Interacting dark sector and precision cosmology
- 1 January 2018
- journal article
- research article
- Published by IOP Publishing in Journal of Cosmology and Astroparticle Physics
- Vol. 2018 (01), 008
- https://doi.org/10.1088/1475-7516/2018/01/008
Abstract
We consider a recently proposed model in which dark matter interacts with a thermal background of dark radiation. Dark radiation consists of relativistic degrees of freedom which allow larger values of the expansion rate of the universe today to be consistent with CMB data (H0-problem). Scattering between dark matter and radiation suppresses the matter power spectrum at small scales and can explain the apparent discrepancies between ΛCDM predictions of the matter power spectrum and direct measurements of Large Scale Structure LSS (σ8-problem). We go beyond previous work in two ways: 1. we enlarge the parameter space of our previous model and allow for an arbitrary fraction of the dark matter to be interacting and 2. we update the data sets used in our fits, most importantly we include LSS data with full k-dependence to explore the sensitivity of current data to the shape of the matter power spectrum. We find that LSS data prefer models with overall suppressed matter clustering due to dark matter - dark radiation interactions over ΛCDM at 3–4 σ. However recent weak lensing measurements of the power spectrum are not yet precise enough to clearly distinguish two limits of the model with different predicted shapes for the linear matter power spectrum. In two appendices we give a derivation of the coupled dark matter and dark radiation perturbation equations from the Boltzmann equation in order to clarify a confusion in the recent literature, and we derive analytic approximations to the solutions of the perturbation equations in the two physically interesting limits of all dark matter weakly interacting or a small fraction of dark matter strongly interacting.Keywords
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This publication has 62 references indexed in Scilit:
- Conservative constraints on early cosmology with MONTE PYTHONJournal of Cosmology and Astroparticle Physics, 2013
- The Cosmic Linear Anisotropy Solving System (CLASS). Part II: Approximation schemesJournal of Cosmology and Astroparticle Physics, 2011
- Signatures of relativistic neutrinos in CMB anisotropy and matter clusteringPhysical Review D, 2004
- Cosmological Fluctuations of Small WavelengthThe Astrophysical Journal, 2002
- Constraining dark matter candidates from structure formationPhysics Letters B, 2001
- Weighing Neutrinos with Galaxy SurveysPhysical Review Letters, 1998
- Dynamics of relativistic interacting gases: from a kinetic to a fluid descriptionClassical and Quantum Gravity, 1998
- Small‐Scale Cosmological Perturbations: An Analytic ApproachThe Astrophysical Journal, 1996
- Cosmological Perturbation Theory in the Synchronous and Conformal Newtonian GaugesThe Astrophysical Journal, 1995
- The Analysis of Counts of the Extragalactic Nebulae in Terms of a Fluctuating Density Field. II.The Astrophysical Journal, 1954