Cosmological Constraints on Interacting Light Particles

Abstract

Cosmological observations are becoming increasingly sensitive to the effects of light particles in the form of dark radiation (DR) at the time of recombination. The conventional observable of effective neutrino number, $N_{\mathrm{eff}}$, is insufficient for probing generic, interacting models of DR. In this work, we perform likelihood analyses which allow both free-streaming effective neutrinos (parametrized by $N_{\mathrm{eff}}$) and interacting effective neutrinos (parametrized by $N_{\mathrm{fld}}$). We motivate an alternative parametrization of DR in terms of $N_{\mathrm{tot}}$ (total effective number of neutrinos) and $f_{\mathrm{fs}}$ (the fraction of effective neutrinos which are free-streaming), which is less degenerate than using $N_{\mathrm{eff}}$ and $N_{\mathrm{fld}}$. Using the Planck 2015 likelihoods in conjunction with measurements of baryon acoustic oscillations (BAO), we find constraints on the total amount of beyond the Standard Model effective neutrinos (both free-streaming and interacting) of $\Delta N_{\mathrm{tot}}<0.39$ at 2$\sigma$. In addition, we consider the possibility that this scenario alleviates the tensions between early-time and late-time cosmological observations, in particular the measurements of ${\sigma }_8$ (the amplitude of matter power fluctuations at 8$h^{-1}$ Mpc), finding a mild preference for interactions among light species. We further forecast the sensitivities of a variety of future experiments, including Advanced ACTPol (a representative CMB Stage-III experiment), CMB Stage-IV, and the Euclid satellite. This study is relevant for probing non-standard neutrino physics as well as a wide variety of new particle physics models beyond the Standard Model that involve dark radiation.

14 pages plus appendix and references

References in corpus (8)

• The Clustering of the SDSS DR7 Main Galaxy Sample I: A 4 per cent Distance Measure at z=0.15
• The trouble with $H_0$
• Dark Matter and Dark Radiation
• Relic neutrino decoupling with flavour oscillations revisited
• SPT-3G: A Next-Generation Cosmic Microwave Background Polarization Experiment on the South Pole Telescope
• CFHTLenS: Cosmological constraints from a combination of cosmic shear two-point and three-point correlations
• Dark Radiation Emerging After Big Bang Nucleosynthesis?
• A theory of extra radiation in the Universe

Cited by in corpus (52)

• In the Realm of the Hubble tension $-$ a Review of Solutions
• Dark Matter Self-interactions and Small Scale Structure
• The $H_0$ Olympics: A fair ranking of proposed models
• CMB-S4 Science Case, Reference Design, and Project Plan
• The Neutrino Puzzle: Anomalies, Interactions, and Cosmological Tensions
• Resolving the Hubble Tension with New Early Dark Energy
• Elucidating $\Lambda$CDM: Impact of Baryon Acoustic Oscillation Measurements on the Hubble Constant Discrepancy
• Can the $H_0$ tension be resolved in extensions to $\Lambda$CDM cosmology?
• A CMB Search for the Neutrino Mass Mechanism and its Relation to the $H_0$ Tension
• A Vacuum Phase Transition Solves $H_0$ Tension
• Probing the pre-BBN universe with gravitational waves from cosmic strings
• Gravitational probes of dark matter physics
• Probing Physics Beyond the Standard Model: Limits from BBN and the CMB Independently and Combined
• Constraining Dark Matter -- Dark Radiation interactions with CMB, BAO, and Lyman-$\alpha$
• Primordial Anisotropies in the Gravitational Wave Background from Cosmological Phase Transitions
• Interacting radiation after Planck and its implications for the Hubble Tension
• A Step in Understanding the Hubble Tension
• Thermal Dark Matter Below an MeV
• Gravitational Waves from Global Cosmic Strings and Cosmic Archaeology
• Causal gravitational waves as a probe of free streaming particles and the expansion of the Universe
• $\Lambda$CDM or self-interacting neutrinos? - how CMB data can tell the two models apart
• A Thermal Neutrino Portal to Sub-MeV Dark Matter
• Signatures of Dark Radiation in Neutrino and Dark Matter Detectors
• A Step in Understanding the $S_8$ Tension
• Warm Decaying Dark Matter and the Hubble Tension
• Mirror Twin Higgs Cosmology: Constraints and a Possible Resolution to the $H_0$ and $S_8$ Tensions
• Bayesian Evidence against Harrison-Zel'dovich spectrum in tension cosmology
• Cosmological Implications of Axion-Matter Couplings
• Free-streaming and Coupled Dark Radiation Isocurvature Perturbations: Constraints and Application to the Hubble Tension
• The cosmological impact of future constraints on $H_0$ from gravitational-wave standard sirens
• Stepped Partially Acoustic Dark Matter, Large Scale Structure, and the Hubble Tension
• Confronting interacting dark radiation scenarios with cosmological data
• Wandering in the Lyman-alpha Forest: A Study of Dark Matter-Dark Radiation Interactions
• Profiling Cold New Early Dark Energy
• Strong Bounds on Sum of Neutrino Masses in a 12 Parameter Extended Scenario with Non-Phantom Dynamical Dark Energy ($w(z)\ge -1$)
• Unraveling the Dirac Neutrino with Cosmological and Terrestrial Detectors
• Scaling Transformations and the Origins of Light Relics Constraints from Cosmic Microwave Background Observations
• Global view of neutrino interactions in cosmology: The freestreaming window as seen by Planck
• Probing neutrino interactions and dark radiation with gravitational waves
• The effect of dark matter-dark radiation interactions on halo abundance -- a Press-Schechter approach
• Neutrino Interactions in the Late Universe
• Exploring Mirror Twin Higgs Cosmology with Present and Future Weak Lensing Surveys
• Conversion of Gravitons into Dark Photons in Cosmological Dark Magnetic Fields
• Abundance and properties of dark radiation from the cosmic microwave background
• Free-Streaming Neutrinos and Their Phase Shift in Current and Future CMB Power Spectra
• Directly Probing Neutrino Interactions through CMB Phase Shift Measurements
• Linking the $R_{K^{(\ast )}}$ anomalies to the Hubble tension via a single right-handed neutrino
• Phantom Dirac-Born-Infeld Dark Energy
• Visualizing Invisible Dark Matter Annihilation with the CMB and Matter Power Spectrum
• Dark Matter-Radiation Scattering Enhances CMB Phase Shift through Dark Matter-loading
• Reconciling Cosmological Tensions with Inelastic Dark Matter and Dark Radiation in a $\mathbf{U}(1{)}_{\mathbf{D}}$ Framework
• Cosmological Implications of a Neutrino Mass Detection