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TOPIC: Cosmic Web Stripping

Blobrana

L

Posts: 131433

Date: Feb 1 21:42 2013

Missing dwarf problem	Permalink

Astronomers of the international CLUES collaboration have identified "Cosmic Web Stripping" as a new way of explaining the famous missing dwarf problem 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. Read more __________________

Blobrana

L

Posts: 131433

Date: Jan 31 02:20 2013

RE: Cosmic Web Stripping	Permalink

Title: Dwarf Galaxies and the Cosmic Web Authors: Alejandro Benitez-Llambay, Julio F. Navarro, Mario G. Abadi, Stefan Gottloeber, Gustavo Yepes, Yehuda Hoffman, Matthias Steinmetz We use a cosmological simulation of the formation of the Local Group of Galaxies to identify a mechanism that enables the removal of baryons from low-mass halos without appealing to feedback or reionisation. As the Local Group forms, matter bound to it develops a network of filaments and pancakes. This moving web of gas and dark matter drifts and sweeps a large volume, overtaking many halos in the process. The dark matter content of these halos is unaffected but their gas can be efficiently removed by ram-pressure. The loss of gas is especially pronounced in low-mass halos due to their lower binding energy and has a dramatic effect on the star formation history of affected systems. This "cosmic web stripping" may help to explain the scarcity of dwarf galaxies compared with the numerous low-mass halos expected in \Lambda CDM and the large diversity of star formation histories and morphologies characteristic of faint galaxies. Although our results are based on a single high-resolution simulation, it is likely that the hydrodynamical interaction of dwarf galaxies with the cosmic web is a crucial ingredient so far missing from galaxy formation models. Read more (764kb, PDF) __________________

Blobrana

L

Posts: 131433

Date: Jan 31 02:18 2013

	Permalink
Cosmic Web Stripping removes gas from a very fast dwarf galaxy crossing the local web. See more __________________

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