The Cosmic Linear Anisotropy Solving System (CLASS).
 Part II: Approximation schemes

Blas, Diego; Lesgourgues, Julien; Tram, Thomas

doi:10.1088/1475-7516/2011/07/034

Cited by 2,070 publications

(1,581 citation statements)

References 27 publications

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“…at high q would expect Gauss-Laguerre point sampling to be nearly optimal [43] At late times further speedups are possible. For highly sub-horizon perturbation kτ 1 (as for massless neutrinos), and once significantly non-relativistic, l max can be reduced down to 2 or 3 [11] Once the neutrinos become very nonrelativistic we can evolve velocity-integrated equations (i.e. a truncated fluid hierarchy); this is described in detail in Ref.…”

Section: Resultsmentioning

confidence: 99%

“…However these studies have focused on spatially-flat or otherwise restricted models. Recent new approximations and coding development aimed towards Planck data analysis have led to faster high accuracy calculations, and accuracy settings have been adjusted to allow efficient calculation of power spectra at the 0.1% accuracy level [10][11][12]. As the code has developed the approximations and accuracy settings have been extensively tested as part of routine development, and we shall not labour the reader by giving an extensive presentation here.…”

Section: Introductionmentioning

confidence: 99%

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CMB power spectrum parameter degeneracies in the era of precision cosmology

Howlett

Lewis

Hall

et al. 2012

J. Cosmol. Astropart. Phys.

459

371

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Cosmological parameter constraints from the CMB power spectra alone suffer several well-known degeneracies. These degeneracies can be broken by numerical artefacts and also a variety of physical effects that become quantitatively important with high-accuracy data e.g. from the Planck satellite. We study degeneracies in models with flat and non-flat spatial sections, non-trivial dark energy and massive neutrinos, and investigate the importance of various physical degeneracy-breaking effects. We test the camb power spectrum code for numerical accuracy, and demonstrate that the numerical calculations are accurate enough for degeneracies to be broken mainly by true physical effects (the integrated Sachs-Wolfe effect, CMB lensing and geometrical and other effects through recombination) rather than numerical artefacts. We quantify the impact of CMB lensing on the power spectra, which inevitably provides degeneracy-breaking information even without using information in the non-Gaussianity. Finally we check the numerical accuracy of sample-based parameter constraints using camb and CosmoMC. In an appendix we document recent changes to camb's numerical treatment of massive neutrino perturbations, which are tested along with other recent improvements by our degeneracy exploration results.

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Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

CMB power spectrum parameter degeneracies in the era of precision cosmology

Howlett

Lewis

Hall

et al. 2012

J. Cosmol. Astropart. Phys.

459

371

View full text Add to dashboard Cite

show abstract

“…12 affects the visibility function for CMB anisotropies, and as a consequence the angular power spectra of temperature and polarization fluctuations. We have incorporated the modified hyrec into the Boltzmann code class [46]. We show in Fig.…”

Section: Effect On Cmb Anisotropy Power Spectramentioning

confidence: 99%

Cosmic microwave background limits on accreting primordial black holes

2017

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Interest in the idea that primordial black holes (PBHs) might comprise some or all of the dark matter has recently been rekindled following LIGO's first direct detection of a binary-black-hole merger. Here we revisit the effect of accreting PBHs on the cosmic microwave background (CMB) frequency spectrum and angular temperature/polarization power spectra. We compute the accretion rate and luminosity of PBHs, accounting for their suppression by Compton drag and Compton cooling by CMB photons. We estimate the gas temperature near the Schwarzschild radius, and hence the free-free luminosity, accounting for the cooling resulting from collisional ionization when the background gas is mostly neutral. We account approximately for the velocities of PBHs with respect to the background gas. We provide a simple analytic estimate of the efficiency of energy deposition in the plasma. We find that the spectral distortions generated by accreting PBHs are too small to be detected by FIRAS, as well as by future experiments now being considered. We analyze Planck CMB temperature and polarization data and find, under our most conservative hypotheses, and at the order-of-magnitude level, that they rule out PBHs with masses 10 2 M as the dominant component of dark matter.

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“…We modify the publicly available Boltzmann code class [54] and include this ultralight scalar field as a new species, that will assume the role of dark matter. Now, we summarize the key changes in the code and the evolution scheme chosen for the scalar field.…”

Section: Numerical Evolution and Constraintsmentioning

confidence: 99%

Constraints on anharmonic corrections of fuzzy dark matter

Cembranos

Maroto

Jareño

et al. 2018

J. High Energ. Phys.

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The cold dark matter (CDM) scenario has proved successful in cosmology. However, we lack a fundamental understanding of its microscopic nature. Moreover, the apparent disagreement between CDM predictions and subgalactic-structure observations has prompted the debate about its behaviour at small scales. These problems could be alleviated if the dark matter is composed of ultralight fields m ∼ 10 −22 eV, usually known as fuzzy dark matter (FDM). Some specific models, with axion-like potentials, have been thoroughly studied and are collectively referred to as ultralight axions (ULAs) or axion-like particles (ALPs). In this work we consider anharmonic corrections to the mass term coming from a repulsive quartic self-interaction. Whenever this anharmonic term dominates, the field behaves as radiation instead of cold matter, modifying the time of matter-radiation equality. Additionally, even for high masses, i.e. masses that reproduce the cold matter behaviour, the presence of anharmonic terms introduce a cut-off in the matter power spectrum through its contribution to the sound speed. We analyze the model and derive constraints using a modified version of class and comparing with CMB and large-scale structure data.

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The Cosmic Linear Anisotropy Solving System (CLASS). Part II: Approximation schemes

Cited by 2,070 publications

References 27 publications

CMB power spectrum parameter degeneracies in the era of precision cosmology

CMB power spectrum parameter degeneracies in the era of precision cosmology

Cosmic microwave background limits on accreting primordial black holes

Constraints on anharmonic corrections of fuzzy dark matter

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