instrumentation and the significant efforts of our international team of scientists.”
In the study, published in the journal Monthly Notices of the Royal Astronomical Society, the researchers used data from the Kilo-Degree Survey and distance information of foreground galaxies measured by the Galaxy and Mass Assembly survey in Australia. They analysed images of more than 2 million galaxies, typically 5.5 billion light years away and combined them with data of 20,000 known groups of galaxies.
The team studied how light from galaxies is distorted by the gravitational pull of massive clumps of dark matter in order to map the matter distribution in the Universe and measure the influence of dark matter on the shape of galaxies.
The results showed that the brightest galaxy in each group nearly always sits at the centre of the dark matter clump that surrounds it, in line with previous theories of galaxy formation.
Dr Massimo Viola, who led the study, said: “We look forward to making many more discoveries about this most elusive of substances, dark matter, in the months ahead.”The scientists believe their findings will help them understand dark matter and how galaxies are formed, as well as create map of the invisible substance.
Paper: http://arxiv.org/abs/1507.00735