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Article Dans Une Revue Astronomy and Astrophysics - A&A Année : 2003

Measuring Omega0 with higher-order quasar-galaxy correlations induced by weak lensing

Résumé

Via the magnification bias, gravitational lensing by large-scale structures causes angular cross-correlations between distant quasars and foreground galaxies on angular scales of arcminutes and above. We investigate the three-point cross-correlation between quasars and galaxy pairs measurable via the second moment of the galaxy counts around quasars and show that it reaches the level of a few per cent on angular scales near one arcminute. Combining two- and three-point correlations, a skewness parameter can be defined which is shown to be virtually independent of the shape and normalisation of the dark-matter power spectrum. If the galaxy bias is linear and deterministic, the skewness depends on the cosmic matter density parameter Omega0 only; otherwise, it can be used to probe the non-linearity and stochasticity of the bias. We finally estimate the signal-to-noise ratio of a skewness determination and find that a sample of about twenty thousand distant quasars e.g. from the Sloan Digital Sky Survey should suffice for a direct measurement of Omega0.
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hal-04111191 , version 1 (09-06-2023)

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B. Ménard, M. Bartelmann, Y. Mellier. Measuring Omega0 with higher-order quasar-galaxy correlations induced by weak lensing. Astronomy and Astrophysics - A&A, 2003, 409, pp.411-421. ⟨10.1051/0004-6361:20031095⟩. ⟨hal-04111191⟩
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