The variance of the locally measured Hubble parameter explained with different estimators

TY - JOUR

T1 - The variance of the locally measured Hubble parameter explained with different estimators

AU - Odderskov, Io

AU - Hannestad, Steen

AU - Brandbyge, Jacob

PY - 2017/3/13

Y1 - 2017/3/13

N2 - We study the expected variance of measurements of the Hubble constant, H0, as calculated in either linear perturbation theory or using non-linear velocity power spectra derived from N-body simulations. We compare the variance with that obtained by carrying out mock observations in the N-body simulations, and show that the estimator typically used for the local Hubble constant in studies based on perturbation theory is different from the one used in studies based on N-body simulations. The latter gives larger weight to distant sources, which explains why studies based on N-body simulations tend to obtain a smaller variance than that found from studies based on the power spectrum. Although both approaches result in a variance too small to explain the discrepancy between the value of H0 from CMB measurements and the value measured in the local universe, these considerations are important in light of the percent determination of the Hubble constant in the local universe.

AB - We study the expected variance of measurements of the Hubble constant, H0, as calculated in either linear perturbation theory or using non-linear velocity power spectra derived from N-body simulations. We compare the variance with that obtained by carrying out mock observations in the N-body simulations, and show that the estimator typically used for the local Hubble constant in studies based on perturbation theory is different from the one used in studies based on N-body simulations. The latter gives larger weight to distant sources, which explains why studies based on N-body simulations tend to obtain a smaller variance than that found from studies based on the power spectrum. Although both approaches result in a variance too small to explain the discrepancy between the value of H0 from CMB measurements and the value measured in the local universe, these considerations are important in light of the percent determination of the Hubble constant in the local universe.

KW - cosmic ows

KW - cosmological parameters from LSS

KW - cosmological simulations

KW - power spectrum

UR - http://www.scopus.com/inward/record.url?scp=85016939409&partnerID=8YFLogxK

U2 - 10.1088/1475-7516/2017/03/022

DO - 10.1088/1475-7516/2017/03/022

M3 - Journal article

AN - SCOPUS:85016939409

SN - 1475-7516

VL - 2017

JO - Journal of Cosmology and Astroparticle Physics

JF - Journal of Cosmology and Astroparticle Physics

IS - 3

M1 - 022

ER -