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

## Abstract

We study the expected variance of measurements of the Hubble constant, H {sub 0}, 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 H {sub 0} 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.

- Authors:

- Department of Physics and Astronomy, Aarhus University, DK-8000 Aarhus C (Denmark)

- Publication Date:

- OSTI Identifier:
- 22679976

- Resource Type:
- Journal Article

- Resource Relation:
- Journal Name: Journal of Cosmology and Astroparticle Physics; Journal Volume: 2017; Journal Issue: 03; Other Information: Country of input: International Atomic Energy Agency (IAEA)

- Country of Publication:
- United States

- Language:
- English

- Subject:
- 79 ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; COMPARATIVE EVALUATIONS; COMPUTERIZED SIMULATION; DISTURBANCES; NONLINEAR PROBLEMS; PERTURBATION THEORY; RELICT RADIATION; SPECTRA; UNIVERSE; VELOCITY; VISIBLE RADIATION

### Citation Formats

```
Odderskov, Io, Hannestad, Steen, and Brandbyge, Jacob, E-mail: isho07@phys.au.dk, E-mail: sth@phys.au.dk, E-mail: jacobb@phys.au.dk.
```*The variance of the locally measured Hubble parameter explained with different estimators*. United States: N. p., 2017.
Web. doi:10.1088/1475-7516/2017/03/022.

```
Odderskov, Io, Hannestad, Steen, & Brandbyge, Jacob, E-mail: isho07@phys.au.dk, E-mail: sth@phys.au.dk, E-mail: jacobb@phys.au.dk.
```*The variance of the locally measured Hubble parameter explained with different estimators*. United States. doi:10.1088/1475-7516/2017/03/022.

```
Odderskov, Io, Hannestad, Steen, and Brandbyge, Jacob, E-mail: isho07@phys.au.dk, E-mail: sth@phys.au.dk, E-mail: jacobb@phys.au.dk. Wed .
"The variance of the locally measured Hubble parameter explained with different estimators". United States.
doi:10.1088/1475-7516/2017/03/022.
```

```
@article{osti_22679976,
```

title = {The variance of the locally measured Hubble parameter explained with different estimators},

author = {Odderskov, Io and Hannestad, Steen and Brandbyge, Jacob, E-mail: isho07@phys.au.dk, E-mail: sth@phys.au.dk, E-mail: jacobb@phys.au.dk},

abstractNote = {We study the expected variance of measurements of the Hubble constant, H {sub 0}, 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 H {sub 0} 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.},

doi = {10.1088/1475-7516/2017/03/022},

journal = {Journal of Cosmology and Astroparticle Physics},

number = 03,

volume = 2017,

place = {United States},

year = {Wed Mar 01 00:00:00 EST 2017},

month = {Wed Mar 01 00:00:00 EST 2017}

}