[Triumf-seminars] TRIUMF Seminar today at 14:00

[postmaster at admin.triumf.ca]

Date/Time: Thu 2008-04-17 at 14:00

Location:  Auditorium          

Speaker:   Mark Halpern (UBC)

Title:     New results with WMAP five-year data set

Abstract: We have released maps and data for five years of observation of the cosmic microwave background with the Wilkinson Microwave Anisotropy Probe (WMAP) and I will review the main results in this talk. A simple 6 parameter cosmological model continues to be an excellent fit to the CMB data and to our data in conjunction with other astrophysical measurements.  In particular a running spectral index is not supported by the data, and constraints that the Universe is spatially flat have increased in precision.

Increased sensitivity and improvements in our understanding of the instrumental beam shape have allowed us to measure for the first time a cosmic neutrino background.  Neutrinos de-coupled from other matter earlier than photons did.  While they are expected to have a 2 Kelvin thermal distribution today, they comprised 10% of the energy density of the Universe at the epoch of photon de-coupling.  The data also allow tighter  constraints on the shape of the inflationary potential via the amplitude of a gravitational wave background new constraints on features of cosmic axions.

Stimulants available 15 minutes before the talk.

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