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Publication Details
AFRICAN RESEARCH NEXUS
SHINING A SPOTLIGHT ON AFRICAN RESEARCH
earth and planetary sciences
The effect of peculiar velocities on supernova cosmology
Astrophysical Journal, Volume 741, No. 1, Article 67, Year 2011
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Description
We analyze the effect that peculiar velocities have on the cosmological inferences we make using luminosity distance indicators, such as Type Ia supernovae. In particular we study the corrections required to account for (1) our own motion, (2) correlations in galaxy motions, and (3) a possible local under- or overdensity. For all of these effects we present a case study showing the impact on the cosmology derived by the Sloan Digital Sky Survey-II Supernova Survey (SDSS-II SN Survey). Correcting supernova (SN) redshifts for the cosmic microwave background (CMB) dipole slightly overcorrects nearby SNe that share some of our local motion. We show that while neglecting the CMB dipole would cause a shift in the derived equation of state of Δw 0.04 (at fixed Ωm), the additional local-motion correction is currently negligible (Δw ≲ 0.01). We then demonstrate a covariance-matrix approach to statistically account for correlated peculiar velocities. This down-weights nearby SNe and effectively acts as a graduated version of the usual sharp low-redshift cut. Neglecting coherent velocities in the current sample causes a systematic shift of Δw 0.02. This will therefore have to be considered carefully when future surveys aim for percent-level accuracy and we recommend our statistical approach to down-weighting peculiar velocities as a more robust option than a sharp low-redshift cut. © 2011. The American Astronomical Society. All rights reserved.
Authors & Co-Authors
Davis, Tamara M.
Australia, Brisbane
The University of Queensland
Denmark, Copenhagen
Niels Bohr Institutet
Hui, Lam
United States, New York
Columbia University
Frieman, Joshua A.
United States, Chicago
The Kavli Institute for Cosmological Physics
United States, Chicago
The University of Chicago
United States, Batavia
Fermi National Accelerator Laboratory
Haugbølle, Troels
Denmark, Copenhagen
Niels Bohr Institutet
Kessler, Richard S.
United States, Chicago
The Kavli Institute for Cosmological Physics
United States, Chicago
The University of Chicago
Sinclair, Ben
Australia, Brisbane
The University of Queensland
Sollerman, Jesper
Denmark, Copenhagen
Niels Bohr Institutet
Sweden, Stockholm
Stockholms Universitet
Bassett, Bruce A.C.C.
South Africa, Cape Town
University of Cape Town
South Africa, Cape Town
South African Astronomical Observatory
South Africa, Muizenberg
African Institute for Mathematical Sciences
Marriner, John P.
United States, Batavia
Fermi National Accelerator Laboratory
Mörtsell, Edvard
Sweden, Stockholm
Stockholms Universitet
Nichol, Robert C.
United Kingdom, Portsmouth
University of Portsmouth
Richmond, Michael W.
United States, Rochester
Rochester Institute of Technology
Sako, Masao
United States, Philadelphia
University of Pennsylvania
P. Schneider, Donald P.
United States, University Park
Pennsylvania State University
Smith, Matthew W.L.
South Africa, Cape Town
University of Cape Town
Statistics
Citations: 82
Authors: 15
Affiliations: 14
Identifiers
Doi:
10.1088/0004-637X/741/1/67
ISSN:
0004637X
e-ISSN:
15384357
Study Design
Cross Sectional Study
Case Study
Study Approach
Qualitative
Quantitative