The Cosmic Linear Anisotropy Solving System (CLASS) I: Overview

By Julien Lesgourgues. 2011

828 citations recorded by the source corpus.

The Cosmic Linear Anisotropy Solving System (CLASS) is a new accurate Boltzmann code, designed to offer a more user-friendly and flexible coding environment to cosmologists. CLASS is very structured, easy to modify, and offers a rigorous way to control the accuracy of output quantities. It is also incidentally a bit faster than other codes. In this overview, we present the general principles of CLASS and its basic structure. We insist on the friendliness and flexibility aspects, while accuracy, physical approximations and performances are discussed in a series of companion papers.

Subfields: Astronomy and Astrophysics, Statistical and Nonlinear Physics

View Paper: https://www.semanticscholar.org/paper/fed4dd90099b3f7c2fd39a7a98bbb4855315684a

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Citations in the corpus

The Atacama Cosmology Telescope: DR4 maps and cosmological parameters (2020, neutral): “This best-ﬁtting model has a χ 2 for ACT of 279 for 254 (260 26 The results were also reproduced with diﬀerent codes for theory predictions and sampling, i.e., using CLASS+Cobaya , CAMB+Cobaya and CAMB+CosmoSIS (Lesgourgues 2011; Lewis et al. 2000; Zuntz et al. 2015; Torrado & Lewis 2020).”
Constraining dark matter-neutrino interactions using the CMB and large-scale structure (2014, neutral): “[34] J. Lesgourgues (2011), 1104.2932.”
DESI 2024: reconstructing dark energy using crossing statistics with DESI DR1 BAO data (2024, methodology): “When including the measurements from the cosmic microwave background, we implement this parametrization using our modified version of the Boltzmann solver class [57, 58] that allows for an arbitrary redshift dependence of w ( z ).”
Maximal freedom at minimum cost: linear large-scale structure in general modifications of gravity (2014, methodology): “This is to allow for direct implementation of our formulation in codes as CAMB [13] or CLASS [14, 15].”
nbodykit: An Open-source, Massively Parallel Toolkit for Large-scale Structure (2017, methodology): “The underlying engine for these calculations is the CLASS Boltzmann solver (Blas et al. 2011; Lesgourgues 2011).”
Strongest model-independent bound on the lifetime of Dark Matter (2014, methodology): “We then describe their implementation in the public numerical code class1 [22, 23].”
Probing the theory of gravity with gravitational lensing of gravitational waves and galaxy surveys (2019, methodology): “(11) In this analysis, we have taken a linear bias model with the value of the bias parameter as bg = 1.6 (Anderson et al. 2012; Alam et al. 2017a; Desjacques et al. 2018) and the non-linear dark matter power spectrum from the numerical code CLASS (Blas et al. 2011; Lesgourgues 2011).”
The trouble with H0 (2016, methodology): “We have modified the publicly available CLASS code [38, 39] to implement this.”
Cosmological constraints on exotic injection of electromagnetic energy (2016, methodology): “5 routine of the Boltzmann code CLASS6 [11, 12] v2.”
The Cosmic Linear Anisotropy Solving System (CLASS). Part II: Approximation schemes (2011, methodology): “More exotic cases may require further approximations which can be introduced and discussed case-by-case ( CLASS is coded in such way that introducing a new approximation is as structured, codiﬁed and simple as introducing new species [6]).”
Cosmological parameters derived from the final Planck data release (PR4) (2023, methodology): “6 One can equally well use CLASS (Lesgourgues 2011; Blas et al. 2011) instead, except that the definition of θ∗ differs slightly between the two codes.”
Early dark energy does not restore cosmological concordance (2020, methodology): “We implement the EDE scenario as a modification to the publicly available Einstein-Boltzmann code CLASS (Lesgourgues (2011); Blas et al. (2011)).4 Our modified version, CLASS EDE, is publicly available (Hill et al. (2020)).5 CLASS EDE solves for the evolution of the scalar field perturbations…”
hi_class: Horndeski in the Cosmic Linear Anisotropy Solving System (2016, neutral): “; see [75]), with each module relying on the results generated by the previous ones.”
Constraint on neutrino masses from SDSS-III/BOSS Lyα forest and other cosmological probes (2014, methodology): “For this purpose, we use the CLASS7 solver [58, 59], embedded in the Monte Python code.”