Computer Science
Scientific paper
Mar 2002
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2002sgdh.conf...38b&link_type=abstract
THE SHAPES OF GALAXIES AND THEIR DARK HALOS. Proceedings of the Yale Cosmology Workshop. Held 28-30 May 2001 in New Haven, Conne
Computer Science
25
Galaxies, Gravitational Lensing
Scientific paper
The accurate measurement of galaxy ellipticities is vital for weak lensing studies, in particular cosmic shear. We describe a Bayesian approach to this problem in which galaxies are parameterized as sums of Gaussians, convolved with a PSF which is also a sum of Gaussians, following Kuijken (1999). We calculate the uncertainties in the output parameters using a Markov Chain Monte Carlo approach. We show that for a simple simulation, the ellipticity estimates do not give a biased result when averaged by statistical weight. It is shown that the uncertainties in the ellipticities are not increased by allowing freedom in the galaxy radial profile, or by allowing the photon shot noise level to be a free parameter. Finally we confirm the result of Kuijken (1999) that on changing the ellipticity of two point spread function Gaussian components, the reconstructed galaxy ellipticity is unbiased.
Bardeau Sebastien
Bridle Sarah L.
Gull Stephen F.
Kneib Jean Paul
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