Inflationary Freedom and Cosmological Neutrino Constraints

Abstract

The most stringent bounds on the absolute neutrino mass scale come from cosmological data. These bounds are made possible because massive relic neutrinos affect the expansion history of the universe and lead to a suppression of matter clustering on scales smaller than the associated free streaming length. However, the resulting effect on cosmological perturbations is relative to the primordial power spectrum of density perturbations from inflation, so freedom in the primordial power spectrum affects neutrino mass constraints. Using measurements of the cosmic microwave background, the galaxy power spectrum and the Hubble constant, we constrain neutrino mass and number of species for a model independent primordial power spectrum. Describing the primordial power spectrum by a 20-node spline, we find that the neutrino mass upper limit is a factor three weaker than when a power law form is imposed, if only CMB data are used. The primordial power spectrum itself is constrained to better than 10 % in the wave vector range $k\approx 0.01-0.25$ Mpc${}^{-1}$. Galaxy clustering data and a determination of the Hubble constant play a key role in reining in the effects of inflationary freedom on neutrino constraints. The inclusion of both eliminates the inflationary freedom degradation of the neutrino mass bound, giving for the sum of neutrino masses $\Sigma m_{\nu }<0.18$ eV (at 95 % confidence level, Planck+BOSS+$H_0$), approximately independent of the assumed primordial power spectrum model. When allowing for a free effective number of species, $N_{eff}$, the joint constraints on $\Sigma m_{\nu }$ and $N_{eff}$ are loosened by a factor 1.7 when the power law form of the primordial power spectrum is abandoned in favor of the spline parametrization.

17 pages, 8 figures; v2 accepted for publication in Phys Rev D, minor changes relative to v1

References in corpus (6)

• Wilkinson Microwave Anisotropy Probe (WMAP) Three Year Results: Implications for Cosmology
• BBN And The CMB Constrain Light, Electromagnetically Coupled WIMPs
• Reconstruction of the Primordial Power Spectrum using Temperature and Polarisation Data from Multiple Experiments
• WMAP 3-year primordial power spectrum
• Reconstruction of the primordial fluctuation spectrum from the five-year WMAP data by the cosmic inversion method with band-power decorrelation analysis
• CMB Constraints on Principal Components of the Inflaton Potential

Cited by in corpus (26)

• The Simons Observatory: Science goals and forecasts
• CMB-S4 Science Case, Reference Design, and Project Plan
• First Cosmological Results using Type Ia Supernovae from the Dark Energy Survey: Measurement of the Hubble Constant
• Features and New Physical Scales in Primordial Observables: Theory and Observation
• Neutrino Mass Ordering from Oscillations and Beyond: 2018 Status and Future Prospects
• The clustering of galaxies in the SDSS-III Baryon Oscillation Spectroscopic Survey: Signs of neutrino mass in current cosmological datasets
• Relic Neutrinos, thermal axions and cosmology in early 2014
• Primordial power spectrum from Planck
• No new cosmological concordance with massive sterile neutrinos
• Strong Bayesian Evidence for the Normal Neutrino Hierarchy
• The Knotted Sky II: Does BICEP2 require a nontrivial primordial power spectrum?
• The Knotted Sky I: Planck constraints on the primordial power spectrum
• Search for features in the spectrum of primordial perturbations using Planck and other datasets
• Dark Radiation and Inflationary Freedom after Planck 2015
• Cosmology-marginalized approaches in Bayesian model comparison: the neutrino mass as a case study
• Tests of Neutrino and Dark Radiation Models from Galaxy and CMB surveys
• Testing for New Physics: Neutrinos and the Primordial Power Spectrum
• Light Sterile Neutrinos and Inflationary Freedom
• Primordial Power Spectrum features and $f_{NL}$ constraints
• CMB anomalies and the effects of local features of the inflaton potential
• Cosmological bound on neutrino masses in the light of $H_0$ tension
• Inflation and Dark Energy from spectroscopy at $z>2$
• Exploring Early and Late Cosmology with Next Generation Surveys
• Robustness of cosmological axion mass limits
• Dark Radiation and Inflationary Freedom
• Dark Radiation and Inflationary Freedom