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Astronomy Tea Talks at Caltech

Mondays, Robinson 106
Tea:  4.00pm
Talk: 4.15pm

Organised by:

2007 - 2008 season:
5 May 2008 Joël Bergé (JPL)

"Combined analysis of weak lensing and X-ray blind surveys"


Weak gravitational lensing, the coherent distorsion of distant
galaxies by intervening dark matter, has proven to be a unique
cosmological probe. It is sensitive to mass only, and hence it
provides a direct measurement of the mass along the line of sight. In
particular, it allows one to weigh galaxy clusters independently of
their physical state. Combined to other wavelengths observations,
such as X-ray data, it appears as a unique method to calibrate galaxy
clusters' scaling relations.
I will present the combined analysis of weak lensing and X-ray data
in the CFHTLS Deep / XMM surveys. I will show a mass map of the
CFHTLS D1 field, obtained using the shapelets shear measurement
technique. I will then discuss the weak lensing selection function
for clusters of galaxies. Counting clusters as a function of their
signal-to-noise ratio allows us to estimate the amplitude of density
fluctuations sigma8. I will show how we can weigh galaxy clusters and
measure their mass-temperature (M-T) relation. Finally, I will
discuss the best observational strategy one should follow to measure
sigma8 and the M-T relation normalization when combining weak lensing and
X-ray blind surveys.
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Last modified on 30th Apr 2008 by Johan Richard.  

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