CosmoBit: a GAMBIT module for computing cosmological observables and likelihoods

Abstract

We introduce CosmoBit, a module within the open-source GAMBIT software framework for exploring connections between cosmology and particle physics with joint global fits. CosmoBit provides a flexible framework for studying various scenarios beyond ΛCDM, such as models of inflation, modifications of the effective number of relativistic degrees of freedom, exotic energy injection from annihilating or decaying dark matter, and variations of the properties of elementary particles such as neutrino masses and the lifetime of the neutron. Many observables and likelihoods in CosmoBit are computed via interfaces to AlterBBN, CLASS, DarkAges, MontePython, MultiModeCode, and plc. This makes it possible to apply a wide range of constraints from large-scale structure, Type Ia supernovae, Big Bang Nucleosynthesis and the cosmic microwave background. Parameter scans can be performed using the many different statistical sampling algorithms available within the GAMBIT framework, and results can be combined with calculations from other GAMBIT modules focused on particle physics and dark matter. We include extensive validation plots and a first application to scenarios with non-standard relativistic degrees of freedom and neutrino temperature, showing that the corresponding constraint on the sum of neutrino masses is much weaker than in the standard scenario.

First direct neutrino-mass measurement with sub-eV sensitivity

“…Combined with the first campaign we set an improved upper limit of m ν < 0.8 eV (90 % CL). We therefore have narrowed down the allowed range of quasi-degenerate neutrino-mass models and we have provided model-independent information about the neutrino mass, which allows the testing of non-standard cosmological models 64,65 . Fig.…”

Thermal WIMPs and the scale of new physics: global fits of Dirac dark matter effective field theories

“…The first part of this calculation has been automated within DarkSUSY and is accessible via DarkBit. The second part relies on DarkAges [147] (which is part of the ExoCLASS branch of CLASS) and is accessible via CosmoBit [54], see Appendix C for further details. 10 As the Planck collaboration only quotes the 95% credible interval for p ann [98], the remaining challenge is to obtain a likelihood for p ann from cosmological data.…”

“…Second, we consider the most recent constraints on DM annihilations using gamma rays and the Cosmic Microwave Background (CMB). To include the latter, we employ the recently released GAMBIT module CosmoBit [54], which uses detailed spectra to calculate effective functions for the efficiency of the injected energy deposition and obtain constraints on the DM annihilation cross-section while varying cosmological parameters. For the calculation of annihilation cross-sections we make use of the new GAMBIT Universal Model Machine (GUM) [55,56] to automatically generate the relevant code based on the EFT Lagrangian.…”

BSM Developments and Tools

“…Nevertheless, the indisputable leader of BSM inference studies is the GAMBIT tool [16,60]. GAMBIT contains a huge library of likelihoods and observables for collider physics [15], dark matter [43], flavour [61], precision observables [62], neutrino physics [63] and cosmology [64], as well as an extensive database of models and sampling strategies, both frequentist and Bayesian [65]. GAMBIT has been employed in studies of a large variety of BSM modes, including SUSY models [66][67][68], Higgs-portal DM models [44,69,70], EFT DM models [71], axion and axion-like particle models [72,73], models with right-handed neutrinos [63], fits of neutral flavour anomalies [74] and cosmological fits of neutrino masses [75].…”