iCosmo: an interactive cosmology package

Réfrégier, Alexandre; Amara, Adam; Kitching, Thomas D.; Rassat, A.

doi:10.1051/0004-6361/200811112

Cited by 130 publications

(174 citation statements)

References 18 publications

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“…Jeong & Komatsu 2006;Nishimichi et al 2007Nishimichi et al , 2009Crocce & Scoccimarro 2008;Matsubara 2008;Taruya et al 2009;Sato & Matsubara 2011;Valageas & Nishimichi 2011a,b). In the weak-lensing context, this higher accuracy could also be useful for the analysis of future observations such as the Euclid mission (Refregier et al 2010).…”

Section: Convergence Power Spectrummentioning

confidence: 98%

“…Thus, weak lensing has the highest potential to constrain the properties of dark energy among other cosmological observations, if the systematic errors are well kept under control (Albrecht et al 2006). To address questions about the nature of dark energy and the properties of gravity on cosmological scales, various surveys are planned, such as the Hyper Suprime-Cam Weak Lensing Survey (Miyazaki et al 2006) 1 , the Dark Energy Survey (DES) 2 , the Large Synoptic Survey Telescope (LSST) 3 , Euclid (Refregier et al 2010) 4 , and the Wide-Field Infrared Survey Telescope (WFIRST) 5 .…”

Section: Introductionmentioning

confidence: 99%

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Modeling of weak-lensing statistics

Valageas

Sato

Nishimichi

2012

A&A

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Aims. We investigate the performance of an analytic model of the 3D matter distribution, which combines perturbation theory with halo models, for weak-lensing statistics. Methods. We compare our predictions for the weak-lensing convergence power spectrum and bispectrum with numerical simulations and fitting formulas proposed in previous works. Results. We find that this model provides better agreement with simulations than published fitting formulas. This shows that building on systematic and physically motivated models is a promising approach. Moreover, this makes explicit the link between the weaklensing statistics and the underlying properties of the 3D matter distribution, as a function of scale . Thus, we obtain the contributions to the lensing power spectrum and bispectrum that arise from perturbative terms (complete up to one-loop) and nonperturbative terms (e.g., "1-halo" term). Finally, we show that this approach recovers the dependence on cosmology (for realistic scenarios).

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Section: Convergence Power Spectrummentioning

confidence: 98%

Section: Introductionmentioning

confidence: 99%

Modeling of weak-lensing statistics

Valageas

Sato

Nishimichi

2012

A&A

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“…We want to keep our analysis as general as possible, not having to assume such a strong prior on σ 8 . Following the icosmo code (Refregier et al 2008) we instead interpolate the non-linear corrections from Smith et al (2003) between the cases of a ΛCDM cosmology (w = −1) and an OCDM cosmology, acting as a dark energy with w = −1/3. This is achieved by replacing the parameter f = Ω Λ /(1 − Ω m ) in the halo model fitting function (Smith et al 2003).…”

Section: Non-linear Power Spectrum Correctionsmentioning

confidence: 99%

Evidence of the accelerated expansion of the Universe from weak lensing tomography with COSMOS

Schrabback

Hartlap

Joachimi

et al. 2010

A&A

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We present a comprehensive analysis of weak gravitational lensing by large-scale structure in the Hubble Space Telescope Cosmic Evolution Survey (COSMOS), in which we combine space-based galaxy shape measurements with ground-based photometric redshifts to study the redshift dependence of the lensing signal and constrain cosmological parameters. After applying our weak lensingoptimized data reduction, principal-component interpolation for the spatially, and temporally varying ACS point-spread function, and improved modelling of charge-transfer inefficiency, we measured a lensing signal that is consistent with pure gravitational modes and no significant shape systematics. We carefully estimated the statistical uncertainty from simulated COSMOS-like fields obtained from ray-tracing through the Millennium Simulation, including the full non-Gaussian sampling variance. We tested our lensing pipeline on simulated space-based data, recalibrated non-linear power spectrum corrections using the ray-tracing analysis, employed photometric redshift information to reduce potential contamination by intrinsic galaxy alignments, and marginalized over systematic uncertainties. We find that the weak lensing signal scales with redshift as expected from general relativity for a concordance ΛCDM cosmology, including the full cross-correlations between different redshift bins. Assuming a flat ΛCDM cosmology, we measure σ 8 (Ω m /0.3) 0.51 = 0.75 ± 0.08 from lensing, in perfect agreement with WMAP-5, yielding joint constraints Ω m = 0.266 +0.025 −0.023 , σ 8 = 0.802 +0.028 −0.029 (all 68.3% conf.). Dropping the assumption of flatness and using priors from the HST Key Project and Big-Bang nucleosynthesis only, we find a negative deceleration parameter q 0 at 94.3% confidence from the tomographic lensing analysis, providing independent evidence of the accelerated expansion of the Universe. For a flat wCDM cosmology and prior w ∈ [−2, 0], we obtain w < −0.41 (90% conf.). Our dark energy constraints are still relatively weak solely due to the limited area of COSMOS. However, they provide an important demonstration of the usefulness of tomographic weak lensing measurements from space.

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“…The SFB calculations use the discrete spherical Bessel transform (DSBT) presented in Lanusse et al (2012) and the authors are grateful to François Lanusse for help implementing this. We extended iCosmo 2 software for our calculations (Refregier et al 2011). This research is in part supported by the Swiss National Science Foundation (SNSF).…”

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confidence: 99%

3D spherical analysis of baryon acoustic oscillations

Rassat

Réfrégier

2012

A&A

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Context. Baryon acoustic oscillations (BAOs) are oscillatory features in the galaxy power spectrum which are used as a standard rod to measure the cosmological expansion. These have been studied in Cartesian space (Fourier or real space) or in spherical harmonic space in thin shells. Aims. Future wide-field surveys will cover both wide and deep regions of the sky and thus require a simultaneous treatment of the spherical sky and of an extended radial coverage. The spherical Fourier-Bessel (SFB) decomposition is a natural basis for the analysis of fields in this geometry and facilitates the combination of BAO surveys with other cosmological probes readily described in this basis. In this paper, we present a new way to analyse BAOs by studying the BAO wiggles from the SFB power spectrum. Methods. In SFB space, the power spectrum generally has both a radial (k) and tangential ( ) dependence and so do the BAOs. In the deep survey limit and ignoring evolution, the SFB power spectrum is purely radial and reduces to the Cartesian Fourier power spectrum. In the opposite limit of a thin shell, all the information is contained in the tangential modes described by the 2D spherical harmonic power spectrum. Results. We find that the radialisation of the SFB power spectrum is still a good approximation even when considering an evolving and biased galaxy field with a finite selection function. This effect can be observed by all-sky surveys with depths comparable to current surveys. We also find that the BAOs radialise more rapidly than the full SFB power spectrum. Conclusions. Our results suggest the first peak of the BAOs in SFB space becomes radial out to ∼ 10 for all-sky surveys with the same depth as SDSS or 2dF, and out to ∼ 70 for an all-sky stage IV survey. Subsequent BAO peaks will also become radial, but for shallow surveys these may be in the non-linear regime. For modes that have become radial, measurements at different 's are useful in practice to reduce measurement errors.

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iCosmo: an interactive cosmology package

Cited by 130 publications

References 18 publications

Modeling of weak-lensing statistics

Modeling of weak-lensing statistics

Evidence of the accelerated expansion of the Universe from weak lensing tomography with COSMOS

3D spherical analysis of baryon acoustic oscillations

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