TY - JOUR

T1 - The 6dF Galaxy Survey: bulk flows on 50-70 h -1 Mpc scales

AU - Scrimgeour, Morag I.

AU - Davis, Tamara M.

AU - Blake, Chris

AU - Staveley-Smith, Lister

AU - Magoulas, Christina

AU - Springob, Christopher M.

AU - Beutler, Florian

AU - Colless, Matthew

AU - Johnson, Andrew

AU - Jones, D. Heath

AU - Koda, Jun

AU - Lucey, John R.

AU - Ma, Yin-Zhe

AU - Mould, Jeremy

AU - Poole, Gregory B.

PY - 2016/1/1

Y1 - 2016/1/1

N2 - We measure the bulk flow of the local Universe using the 6dF Galaxy Survey peculiar velocity sample (6dFGSv), the largest and most homogeneous peculiar velocity sample to date. 6dFGSv is a Fundamental Plane sample of ∼104 peculiar velocities covering the whole Southern hemisphere for galactic latitude |b| > 10°, out to redshift z = 0.0537. We apply the ‘minimum variance’ bulk flow weighting method, which allows us to make a robust measurement of the bulk flow on scales of 50 and 70 h−1 Mpc. We investigate and correct for potential bias due to the lognormal velocity uncertainties, and verify our method by constructing Λ cold dark matter (ΛCDM) 6dFGSv mock catalogues incorporating the survey selection function. For a hemisphere of radius 50 h−1 Mpc we find a bulk flow amplitude of U = 248 ± 58 km s−1 in the direction (l, b) = (318° ± 20°, 40° ± 13°), and for 70 h−1 Mpc we find U = 243 ± 58 km s−1, in the same direction. Our measurement gives us a constraint on σ8 of 1.01+1.07−0.58. Our results are in agreement with other recent measurements of the direction of the bulk flow, and our measured amplitude is consistent with a ΛCDM prediction.

AB - We measure the bulk flow of the local Universe using the 6dF Galaxy Survey peculiar velocity sample (6dFGSv), the largest and most homogeneous peculiar velocity sample to date. 6dFGSv is a Fundamental Plane sample of ∼104 peculiar velocities covering the whole Southern hemisphere for galactic latitude |b| > 10°, out to redshift z = 0.0537. We apply the ‘minimum variance’ bulk flow weighting method, which allows us to make a robust measurement of the bulk flow on scales of 50 and 70 h−1 Mpc. We investigate and correct for potential bias due to the lognormal velocity uncertainties, and verify our method by constructing Λ cold dark matter (ΛCDM) 6dFGSv mock catalogues incorporating the survey selection function. For a hemisphere of radius 50 h−1 Mpc we find a bulk flow amplitude of U = 248 ± 58 km s−1 in the direction (l, b) = (318° ± 20°, 40° ± 13°), and for 70 h−1 Mpc we find U = 243 ± 58 km s−1, in the same direction. Our measurement gives us a constraint on σ8 of 1.01+1.07−0.58. Our results are in agreement with other recent measurements of the direction of the bulk flow, and our measured amplitude is consistent with a ΛCDM prediction.

U2 - 10.1093/mnras/stv2146

DO - 10.1093/mnras/stv2146

M3 - Article

JO - Monthly Notices of the Royal Astronomical Society

JF - Monthly Notices of the Royal Astronomical Society

SN - 0035-8711

ER -