AAS 201st Meeting, January, 2003
Session 80. Gravitational Lenses
Poster, Wednesday, January 8, 2003, 9:20am-6:30pm, Exhibit Hall AB

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[80.11] Calibration Issues for Cosmic Shear Measurements

C.M. Hirata, U. Seljak (Princeton Univ.)

Control of calibration errors in shear estimators will be essential to cosmic shear measurements that aim to constrain cosmological parameters to unprecedented accuracy. Such errors can affect the normalization of the cosmic shear power spectrum and, if they are dependent on angular diameter or other factors that correlate with redshift, can affect attempts to measure the evolution of the power spectrum and the equation of state of the dark energy. We compare methods for removing the circularizing effect of seeing on a galaxy’s image. We also draw attention to a previously unrecognized calibration error resulting from a selection bias: since most galaxy detection algorithms preferentially select circular galaxies, galaxies intrinsically aligned orthogonal to the cosmic shear are more likely to be observed, resulting in an underestimate of the shear.

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Bulletin of the American Astronomical Society, 34, #4
© 2002. The American Astronomical Soceity.