PIRSA:09060066  ( MP4 Medium Res , MP3 , PDF ) Which Format?
Weighing the Universe
Speaker(s): Neta Bahcall
Abstract: How do we weigh the Universe? Where is the Dark Matter? I will discuss these questions and show that several independent methods, including the observed present-day abundance of rich clusters , the evolution of cluster abundance with redshift, the baryon-fraction in clusters, the observed Mass-to-Light function from galaxies to superclusters, and other large-scale structure observations, all reveal a universe with a low mass density parameter of ~20% of the critical density. The data suggest that the mass in the Universe, including the dark-matter, approximately follows light on large scales and that most of the mass resides in huge dark halos around galaxies. I will review the combined observational evidence for dark-matter and for dark-energy in the universe and their cosmological implications.
Date: 24/06/2009 - 2:00 pm
Tech Note: Large portion roughly 8 minutes in is missing due to fire alarm. Missing portion was edited out. - Jacob W. Stauttener
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