Friday, June 14, 2013

A colloquium by S. White

This morning I attended a talk on the Planck results by S. White, who contributed a lot to the current theories of cosmology and structure formation (White and Rees 1978, the NFW paper, etc.).
It was a brilliant talk, here are some things that stuck:
-- the strongest evidence we have for the existence of the dark matter does not come from rotation curves, but from CMB measurements instead!
-- the Planck team was able to do background subtraction very well because they had data from several channels: maps of synchro emission at radio frequencies and dust maps at FIR. Only 3% of the sky had to be interpolated.
-- Planck has the best dust maps of all time due to the previous point.
-- the mass map of the Universe from gravitational lensing measurements is incredible, and strongly correlates with cluster locations from the S-Z effect.
-- the spectral index n of the H-Z spectrum is not equal to 1 (this was news to me, I thought it should be close), but is near 0.96.
-- sigma_8 is less than 1 too (0.83, if I remember correctly)
-- there are issues w/ Planck-WMAP-SPT inter-calibration
-- the CMB is the edge of the visible Universe -- this is obvious, but I hadn't thought of it this way before.
-- there still are anomalies: the cold spot, differences of amount of structure between hemispheres, some structure that is compatible with a rotating Universe

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