Neutrino Properties with Ground-based Millimeter-wavelength Line Intensity Mapping

Azadeh Moradinezhad Dizgah,Garrett K Keating,Shouvik Roy Choudhury,Kirit S Karkare,Abigail Crites

doi:10.3847/1538-4357/ac3edd

Abstract

Abstract Line intensity mapping (LIM) is emerging as a powerful technique to map the cosmic large-scale structure and to probe cosmology over a wide range of redshifts and spatial scales. We perform Fisher forecasts to determine the optimal design of wide-field ground-based millimeter-wavelength LIM surveys for constraining properties of neutrinos and light relics. We consider measuring the auto-power spectra of several CO rotational lines (from J = 2–1 to J = 6–5) and the [C ii] fine-structure line in the redshift range of 0.25 < z < 12. We study the constraints with and without interloper lines as a source of noise in our analysis, and for several one-parameter and multiparameter extensions of ΛCDM. We show that LIM surveys deployable this decade, in combination with existing cosmic microwave background (CMB; primary) data, could achieve order-of-magnitude improvements over Planck constraints on N eff and M ν . Compared to next-generation CMB and galaxy surveys, a LIM experiment of this scale could achieve bounds that are a factor of ∼3 better than those forecasted for surveys such as EUCLID (galaxy clustering), and potentially exceed the constraining power of CMB-S4 by a factor of ∼1.5 and ∼3 for N eff and M ν , respectively. We show that the forecasted constraints are not substantially affected when enlarging the parameter space, and additionally demonstrate that such a survey could also be used to measure ΛCDM parameters and the dark energy equation of state exquisitely well.

Highlights

Neutrinos are among the most abundant particles in the Universe, and affect different epochs in the cosmic history
In this paper we explore constraining neutrino properties using ground-based millimeter-wave Line intensity mapping (LIM) observations, in particular focusing on next-generation instrument configurations that could feasibly be deployed in the decade
The gray horizontal lines are Planckonly constraints, with the lighter lines correspond to LIM-only constraints, while darker lines are obtained from the combination of Planck and LIM

Summary

Introduction

Neutrinos are among the most abundant particles in the Universe, and affect different epochs in the cosmic history. Cosmological observations are sensitive to the effective number of neutrinos, Neff , when they were still relativistic and contributed to the radiation content of the Universe, as well as their total mass, Mν ≡ Σmν, when they became non-relativistic and contribute to the matter content (Abazajian et al 2016; Lattanzi & Gerbino 2018; Lesgourgues et al 2013). Observations of large-scale structure (LSS) will be complementary to CMB, in ameliorating parameter degeneracies (e.g., between Neff and ΛCDM parameters as well as with the sum of neutrino masses and primordial Helium abundance (Baumann et al 2018; Sprenger et al 2019; DePorzio et al 2021)). Since Neff measures the total energy density in radiation excluding photons, a highsignificance detection of an excess light relic abundance, Moradinezhad Dizgah & Keating et al

Methods

Results

Conclusion