Le bébé, l’intime et l’étrange

Mellier, Denis; Rochette-Guglielmi, Joëlle

doi:10.3917/eres.prat.1998.01

Cited by 7 publications

(6 citation statements)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…have made a convincing detection of coherent shear due to a supercluster. Several observational efforts to measure weak lensing that use wide field CCD detectors are currently underway (see Mellier 1998 for a review).…”

Section: Introductionmentioning

confidence: 99%

Ray‐tracing Simulations of Weak Lensing by Large‐Scale Structure

Jain

Seljak

White

2000

ApJ

302

478

View full text Add to dashboard Cite

We investigate weak lensing by large-scale structure using ray tracing through N-body simulations. Photon trajectories are followed through high resolution simulations of structure formation to make simulated maps of shear and convergence on the sky. Tests with varying numerical parameters are used to calibrate the accuracy of computed lensing statistics on angular scales from ∼ 1 arcminute to a few degrees. Various aspects of the weak lensing approximation are also tested. We show that the non-scalar component of the shear generated by the multiple deflections is small. For fields a few degrees on a side the shear power spectrum is almost entirely in the nonlinear regime and agrees well with nonlinear analytical predictions. Sampling fluctuations in power spectrum estimates are investigated by comparing several ray tracing realizations of a given model. For survey areas smaller than a degree on a side the main source of scatter is nonlinear coupling to modes larger than the survey. We develop a method which uses this effect to estimate Ω m from the scatter in power spectrum estimates for subregions of a larger survey. We show that the power spectrum can be measured accurately on scales corresponding to 1 − 10 h −1 Mpc with realistic number densities of source galaxies with large intrinsic ellipticities. Non-Gaussian features in the one point distribution function of the weak lensing convergence (reconstructed from the shear) are also sensitive to Ω m . We suggest several techniques for estimating Ω m in the presence of noise and compare their statistical power, robustness and simplicity. With realistic number densities of source galaxies Ω m can be determined to within 0.1 − 0.2 from a deep survey of several square degrees.

show abstract

Section: Introductionmentioning

confidence: 99%

Ray‐tracing Simulations of Weak Lensing by Large‐Scale Structure

Jain

Seljak

White

2000

ApJ

302

478

View full text Add to dashboard Cite

show abstract

“…Therefore, unless unknown important systematics have been disregarded, we now have the first direct observational evidences that high mass-density peaks have generated massive clusters of galaxies at redshift 1. These promising results are corroborated by weak lensing studies around radio sources and quasars (Mellier 1998).…”

Section: Clusters From Weak Lensing Analysismentioning

confidence: 55%

“…Each panel can be found in the universe so this kind of template of lens features can be helpful for the understanding of the lens modeling. This has been extensively used, in particular on HST images (see , Natarajan & Kneib 1997, Mellier 1998 and references therein).…”

Section: The Singular Isothermal Spherementioning

confidence: 99%

“…Spectroscopic surveys and photometric redshifts allows to model the redshift distribution of galaxies. The procedure itself requires technical analysis of the data (see Mellier 1998 for the technical issues) and theoretical relations provided by gravitational lensing theory. The crucial points are the relations between shear, mass density and geometry of the lensed galaxies.…”

Section: Clusters From Weak Lensing Analysismentioning

confidence: 99%

“…However, in order to avoid self-duplications, I will only address some aspects about the mass determination from gravitational lensing studies. The other topics more detailed presentations (namely, distant galaxies, cosmological parameters, lensing on the CMB) or more detailed presentations can be found in Bernardeau (this proceedings), Blandford & Narayan (1992), , Mellier (1998Mellier ( , 1999, Refsdal & Surdej (1994) and obviously in the textbook written by Schneider, Ehlers & Falco (1992). The microlensing experiments will be also presented elsewhere (Rich, this proceedings).…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations