DUNE: the Dark Universe Explorer

Réfrégier, Alexandre; Boulade, O.; Mellier, Y.; Milliard, B.; Pain, R.; Michaud, J.-B.; Safa, F.; Amara, Adam; Astier, P.; Barrelet, E.; Bertin, E.; Boulade, S.; Cara, C.; Claret, A.; Georges, L.; Grange, Robert; Guy, J.; Koeck, C.; Kroely, L.; Magneville, C.; Palanque-Delabrouille, N.; Regnault, Nicolas; Smadja, G.; Schimd, C.; Sun, Zeqing

doi:10.1117/12.672261

Cited by 25 publications

(16 citation statements)

References 15 publications

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“…Here we take the usual values of A = 2 and B = 1.5, so that C = 1.5/z 0 where z m = 0.9 and z 0 = z m /1.412 (z m median redshift; see, e.g., Refregier et al 2006;La Vacca & Colombo 2008, and references therein). This distribution is then considered within the limits of the redshift bins.…”

Section: Theorymentioning

confidence: 99%

Tomographic weak-lensing shear spectra from largeN-body and hydrodynamical simulations

Casarini

Bonometto

Borgani

et al. 2012

A&A

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Context. Forthcoming experiments will enable us to determine tomographic shear spectra at a high precision level. Most predictions about them have until now been based on algorithms yielding the expected linear and non-linear spectrum of density fluctuations. Even when simulations have been used, so-called Halofit predictions on fairly large scales have been needed. Aims. We wish to go beyond this limitation. Methods. We perform N-body and hydrodynamical simulations within a sufficiently large cosmological volume to allow a direct connection between simulations and linear spectra. While covering large length-scales, the simulation resolution is good enough to allow us to explore the high-harmonics of the cosmic shear (up to ∼ 50 000), well into the domain where baryon physics becomes important. We then compare shear spectra in the absence and in presence of various kinds of baryon physics, such as radiative cooling, star formation, and supernova feedback in the form of galactic winds. Results. We distinguish several typical properties of matter fluctuation spectra in the different simulations and test their impact on shear spectra. Conclusions. We compare our outputs with those obtainable using approximate expressions for non-linear spectra, and identify substantial discrepancies even between our results and those of purely N-body results. Our simulations and the treatment of their outputs however enable us, for the first time, to obtain shear results that are fully independent of any approximate expression, also in the high-range, where we need to incorporate a non-linear power spectrum of density perturbations and the effects of baryon physics. This will allow us to fully exploit the cosmological information contained in future high-sensitivity cosmic shear surveys, exploring the physics of cosmic shears via weak lensing measurements.

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Section: Theorymentioning

confidence: 99%

Tomographic weak-lensing shear spectra from largeN-body and hydrodynamical simulations

Casarini

Bonometto

Borgani

et al. 2012

A&A

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“…Finally, for the interpretation of the resulting data and the inference of cosmological parameters, an accurate theoretical model is needed. A thorough understanding of systematic effects in weak lensing will become particularly important with the advent of very large weak-lensing surveys such as CFHTLS 1 , KIDS 2 , Pan-STARRS 3 , and LSST 4 , or the planned Dark Energy Survey 5 , DUNE (Réfrégier et al 2006), and SNAP 6 . For these surveys, the statistical uncertainties will be very small, so the accuracy will be limited by the remaining systematics in the data reduction and theoretical modeling.…”

Section: Introductionmentioning

confidence: 99%

Ray-tracing through the Millennium Simulation: Born corrections and lens-lens coupling in cosmic shear and galaxy-galaxy lensing

Hilbert

Hartlap²,

White

et al. 2009

A&A

323

470

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Context. Weak-lensing surveys need accurate theoretical predictions for interpretation of their results and cosmological-parameter estimation. Aims. We study the accuracy of various approximations to cosmic shear and weak galaxy-galaxy lensing and investigate effects of Born corrections and lens-lens coupling. Methods. We use ray-tracing through the Millennium Simulation, a large N-body simulation of cosmic structure formation, to calculate various cosmic-shear and galaxy-galaxy-lensing statistics. We compare the results from ray-tracing to semi-analytic predictions. Results. (i) We confirm that the first-order approximation (i.e. neglecting lensing effects beyond first order in density fluctuations) provides an excellent fit to cosmic-shear power spectra as long as the actual matter power spectrum is used as input. Common fitting formulae, however, strongly underestimate the cosmic-shear power spectra (by >30% on scales > 10 000). Halo models provide a better fit to cosmic shear-power spectra, but there are still noticeable deviations (∼10%). (ii) Cosmic-shear B-modes, which are induced by Born corrections and lens-lens coupling, are at least three orders of magnitude smaller than cosmic-shear E-modes. Semianalytic extensions to the first-order approximation predict the right order of magnitude for the B-mode. Compared to the ray-tracing results, however, the semi-analytic predictions may differ by a factor two on small scales and also show a different scale dependence. (iii) The first-order approximation may under-or overestimate the galaxy-galaxy-lensing shear signal by several percent due to the neglect of magnification bias, which may lead to a correlation between the shear and the observed number density of lenses. Conclusions. (i) Current semi-analytic models need to be improved in order to match the degree of statistical accuracy expected for future weak-lensing surveys. (ii) Shear B-modes induced by corrections to the first-order approximation are not important for future cosmic-shear surveys. (iii) Magnification bias can be important for galaxy-galaxy-lensing surveys.

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“…Tereno et al 2005;Das & Spergel 2009) and considered as potentially the most powerful method to pin down the properties of dark energy (Hu 2002;Albrecht et al 2006;Peacock et al 2006 JDEM 4 , and Euclid 5 will produce deep imaging over large fractions of the sky and thereby yield unprecedented insight into the properties of dark matter, dark energy and gravitation (e.g. Takada & Jain 2004;Réfrégier et al 2004Réfrégier et al , 2006Kitching et al 2008a; Thomas et al 2009). …”

Section: Introductionmentioning

confidence: 99%

Simultaneous measurement of cosmology and intrinsic alignments using joint cosmic shear and galaxy number density correlations

Joachimi

Bridle

2010

A&A

195

303

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Aims. Cosmic shear is a powerful method to constrain cosmology, provided that any systematic effects are under control. The intrinsic alignment of galaxies is expected to severely bias parameter estimates if not taken into account. We explore the potential of a joint analysis of tomographic galaxy ellipticity, galaxy number density, and ellipticity-number density cross-correlations to simultaneously constrain cosmology and self-calibrate unknown intrinsic alignment and galaxy bias contributions. Methods. We treat intrinsic alignments and galaxy biasing as free functions of scale and redshift and marginalise over the resulting parameter sets. Constraints on cosmology are calculated by combining the likelihoods from all two-point correlations between galaxy ellipticity and galaxy number density. The information required for these calculations is already available in a standard cosmic shear data set. We include contributions to these functions from cosmic shear, intrinsic alignments, galaxy clustering and magnification effects. Results. In a Fisher matrix analysis we compare our constraints with those from cosmic shear alone in the absence of intrinsic alignments. For a potential future large area survey, such as Euclid, the extra information from the additional correlation functions can make up for the additional free parameters in the intrinsic alignment and galaxy bias terms, depending on the flexibility in the models. For example, the dark energy task force figure of merit is recovered even when more than 100 free parameters are marginalised over. We find that the redshift quality requirements are similar to those calculated in the absence of intrinsic alignments.

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DUNE: the Dark Universe Explorer

Cited by 25 publications

References 15 publications

Tomographic weak-lensing shear spectra from largeN-body and hydrodynamical simulations

Tomographic weak-lensing shear spectra from largeN-body and hydrodynamical simulations

Ray-tracing through the Millennium Simulation: Born corrections and lens-lens coupling in cosmic shear and galaxy-galaxy lensing

Simultaneous measurement of cosmology and intrinsic alignments using joint cosmic shear and galaxy number density correlations

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