The Cosmic Linear Anisotropy Solving System (CLASS) IV: efficient implementation of non-cold relics

By Julien Lesgourgues, Thomas Tram. 2011

328 citations recorded by the source corpus.

We present a new flexible, fast and accurate way to implement massive neutrinos, warm dark matter and any other non-cold dark matter relics in Boltzmann codes. For whatever analytical or numerical form of the phase-space distribution function, the optimal sampling in momentum space compatible with a given level of accuracy is automatically found by comparing quadrature methods. The perturbation integration is made even faster by switching to an approximate viscous fluid description inside the Hubble radius, which differs from previous approximations discussed in the literature. When adding one massive neutrino to the minimal cosmological model, CLASS becomes just 1.5 times slower, instead of about 5 times in other codes (for fixed accuracy requirements). We illustrate the flexibility of our approach by considering a few examples of standard or non-standard neutrinos, as well as warm dark matter models.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/2839943bec5e8aa18733e59c9f524dee4c98e5ff

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Citations in the corpus

The Cosmic Linear Anisotropy Solving System (CLASS) I: Overview (2011, methodology): “…logic is used by the code for deﬁning the discrete times at which the source functions S ( k, τ ) (needed to compute the observable spectra) are sampled; or for deﬁning the momentum bins in which the phase-space distribution of each massive neutrinos and other non-cold relics are calculated [14].”
The Cosmic Linear Anisotropy Solving System (CLASS). Part II: Approximation schemes (2011, background): “In a companion paper [7], we already discuss the approximation speciﬁc to massive neutrinos and non-cold dark matter relics.”
KiDS-450: The tomographic weak lensing power spectrum and constraints on cosmological parameters (2017, methodology): “Therefore, we use here the HALOFIT algorithm within CLASS (including the Takahashi et al. 2012 recalibration and massive neutrino modelling on non-linear scales by Bird et al. 2012) and add the baryon feedback model through equation (19) instead.”
KiDS+VIKING-450: Cosmic shear tomography with optical and infrared data (2018, methodology): “The total matter power spectrum is estimated with the Boltzmann-code class (Blas et al. 2011; Audren & Lesgourgues 2011; Lesgourgues & Tram 2011) with non-linear corrections from HMCode (Mead et al. 2015).”
Neutrino Mass from Cosmology (2012, methodology): “However, nowadays the analyses are performed using the matter power spectra calculated by Boltzmann codes such as camb [54] or class [55], that solve numerically the evolution of the cosmological perturbations.”
An efficient implementation of massive neutrinos in non-linear structure formation simulations (2012, background): “This effect has long been understood in the linear regime (Bond et al. 1980; Bond & Szalay 1983; Ma & Bertschinger 1995; Lesgourgues & Pastor 2006, and references therein), and is implemented in all modern Boltzmann codes (see for example Lewis & Challinor 2002; Lesgourgues & Tram 2011).”
hi_class: Horndeski in the Cosmic Linear Anisotropy Solving System (2016, methodology): “Several extensions of the ΛCDM concordance scenario, such as massive neutrinos, warm dark mater, curvature [71–73], but also quintessence and perfect-fluid dark energy, have already been implemented in a manner compatible with the CLASS principles.”
Massive neutrinos and the non‐linear matter power spectrum (2011, methodology): “…O ] 1 3 Ja ory, this effect is relatively straightforward to quantify with numerical simulations or approximate schemes (e.g. Bond et al. (1980); Zeldovich et al. (1980); Ma & Bertschinger (1994); Valdarnini et al. (1998)) using standard Boltzmann codes (Lewis et al. 2000; Lesgourgues & Tram 2011).”