2015/06/24 by Bjoern Malte Schaefer, Schaefer, Bjoern Malte, Philipp M. Merkel +1
Earth and Planetary Sciences · Physics and Astronomy · #Geophysics and Gravity Measurements #Pulsars and Gravitational Waves Research #Galaxies: Formation, Evolution, Phenomena
paper · pdf · doi:10.48550/arxiv.1506.07366
Subject of this paper are intrinsic ellipticity correlations between\ngalaxies, their statistical properties, their observability with future surveys\nand their interference with weak gravitational lensing measurements. Using an\nangular momentum-based, quadratic intrinsic alignment model we derive\ncorrelation functions of the ellipticity components and project them to yield\nthe four non-zero angular ellipticity spectra C^\εE(\ℓ),\nC^\εB(\ℓ), C^\εC(\ℓ) and C^\εS(\ℓ) in their\ngeneralisation to tomographic surveys. For a Euclid-like survey, these spectra\nwould have amplitudes smaller than the weak lensing effect on nonlinear\nstructures, but would constitute an important systematic. Computing estimation\nbiases for cosmological parameters derived from an alignment-contaminated\nsurvey suggests biases of +5\σw for the dark energy equation of state\nparameter w, -20\σ\Ωm for the matter density \Ωm and\n-12\σ\σ8 for the spectrum normalisation \σ8. Intrinsic\nalignments yield a signal which is easily observable with a survey similar to\nEuclid: While not independent, significances for estimates of each of the four\nspectra reach values of tens of \σ if weak lensing and shape noise are\nconsidered as noise sources, which suggests relative uncertainties on alignment\nparameters at the percent level.\n