Towards a multi-tracer cosmological measurement of neutrino masses.

by Ms. Gali Shmueli

BGU

at Astrophysics and Cosmology Seminar

Wed, 03 Jul 2024, 11:10
Sacta-Rashi Building for Physics (54), room 207

Abstract

Massive neutrinos modify the expansion history of the universe and suppress the structure formation below their free streaming scale. While neutrino oscillation experiments have provided only limited information, the quest to measure the sum of neutrino masses using cosmology has begun. Cosmic microwave background (CMB) observations at small angular scales can be used to constrain the total mass Σmν of the three neutrino flavors. However, at these scales, the CMB measured Σmν is degenerate with τ , the optical depth to reionization. To overcome this challenge, we utilize 21-cm power spectrum observations, enabling direct estimates for τ and breaking the degeneracy. Forecasting for the upcoming Hydrogen Epoch of Reionization Array (HERA) for a joint analysis of CMB and 21-cm data, we find that a ≲ O(10%) measurement of τ is achievable, which would enable a ≳ 5σ measurement of Σmν = 60 [meV]. Further work concerning the late universe explores the effect of massive neutrinos on the growth rate of structure. Here we wish to go beyond the analysis of density fluctuations and explore their impact on velocity fluctuations as well. To further refine our understanding, additional constraints on neutrino masses are derived through the reconstruction of the velocity field, achieved via cross-correlations with large-scale structure tracers, a technique known as velocity tomography. We utilize the kSZ and moving lens effects and forecast for future galaxy and LIM surveys, using Vera Rubin and the CII detector AtLAST as our study cases. We find that velocity tomography improvements are relevant in the case of galaxy surveys, lowering our forecasted uncertainties by 20 percent. On the other hand, LIM by itself has a stronger constraining power, regardless whether we include velocity tomography. We find lowest value of \sigma(\Sigma m_\nu)=70meV using the expected specs of AtLAST, reaching down to ~20meV adding data from CMB-S4, DESI-BAO and velocities.

Created on 30-06-2024 by Zitrin, Adi (zitrin)
Updaded on 30-06-2024 by Zitrin, Adi (zitrin)