A Semiblind Reconstruction of the History of Effective Number of Neutrinos Using CMB Data

Abstract

We explore the possibility of redshift-dependent deviations in the contribution of relativistic degrees of freedom to the radiation budget of the cosmos, conventionally parameterized by the effective number of neutrinos $N_{\mathrm{eff}}$, from the predictions of the standard model. We expand the deviations $\Delta N_{\mathrm{eff}}(z)$ in terms of top-hat functions and treat their amplitudes as the free parameters of the theory to be measured alongside the standard cosmological parameters by the Planck measurements of the cosmic microwave background (CMB) anisotropies and Baryonic Acoustic Oscillations, as well as performing forecasts for futuristic CMB surveys such as PICO and CMB-S4. We reconstruct the history of $\Delta N_{\mathrm{eff}}$ and find that with the current data the history is consistent with the standard scenario. Inclusion of the new degrees of freedom in the analysis increases $H_0$ to $68.71\pm 0.44$, slightly reducing the Hubble tension. With the smaller forecasted errors on the $\Delta N_{\mathrm{eff}}(z)$ parametrization modes from future CMB surveys, very accurate bounds are expected within the possible range of dark radiation models.

arXiv comment7 pages, 7 figures

References in corpus (35)

• Cosmological parameters from CMB and other data: a Monte-Carlo approach
• The 6dF Galaxy Survey: Baryon Acoustic Oscillations and the Local Hubble Constant
• A Comprehensive Measurement of the Local Value of the Hubble Constant with 1 km/s/Mpc Uncertainty from the Hubble Space Telescope and the SH0ES Team
• In the Realm of the Hubble tension $-$ a Review of Solutions
• The Clustering of the SDSS DR7 Main Galaxy Sample I: A 4 per cent Distance Measure at z=0.15
• Planck 2018 results. V. CMB power spectra and likelihoods
• Planck 2018 results. VIII. Gravitational lensing
• Efficient sampling of fast and slow cosmological parameters
• Cosmology Intertwined III: $f{\sigma }_8$ and $S_8$
• Towards a precision calculation of $N_{\mathrm{eff}}$ in the Standard Model II: Neutrino decoupling in the presence of flavour oscillations and finite-temperature QED
• Neutrino decoupling including flavour oscillations and primordial nucleosynthesis
• A precision calculation of relic neutrino decoupling
• Neutrino Physics from the Cosmic Microwave Background and Large Scale Structure
• Cosmological constraints on exotic injection of electromagnetic energy
• Searching for Dark Matter in the CMB: A Compact Parameterization of Energy Injection from New Physics
• Low reheating temperature and the visible sterile neutrino
• A New Target for Cosmic Axion Searches
• Light sterile neutrinos
• The Case for Dark Radiation
• Limits on Dark Radiation, Early Dark Energy, and Relativistic Degrees of Freedom
• Observing Dirac neutrinos in the cosmic microwave background
• Precision Calculation of Dark Radiation from Spinning Primordial Black Holes and Early Matter Dominated Eras
• Additional Light Sterile Neutrinos and Cosmology
• Dirac neutrinos and $N_{\mathrm{eff}}$
• The Cosmophenomenology of Axionic Dark Radiation
• Reconstruction of the neutrino mass as a function of redshift
• The Higgs Boson can delay Reheating after Inflation
• Are Light Sterile Neutrinos Preferred or Disfavored by Cosmology?
• Semi-blind Eigen-analyses of Recombination Histories Using CMB Data
• Constraints on perturbations to the recombination history from measurements of the CMB damping tail
• Two sides of the same coin: sterile neutrinos and dark radiation. Status and perspectives
• Impact of general reionization scenarios on extraction of inflationary parameters
• Was there an early reionization component in our universe?
• Detectable Data-driven Features in the Primordial Scalar Power Spectrum
• Eigen-reconstruction of Perturbations to the Primordial Tensor Power Spectrum

Cited by in corpus (2)

• ${\Lambda }_{\mathrm{s}}$CDM cosmology: Alleviating major cosmological tensions by predicting standard neutrino properties
• Scale and redshift dependent limits on cosmic neutrino properties