A tale of two modes: Neutrino free-streaming in the early universe

Abstract

We present updated constraints on the free-streaming nature of cosmological neutrinos from cosmic microwave background (CMB) power spectra, baryonic acoustic oscillation data, and local measurements of the Hubble constant. Specifically, we consider a Fermi-like four-fermion interaction between massless neutrinos, characterized by an effective coupling constant $G_{\mathrm{eff}}$, and resulting in a neutrino opacity ${\dot{\tau }}_{\nu }\propto G_{\mathrm{eff}}^2{T}_{\nu }^5$. Using a conservative prior on the parameter ${\log }_{10}\left(G_{\mathrm{eff}}{\mathrm{MeV}}^2\right)$, we find a bimodal posterior distribution. The first of these modes is consistent with the standard $\Lambda$CDM cosmology and corresponds to neutrinos decoupling at redshift $z_{\nu ,\mathrm{dec}}>1.3\times 10^5$. The other mode of the posterior, dubbed the "interacting neutrino mode", corresponds to neutrino decoupling occurring within a narrow redshift window centered around $z_{\nu ,\mathrm{dec}}\sim 8300$. This mode is characterized by a high value of the effective neutrino coupling constant, together with a lower value of the scalar spectral index and amplitude of fluctuations, and a higher value of the Hubble parameter. Using both a maximum likelihood analysis and the ratio of the two mode's Bayesian evidence, we find the interacting neutrino mode to be statistically disfavored compared to the standard $\Lambda$CDM cosmology. Interestingly, the addition of CMB polarization and direct Hubble constant measurements significantly raises the statistical significance of this secondary mode, indicating that new physics in the neutrino sector could help explain the difference between local measurements of $H_0$, and those inferred from CMB data. A robust consequence of our results is that neutrinos must be free streaming long before the epoch of matter-radiation equality.

22 pages + references, 9 figures, 4 tables, references added

Cited by in corpus (105)

• In the Realm of the Hubble tension $-$ a Review of Solutions
• Challenges for $\Lambda$CDM: An update
• The Hubble Hunter's Guide
• Cosmology Intertwined II: The Hubble Constant Tension
• The $H_0$ Olympics: A fair ranking of proposed models
• The Neutrino Puzzle: Anomalies, Interactions, and Cosmological Tensions
• The CosmoVerse White Paper: Addressing observational tensions in cosmology with systematics and fundamental physics
• Acoustic Dark Energy: Potential Conversion of the Hubble Tension
• Resolving the Hubble Tension with New Early Dark Energy
• Constraining the Self-Interacting Neutrino Interpretation of the Hubble Tension
• Sterile Neutrinos
• The BAO+BBN take on the Hubble tension
• Interacting Dark Sector and Precision Cosmology
• A CMB Search for the Neutrino Mass Mechanism and its Relation to the $H_0$ Tension
• Early dark energy resolution to the Hubble tension in light of weak lensing surveys and lensing anomalies
• Tensions in the dark: shedding light on Dark Matter-Dark Energy interactions
• Unified framework for Early Dark Energy from $\alpha$-attractors
• A larger value for $H_0$ by an evolving gravitational constant
• Observational Constraints on Secret Neutrino Interactions from Big Bang Nucleosynthesis
• Scalar-tensor theories of gravity, neutrino physics, and the $H_0$ tension
• Updated constraints on massive neutrino self-interactions from cosmology in light of the $H_0$ tension
• Interacting radiation after Planck and its implications for the Hubble Tension
• Thermal Dark Matter Below an MeV
• Inflation meets neutrinos
• Neutrino Self-Interactions: A White Paper
• Cosmological constraints on neutrino self-interactions with a light mediator
• Revisiting Neutrino Self-Interaction Constraints from $Z$ and $\tau$ decays
• Combined analysis of Planck and SPTPol data favors the early dark energy models
• The Hubble tension and a renormalizable model of gauged neutrino self-interactions
• The Hubble Tension as a Hint of Leptogenesis and Neutrino Mass Generation
• $\Lambda$CDM or self-interacting neutrinos? - how CMB data can tell the two models apart
• Flavor-specific Interaction Favors Strong Neutrino Self-coupling in the Early Universe
• Neutrino Self-Interactions and Double Beta Decay
• Probing Secret Interactions of Astrophysical Neutrinos in the High-Statistics Era
• Testing H0 in Acoustic Dark Energy Models with Planck and ACT Polarization
• A Thermal Neutrino Portal to Sub-MeV Dark Matter
• Dark Neutrino interactions phase out the Hubble tension
• Decaying Sterile Neutrinos and the Short Baseline Oscillation Anomalies
• Invisible neutrino decay in precision cosmology
• Self-interacting neutrinos: solution to Hubble tension versus experimental constraints
• Testing Moduli and Flavon Dynamics with Neutrino Oscillations
• Distinguishing Dirac and Majorana neutrinos by their gravi-majoron decays
• Tau Neutrinos in the Next Decade: from GeV to EeV
• Time-varying neutrino mass from a supercooled phase transition: current cosmological constraints and impact on the ${\Omega }_m$-${\sigma }_8$ plane
• Probing non-standard neutrino interactions with a light boson from next galactic and diffuse supernova neutrinos
• Bounds on neutrino-scalar nonstandard interactions from big bang nucleosynthesis
• Towards Powerful Probes of Neutrino Self-Interactions in Supernovae
• Probing secret interactions of eV-scale sterile neutrinos with the diffuse supernova neutrino background
• Cannibal Dark Matter and Large Scale Structure
• Reconstruction of the neutrino mass as a function of redshift
• Massive neutrino self-interactions and inflation
• Probing Decoupling in Dark Sectors with the Cosmic Microwave Background
• Solving the Hubble tension without spoiling Big Bang Nucleosynthesis
• Leptonic Scalars at the LHC
• Self-Interacting Neutrinos in Light of Large-Scale Structure Data
• Updating non-standard neutrinos properties with Planck-CMB data and full-shape analysis of BOSS and eBOSS galaxies
• Cosmology Intertwined: A Review of the Particle Physics, Astrophysics, and Cosmology Associated with the Cosmological Tensions and Anomalies
• The two-mode puzzle: Confronting self-interacting neutrinos with the full shape of the galaxy power spectrum
• Resolving Hubble Tension by Self-Interacting Neutrinos with Dirac Seesaw
• Precision CMB constraints on eV-scale bosons coupled to neutrinos
• Massive neutrino self-interactions with a light mediator in cosmology
• High-energy cosmic neutrinos as a probe of the vector mediator scenario in light of the muon $g-2$ anomaly and Hubble tension
• Probing neutrino interactions and dark radiation with gravitational waves
• Global view of neutrino interactions in cosmology: The freestreaming window as seen by Planck
• Tritium beta decay with additional emission of new light bosons
• Alleviating $H_0$ tension in Horndeski gravity
• Neutrino Oscillations through the Earth's Core
• Strong constraints on a simple self-interacting neutrino cosmology
• The role of CMB spectral distortions in the Hubble tension: a proof of principle
• Flavour specific neutrino self-interaction: $H_0$ tension and IceCube
• Resonant neutrino self-interactions and the $H_0$ tension
• Neutrino masses from large-scale structures: future sensitivity and theory dependence
• Neutrino secret self-interactions: a booster shot for the cosmic neutrino background
• Reducing the $H_0$ Tension with Exponential Acoustic Dark Energy
• X-ray morphology of cluster-mass haloes in self-interacting dark matter
• Enhanced neutrino polarizability
• Constraining dynamical neutrino mass generation with cosmological data
• Modified majoron model for cosmological anomalies
• First constraints on non-minimally coupled Natural and Coleman-Weinberg inflation and massive neutrino self-interactions with Planck+BICEP/Keck
• Fresh Look at Neutrino Self-Interactions With the Lyman-$\alpha$ Forest: Constraints from EFT and PRIYA Simulations
• Free-Streaming Neutrinos and Their Phase Shift in Current and Future CMB Power Spectra
• Abundance and properties of dark radiation from the cosmic microwave background
• Cosmological Distances And Hubble Tension In Einstein-Cartan Theory
• Time-delayed neutrino emission from supernovae as a probe of dark matter-neutrino interactions
• Exploring neutrino interactions in light of present and upcoming galaxy surveys
• Self-interacting neutrinos, the Hubble parameter tension, and the Cosmic Microwave Background
• Gravitational memory signal from neutrino self-interactions in supernova
• Impact of the cosmic neutrino background on black hole superradiance
• Synergy Between Hubble Tension Motivated Self-Interacting Neutrino and KeV-Sterile Neutrino Dark Matter
• Directly Probing Neutrino Interactions through CMB Phase Shift Measurements
• Joint 21-cm and CMB Forecasts for Constraining Self-Interacting Massive Neutrinos
• Early Growth of Structure in Warm Wave Dark Matter
• Non-conservation of Lepton Numbers in the Neutrino Sector Could Change the Prospects for Core Collapse Supernova Explosions
• Resonant neutrino self-interactions: Insights from the full shape galaxy power spectrum
• Probing Long-Range Forces Between Neutrinos with Cosmic Structures
• Do neutrinos bend? Consequences of an ultralight gauge field as dark matter
• Impostor Among $\nu$s: Dark Radiation Masquerading as Self-Interacting Neutrinos
• Dark Matter-Radiation Scattering Enhances CMB Phase Shift through Dark Matter-loading
• Multimodality in the Search for New Physics in Pulsar Timing Data and the Case of Kination-amplified Gravitational-wave Background from Inflation
• $H_0$ Without the Sound Horizon (or Supernovae): A 2% Measurement in DESI DR1
• Simulating neutrino echoes induced by secret neutrino interactions
• Structure Formation with Warm White Noise: Effects of Finite Number Density and Velocity Dispersion in Particle and Wave Dark Matter
• Neutrino condensation from a New Higgs Interaction
• Bias in the tensor-to-scalar ratio from self-interacting dark radiation
• Constraining self-interacting ultrahigh-energy muon neutrinos by cosmic microwave background spectral distortion