Full-sky weak-lensing simulation with 70 billion particles

Teyssier, Romain; Pires, S.; Prunet, S.; Aubert, Dominique; Pichon, Christophe; Amara, Adam; Benabed, K.; Colombi, S.; Réfrégier, Alexandre; Starck, Jean-Luc

doi:10.1051/0004-6361/200810657

Cited by 140 publications

(167 citation statements)

References 26 publications

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“…Ray-tracing is affected by similar problems as the simulation of the lens effect on CMB maps, i.e., difficulties in accurately resampling a vector field on the sphere. Current state-of-the-art ray-tracing algorithms, such as described by Teyssier et al (2009), could be made more accurate by using the technique described here.…”

Section: Simulation Proceduresmentioning

confidence: 99%

The pre-launchPlanckSky Model: a model of sky emission at submillimetre to centimetre wavelengths

Delabrouille

Betoule

Melin

et al. 2013

A&A

Self Cite

208

231

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We present the Planck Sky Model (PSM), a parametric model for generating all-sky, few arcminute resolution maps of sky emission at submillimetre to centimetre wavelengths, in both intensity and polarisation. Several options are implemented to model the cosmic microwave background, Galactic diffuse emission (synchrotron, free-free, thermal and spinning dust, CO lines), Galactic H ii regions, extragalactic radio sources, dusty galaxies, and thermal and kinetic Sunyaev-Zeldovich signals from clusters of galaxies. Each component is simulated by means of educated interpolations/extrapolations of data sets available at the time of the launch of the Planck mission, complemented by state-of-the-art models of the emission. Distinctive features of the simulations are spatially varying spectral properties of synchrotron and dust; different spectral parameters for each point source; modelling of the clustering properties of extragalactic sources and of the power spectrum of fluctuations in the cosmic infrared background. The PSM enables the production of random realisations of the sky emission, constrained to match observational data within their uncertainties. It is implemented in a software package that is regularly updated with incoming information from observations. The model is expected to serve as a useful tool for optimising planned microwave and sub-millimetre surveys and testing data processing and analysis pipelines. It is, in particular, used to develop and validate data analysis pipelines within the Planck collaboration. A version of the software that can be used for simulating the observations for a variety of experiments is made available on a dedicated website.

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Section: Simulation Proceduresmentioning

confidence: 99%

The pre-launchPlanckSky Model: a model of sky emission at submillimetre to centimetre wavelengths

Delabrouille

Betoule

Melin

et al. 2013

A&A

Self Cite

208

231

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“…Numerical simulations do not easily allow such a detailed analysis; however, in order to validate our approach, we must check whether it agrees with estimates from simulations, wherever a comparison is possible. We use the high-resolution full-sky Horizon simulation (Teyssier et al 2009), based on the WMAP3 cosmology (Spergel et al 2007). This is a 68.7 billion particle N-body simulation, featuring more than 140 billion cells in the AMR grid of the RAMSES code (Teyssier 2002).…”

Section: Numerical Simulationsmentioning

confidence: 99%

Covariance matrices for halo number counts and correlation functions

Valageas

Clerc

Pacaud

et al. 2011

A&A

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Aims. We study the mean number counts and two-point correlation functions, along with their covariance matrices, of cosmological surveys such as for clusters. In particular, we consider correlation functions averaged over finite redshift intervals, which are well suited to cluster surveys or populations of rare objects, where one needs to integrate over nonzero redshift bins to accumulate enough statistics. Methods. We develop an analytical formalism to obtain explicit expressions of all contributions to these means and covariance matrices, taking into account both shot-noise and sample-variance effects. We compute low-order as well as high-order (including non-Gaussian) terms. Results. We derive expressions for the number counts per redshift bins both for the general case and for the small window approximation. We estimate the range of validity of Limber's approximation and the amount of correlation between different redshift bins. We also obtain explicit expressions for the integrated 3D correlation function and the 2D angular correlation. We compare the relative importance of shot-noise and sample-variance contributions, and of low-order and high-order terms. We check the validity of our analytical results through a comparison with the Horizon full-sky numerical simulations, and we obtain forecasts for several future cluster surveys.

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“…The abundance of light elements can be computed, and their values agree with observations, with the possible exception of 7 Li (see [29] for a recent review). Moreover, numerical simulations [30] of large scale structure formation based on what we believe to be the relevant initial conditions, as deduced from the properties of the CMBR, reproduce well the observed features of the actual distribution: at first sight, the standard hot big bang model successfully provides a description of the Universe back to a fraction of a second after its birth until today with amazing precision; it is hard to overestimate the success that such a model represents in a science that a century ago did not exist.…”

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confidence: 99%

A critical review of classical bouncing cosmologies

2015

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Given the proliferation of bouncing models in recent years, we gather and critically assess these proposals in a comprehensive review. The PLANCK data shows an unmistakably red, quasi scaleinvariant, purely adiabatic primordial power spectrum and no primary non-Gaussianities. While these observations are consistent with inflationary predictions, bouncing cosmologies aspire to provide an alternative framework to explain them. Such models face many problems, both of the purely theoretical kind, such as the necessity of violating the NEC and instabilities, and at the cosmological application level, as exemplified by the possible presence of shear. We provide a pedagogical introduction to these problems and also assess the fitness of different proposals with respect to the data. For example, many models predict a slightly blue spectrum and must be fine-tuned to generate a red spectral index; as a side effect, large non-Gaussianities often result.We highlight several promising attempts to violate the NEC without introducing dangerous instabilities at the classical and/or quantum level. If primordial gravitational waves are observed, certain bouncing cosmologies, such as the cyclic scenario, are in trouble, while others remain valid. We conclude that, while most bouncing cosmologies are far from providing an alternative to the inflationary paradigm, a handful of interesting proposals have surfaced, which warrant further research. The constraints and lessons learned as laid out in this review might guide future research.

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Full-sky weak-lensing simulation with 70 billion particles

Cited by 140 publications

References 26 publications

The pre-launchPlanckSky Model: a model of sky emission at submillimetre to centimetre wavelengths

The pre-launchPlanckSky Model: a model of sky emission at submillimetre to centimetre wavelengths

Covariance matrices for halo number counts and correlation functions

A critical review of classical bouncing cosmologies

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