The Mystery of the "Missing Dwarf Galaxies"
High-precision observations over the last two decades have indicated that our Universe consists of about 75% Dark Energy, 20% Dark Matter and 5% ordinary matter. Galaxies and matter in the universe clump in an intricate network of filaments and voids, known as the Cosmic Web. Computer experiments on massive supercomputers have shown that in such a Universe a huge number of small "dwarf" galaxies weighing just one thousandth of the Milky Way should have formed in our cosmic neighbourhood. Yet only a handful of these galaxies are observed orbiting around the Milky Way. The observed scarcity of dwarf galaxies is a major challenge to our understanding of galaxy formation.
"The main goal of this project is to simulate the evolution of the Local Group - the Andromeda and Milky Way galaxies and their low-mass neighbours - within their observed large scale environment", said Stefan Gottlöber of the Leibniz Institute for Astrophysics Potsdam.
The image below shows a Cosmic Web Stripping removes gas from a very fast dwarf galaxy crossing the local web. The image is a visualization of a CLUES simulation. The arrow symbolizes the velocity oft he dwarf, located right below. Analysing the CLUES simulations, the astronomers have now found that some of the far-out dwarf galaxies in the Local Group move with such high velocities with respect to the Cosmic Web that most of their gas can be stripped and effectively removed. They call this mechanism "Cosmic Web Stripping", since it is the pancake and filamentary structure of the cosmos that is responsible for depleting the dwarfs' gas supply.
"These dwarfs move so fast that even the weakest membranes of the Cosmic Web can rip off their gas", explained Alejandro Benítez LLambay, PhD student at the Instituto de Astronomía Teórica y Experimental of the Universidad Nacional de Córdoba in Argentina, and first author of the publication of this study. Without a large gas reservoir out of which to form stars, these dwarf galaxies should be so small and dim that they would be hardly be visible today. The missing dwarfs may simply be too faint to see.
The study of Benítez Llambay and colleagues is published in the February issue of Astrophysical Letters. More information: Benítez-Llambay, A. et al. Dwarf galaxies and the Cosmic Web, Astrophysical Letters. doi:10.1088/2041-8205/763/2/L41.
The image at the top of the page shows a small galaxy, UGC 5288, 16 million light-years from Earth surrounded by a huge disk of hydrogen gas that has not been involved in the galaxy's star-formation processes and may be primordial material left over from the galaxy's formation captured by the National Science Foundation's Very Large Array (VLA) radio telescope.The Daily Galaxy via Leibniz Institute for Astrophysics Potsdam
Image credit: Alejandro Benítez Llambay
Comments
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question. is the reason that we can not see dark matter is because it moves faster than the speed of light, and therefore on a different spectrum to the ones that we know off
Posted by: lawrence | February 01, 2013 at 07:47 AM
And one more mystery? WHEN will its stop ? What do the scientists really know? No much by the looks of things.
Posted by: Knize10 | February 01, 2013 at 10:32 AM
Dark matter and energy do not exist,if you axept multy space teory.Universes around us affest on it,and show us a false metering.
Posted by: Montenegringo | February 02, 2013 at 06:03 AM