Local gravitational redshifts can bias cosmological measurements

Wojtak, Radoslaw, Davis, Tamara M. and Wiis, Jophiel (2015) Local gravitational redshifts can bias cosmological measurements. Journal of Cosmology and Astroparticle Physics, 2015 7: 1-17. doi:10.1088/1475-7516/2015/07/025


Author Wojtak, Radoslaw
Davis, Tamara M.
Wiis, Jophiel
Title Local gravitational redshifts can bias cosmological measurements
Journal name Journal of Cosmology and Astroparticle Physics   Check publisher's open access policy
ISSN 1475-7516
Publication date 2015-07-01
Year available 2015
Sub-type Article (original research)
DOI 10.1088/1475-7516/2015/07/025
Open Access Status Not yet assessed
Volume 2015
Issue 7
Start page 1
End page 17
Total pages 17
Place of publication Bristol, United Kingdom
Publisher Institute of Physics Publishing
Collection year 2016
Language eng
Abstract Measurements of cosmological parameters via the distance-redshift relation usually rely on models that assume a homogenous universe. It is commonly presumed that the large-scale structure evident in our Universe has a negligible impact on the measurement if distances probed in observations are sufficiently large (compared to the scale of inhomogeneities) and are averaged over different directions on the sky. This presumption does not hold when considering the effect of the gravitational redshift caused by our local gravitational potential, which alters light coming from all distances and directions in the same way. Despite its small magnitude, this local gravitational redshift gives rise to noticeable effects in cosmological inference using SN Ia data. Assuming conservative prior knowledge of the local potential given by sampling a range of gravitational potentials at locations of Milky-Way-like galaxies identified in cosmological simulations, we show that ignoring the gravitational redshift effect in a standard data analysis leads to an additional systematic error of ~1% in the determination of density parameters and the dark energy equation of state. We conclude that our local gravitational field affects our cosmological inference at a level that is important in future observations aiming to achieve percent-level accuracy.
Keyword Cosmological simulations
Dark energy experiments
Supernova type Ia - standard candles
Q-Index Code C1
Q-Index Status Confirmed Code
Institutional Status UQ

Document type: Journal Article
Sub-type: Article (original research)
Collections: School of Mathematics and Physics
Official 2016 Collection
 
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