Catherine Heymans describes dark matter’s effect on galaxies

Catherine Heymans: You can’t listen to just the wind section of a symphony orchestra if you want to hear the full music.

Astronomer Catherine Heymans of the University of British Columbia is talking about how astronomers look beyond visible light – the light we can see – to study the universe. With the Hubble telescope, Heymans collected radio waves, ultraviolet, and infrared radiation coming from the Abell supercluster of galaxies 2.6 billion light-years from Earth.

Catherine Heymans: What we’re finding is very dense pools of dark matter that are pulling galaxies into this dense region of space.

Astronomers think that 85 percent of all matter in the entire universe is made of what they call ‘dark matter,’ which cannot be seen. They know dark matter by its gravity, which in the Abell supercluster yanks entire galaxies around.

Catherine Heymans: We can see galaxies changing as we go from the outskirts of the supercluster, like the suburbs of the city, into the center of the city, or the densest parts of the supercluster.

Closer to the ‘downtown’ of the supercluster…

Catherine Heymans: We’ve got great names. There’s a ‘strangulation,’ there’s ‘tidal stripping’ where their gas is ripped out of them as they fall onto hot gas.

Heymans said that the shadowy forces of gravity from dark matter pull these galaxies together, sometimes to the point where whole galaxies crash into each other.

Our thanks to:
Catherine Heymans
University of British Columbia
Vancouver, Canada

May 20, 2008

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