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Lecture 26

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Laura Parker

Lecture 26Tuesday November 15 20111230 PMThe Dark universe70 of the universe is dark energy25 is dark matterLess than 1 is neutrinos4 is hydrogenheliumLess than 1 are starsEvidence for dark matterMotions of galaxies in clusters1Spiral galaxy rotation curves1Gravitational lensing1Galaxies do not rotate as if all their mass were in the visible stars left but instead rotate at almost a constant rate no matter the distance from their centres Right90 of the mass in galaxies clusters etc is dark matterDM goes beyond the galaxies shown by spiral galaxy rotation curves and gravitational lensingModes of things connected by filaments to other nodes high density and low density90 of the mass in the large scale of the universe is dark matterWMAP to the network is due to time and gravity3 independent lines of evidence that mass in luminous material is a small fraction of the total massIn other words mass in stuff we can see is way less than the mass implied by gravityWithout dark matter CBR fluctuations would be different large scale structure would look differentWe can also estimate the amount of DM by looking at large scale structureMore dark matter means gravity would have had a more dramatic effect more clusters more large structuresLess dark matter no time for large objects like clusters to have formedWhat is dark matter ASTRON 2B03 Page 1
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