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Astrophysics Seminar

Tuesday May 13, 14.30, HPF G6

Professor John Peacock, University of Edinburgh

"Studying large-scale structure with the 2dF Galaxy Redshift Survey"

Abstract:

The 2dF Galaxy Redshift Survey was the first to observe more than 100,000 redshifts, making possible precise measurements of many aspects of galaxy clustering. The spatial distribution of galaxies can be studied as a function of galaxy spectral type, and also of broad-band colour. This talk concentrates on measurements of the clustering power spectrum, and how this allows us to measure the matter content of the universe. In combination with measurements of aniostropies in the microwave background, all the main cosmological parameters can be measured - breaking the degeneracies inherent in a CMB-only analysis. This analysis proves that the universe is very close to flat. The matter content is accurately consistent with pure Cold Dark Matter, with about 25% of the critical density, and fluctuations that are scalar-only, adiabatic and scale-invariant. It is demonstrated that these conclusions cannot be evaded by adjusting either the equation of state of the vacuum, or the total relativistic density.

There will also be a broadly related Theoretical Physics Seminar later the same afternoon (1630 HPZ E9)

Professor Neil Turok, University of Cambridge

`Beyond Inflation: Developing a Cyclic Model of the Universe'